Upload
natalia-gomez
View
37
Download
3
Embed Size (px)
DESCRIPTION
Source: Crime Scene Investigation page
Citation preview
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 1/143
SearchthisSite
Seleccionaridioma
Home CrimeSceneResponse EvidenceCollection SceneandEvidencePhotography Articles Videos
CollegesandTraining BecomeaCSI Employment Forum ResourcesandLinks Bookstore Contact
FreeNewsletter
Newsletter(Monthly)
JobPostings(Daily)
Submit
Signupnowtoreceiveourfreemonthlynewsletterfeaturingarticles,newsandnewjobsavailableinCrimeSceneInvestigationsandForensicScience.
PrivacyStatementMoreaboutthenewsletter
HowtoBecomeaCSI
LearnhowtobecomeaCrimeSceneInvestigator
orForensicScientist
TheScienceofFingerprints
THE
SCIENCEOF
FINGERPRINTS
ClassificationandUses
UNITEDSTATESDEPARTMENTOFJUSTICE
FEDERALBUREAUOFINVESTIGATION
JohnEdgarHoover,Director
INTRODUCTIONThisbookletconcerningthestudyoffingerprintshasbeenpreparedbytheFederalBureauofInvestigationfortheuseofinterestedlawenforcementofficersandagencies,particularlythosewhichmaybecontemplatingtheinaugurationoffingerprintidentificationfiles.Itisbasedonmanyyears'experienceinfingerprintidentificationworkoutofwhichhasdevelopedthelargestcollectionofclassifiedfingerprintsintheworld.Inasmuchasthispublicationmayserveasageneralreferenceonclassificationandotherphasesoffingerprintidentificationwork,thesystemsutilizedintheIdentificationDivisionoftheFederalBureauofInvestigationaresetforthfully.Theproblemofpatterninterpretation,inparticular,isdiscussedindetail.
Criminalidentificationbymeansoffingerprintsisoneofthemostpotentfactorsinobtainingtheapprehensionoffugitiveswhomightotherwiseescapearrestandcontinuetheircriminalactivitiesindefinitely.Thistypeofidentificationalsomakespossibleanaccuratedeterminationofthenumberof
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 2/143
FeaturedProducts
previousarrestsandconvictionswhich,ofcourse,resultsintheimpositionofmoreequitablesentencesbythejudiciary,inasmuchastheindividualwhorepeatedlyviolatesthelawfindsitimpossibletoposesuccessfullyasafirst,orminor,offender.Inaddition,thissystemofidentificationenablestheprosecutortopresenthiscaseinthelightoftheoffender'spreviousrecord.Italsoprovidestheprobationofficers,paroleboard,andtheGovernorwithdefiniteinformationuponwhichtobasetheirjudgmentindealingwithcriminalsintheirjurisdictions.
Fromearliesttimesfingerprinting,becauseofitspeculiaradaptabilitytothefield,hasbeenassociatedinthelaymindwithcriminalidentificationtothedetrimentoftheotherusefulphasesofthescience.However,theCivilFileoftheIdentificationDivisionoftheFederalBureauofInvestigationcontainsthreetimesasmanyfingerprintsastheCriminalFile.Thesecivilfingerprintsareaninvaluableaidinidentifyingamnesiavictims,missingpersonsandunknowndeceased.Inthelattercategorythevictimsofmajordisastersmaybequicklyandpositivelyidentifiediftheirfingerprintsareonfile,thusprovidingahumanitarianbenefitnotusuallyassociatedwithfingerprintrecords.
TheregularcontributorswhovoluntarilysubmitfingerprintstotheFederalBureauofInvestigationplayamostimportantroleinthe[Pgiv]dramaofidentification.Theiractionexpandsthesizeofthefingerprintfiles,therebyincreasingthevalueofthefilestoalllawenforcementagencies.Mutualcooperationandefficiencyareresultantbyproducts.
Theuseoffingerprintsforidentificationpurposesisbasedupondistinctiveridgeoutlineswhichappearonthebulbsontheinsideoftheendjointsofthefingersandthumbs.Theseridgeshavedefinitecontoursandappearinseveralgeneralpatterntypes,eachwithgeneralandspecificvariationsofthepattern,dependentontheshapeandrelationshipoftheridges.Theoutlinesoftheridgesappearmostclearlywheninkedimpressionsaretakenuponpaper,sothattheridgesareblackagainstawhitebackground.Thisresultisachievedbytheinkadheringtothefrictionridges.Impressionsmaybemadewithblood,dirt,greaseoranyotherforeignmatterpresentontheridges,orthesalinesubstanceemittedbytheglandsthroughtheductsorporeswhichconstitutetheiroutlets.Thebackgroundormediummaybepaper,glass,porcelain,wood,cloth,wax,putty,silverware,oranysmooth,nonporousmaterial.
Ofallthemethodsofidentification,fingerprintingalonehasprovedtobebothinfallibleandfeasible.Itssuperiorityovertheoldermethods,suchasbranding,tattooing,distinctiveclothing,photography,andbodymeasurements(Bertillonsystem),hasbeendemonstratedtimeaftertime.Whilemanycasesofmistakenidentificationhaveoccurredthroughtheuseoftheseoldersystems,todatethefingerprintsofnotwoindividualshavebeenfoundtobeidentical.
Thebackgroundandhistoryofthescienceoffingerprintsconstituteaneloquentdramaofhumanlives,ofgoodandofevil.Nothing,Ithink,hasplayedapartmoreexcitingthanthatenactedbythefascinatingloops,whorls,andarchesetchedonthefingersofahumanbeing.
J.EDGARHOOVER,Director.
[Pgv]
CONTENTS
Chapter PageIntroduction iiiI.TheIdentificationDivisionoftheFBI 1II.TypesofPatternsandTheirInterpretation 5III.QuestionablePatterns 71IV.TheClassificationFormulaandExtensions 87V.ClassificationofScarredPatternsAmputationMissingatBirth 98VI.FilingSequence 103VII.SearchingandReferencing 109VIII.HowToTakeInkedFingerprints 114IX.ProblemsintheTakingofInkedFingerprints 118X.ProblemsandPracticesinFingerprintingtheDead 131XI.EstablishmentofaLocalFingerprintIdentificationBureau 160XII.LatentImpressions 173XIII.PowderingandLiftingLatentImpressions 175XIV.ChemicalDevelopmentofLatentImpressions 177XV.TheUseoftheFingerprintCamera 184XVI.PreparationofFingerprintChartsforCourtTestimony 190
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 3/143
LatentFingerprintKit$29.95
XVII.UnidentifiedLatentFingerprintFile 194
CHAPTERI
TheIdentificationDivisionoftheFBI
TheFBIIdentificationDivisionwasestablishedin1924whentherecordsoftheNationalBureauofCriminalInvestigationandtheLeavenworthPenitentiaryBureauwereconsolidatedinWashington,D.C.Theoriginalcollectionofonly810,000fingerprintcardshasexpandedintomanymillions.TheestablishmentoftheFBIIdentificationDivisionresultedfromthefactthatpoliceofficialsoftheNationsawtheneedforacentralizedpoolingofallfingerprintcardsandallarrestrecords.
TheFederalBureauofInvestigationoffersidentificationservicefreeofchargeforofficialusetoalllawenforcementagenciesinthiscountryandtoforeignlawenforcementagencieswhichcooperateintheInternationalExchangeofIdentificationData.Throughthiscentralizationofrecordsitisnowpossibleforanofficertohaveavailableapositivesourceofinformationrelativetothepastactivitiesofanindividualinhiscustody.ItistheBureau'spresentpolicytogivepreferredattentiontoallarrestfingerprintcardssinceitisrealizedthatspeedisessentialinthisservice.
InorderthattheFBIIdentificationDivisioncanprovidemaximumservicetoalllawenforcementagencies,itisessentialthatstandardfingerprintcardsandotherformsfurnishedbytheFBIbeutilized.Fingerprintsmustbeclearanddistinctandcompletenameanddescriptivedatarequiredontheformshouldbefurnishedinallinstances.Fingerprintsshouldbesubmittedpromptlysincedelaymightresultinreleaseofafugitivepriortonotificationtothelawenforcementagencyseekinghisapprehension.
WhenitisknowntoalawenforcementagencythatasubjectunderarrestisanemployeeoftheU.S.GovernmentoramemberoftheArmedForces,anotationshouldbeplacedinthespacefor"occupation"onthefrontofthefingerprintcard.Datasuchaslocationofagencyormilitarypostofassignmentmaybeaddedbesidethespacereservedforthephotographonthereversesideofthecard.
Manyinstanceshavebeenobservedwhereanindividualisfingerprintedbymorethanonelawenforcementagencyforthesamearrest.ThisduplicatesubmissionoffingerprintscanbeeliminatedbyplacinganotationonthefirstsetoffingerprintssenttotheFBIrequestingcopiesoftherecordforotherinterestedlawenforcementagencies,therebyeliminatingsubmissionoffingerprintsbythelatteragencies.
IfaphotographisavailableatthetimefingerprintsaresubmittedtotheFBIIdentificationDivision,itshouldbeidentifiedonthereversesidewiththeindividual'scompletename,nameofthedepartmentsubmitting,thedepartment'snumber,anditshouldbesecurelypastedinthespaceprovidedonthefingerprintcard.Ifaphotographistobesubmittedatalaterdate,itshouldbehelduntiltheidentificationrecordor"norecord"replyfromtheFBIisreceivedinorderthatFBInumberorfingerprintclassificationcanbeaddedtothereversesideofthephotographforassistanceoftheIdentificationDivisioninrelatingittotheproperrecord.
TheFBInumber,ifknown,andanyrequestforspecialhandling,suchascollectwireortelephonereply,shouldbeindicatedonthefingerprintcardintheappropriatespace.Suchnotationseliminatetheneedforanaccompanyingletterofinstructions.
Asindicated,theFBI'sserviceisgivenwithoutcosttoregularlyconstitutedlawenforcementagenciesandofficers.Suppliesoffingerprintcardsandselfaddressed,frankedenvelopeswillbeforwardedupontherequestofanylawenforcementofficer.Thefollowingtypesofcardsandformsareavailable:Criminal(FormFD249),usedforbotharrestandinstitutionrecordsApplicant(FormFD258)PersonalIdentification(FormFD353)DeathSheet(FormR88)DispositionSheet(FormR84)WantedNotice(Form112)RecordofAdditionalArrest(Form11).AnorderformforidentificationsuppliesappearseachmonthwiththeinserttotheFBILawEnforcementBulletin.
Inadditiontoitscriminalidentificationactivities,theBureau'sIdentificationDivisionmaintainsseveralauxiliaryservices.Nottheleastoftheseisthesystemwherebyfugitivesareidentifiedthroughthecomparisonoffingerprintswhicharereceivedcurrently.Whenalawenforcementofficerdesirestheapprehensionofafugitiveandthefingerprintsofthatindividualareavailable,itisnecessaryonlythatheinformtheBureauofthisfactsoawantednoticemaybeplacedinthefugitive'srecord.Thisinsuresimmediatenotificationwhenthefugitive'sfingerprintsarenextreceived.
ThefugitiveserviceisamplifiedbytheBureau'sactionintransmittingamonthlybulletintoalllawenforcementagencieswhichforwardfingerprintsforitsfiles.Inthisbulletinarelistedthenames,descriptions,andfingerprintclassificationsofpersonswantedforoffensesofamoreseriouscharacter.Thisinformationfacilitatespromptidentificationsofindividualsarrestedforanyoffenseorotherwiselocatedbythosereceivingthebulletin.
MissingpersonsnoticesarepostedintheIdentificationfilessothatanyincomingrecordonthemissingpersonwillbenoted.Noticesarepostedbothbyfingerprintcardandbyname,orbynamealoneiffingerprintsarenotavailable.Thefullname,date,andplaceofbirth,completedescriptionandphotographofamissingpersonshouldbeforwarded,alongwithfingerprints,ifavailable.Uponreceiptofpertinentinformation,thecontributingagencyisadvisedimmediately.AsectiononmissingpersonsiscarriedasaninsertintheLawEnforcementBulletin.
TheFBIIdentificationDivisionhasarrangedwiththeidentificationbureausofmanyforeigncountriesto
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 4/143
exchangecriminalidentifyingdataincasesofmutualinterest.FingerprintsandarrestrecordsofpersonsarrestedinthiscountryareroutedtotheappropriateforeignbureausincaseswhentheinterestedagencyintheUnitedStateshasreasontobelieveanindividualincustodymayhavearecordinorbewantedbytheothernation.Similarly,fingerprintsarereferredtotheFederalBureauofInvestigationbyforeignbureauswhenitseemsarecordmaybedisclosedbyasearchoftheBureau'srecords.Numerousidentifications,includinganumberoffugitives,havebeeneffectedinthismanner,anditisbelievedthatthecompletedevelopmentofthisprojectwillprovidemoreeffectivelawenforcementthroughouttheworld.Whenthefactsindicateanindividualmayhavearecordinanothercountry,andthecontributorsubmitsanextrasetofhisfingerprints,theyaretransmittedbythisBureautotheproperauthorities.
Inveryrarecasespersonswithouthandsarearrested.AfileonfootprintsismaintainedintheIdentificationDivisiononsuchindividuals.
Inviewofthefactthatmanyindividualsintheunderworldareknownonlybytheirnicknames,theIdentificationDivisionhasforyearsmaintainedacardindexfilecontaininginalphabeticalorderthenicknamesappearingonfingerprintcards.Whenrequestingasearchofthenicknamefile,itisdesiredthatallpossibledescriptivedatabefurnished.
TheLatentFingerprintSectionhandleslatentprintwork.ArticlesofevidencesubmittedbylawenforcementagenciesareprocessedforthedevelopmentoflatentimpressionsintheLatentFingerprintSection.Inaddition,photographs,negatives,andliftsoflatentsarescrutinizedforprintsofvalueforidentificationpurposes.PhotographsoftheprintsofvaluearealwayspreparedfortheFBI'sfilesandareavailableforcomparisonsforanindefiniteperiod.ShouldthelawenforcementagencydesireadditionalcomparisonsitneedsonlyadvisetheFBIIdentificationDivision,attentionLatentFingerprintSection,andeithernameorsubmittheprintsofthenewsuspect.Itisnotnecessarytoresubmittheevidence.Whennecessary,afingerprintexpertwilltestifyinlocalcourtastohisfindings.Shouldadepartmenthaveanyspecialproblemsinvolvingthedevelopmentorpreservationoffingerprintsatacrimescene,theexpertsareavailableforsuggestions.InconnectionwiththeLatentFingerprintSectionthereismaintainedageneralappearancefileofmanyconfidencegameoperators.Searchesinthisfilewillbemadeuponrequest.Infurnishingdataonasuspect,theagencyshouldmakesurethatcompletedescriptivedataissentin.Photographsandothermaterialonindividualswhomaybeidenticalwiththosebeingsoughtwillbefurnishedtotheinteresteddepartments.
DuringtheyearsmanypersonshavevoluntarilysubmittedtheirfingerprintstotheIdentificationDivisionforpossibleuseinthecaseofanemergency.Thesecardsarenotfiledwiththecriminalfingerprintsbutaremaintainedseparately.Suchprintsshouldbetakenonthestandard[Pg4]fingerprintformentitled"PersonalIdentification"(FormFD353).NoanswerisgiventoPersonalIdentificationfingerprintcards.
ThefingerprintrecordsoftheFBIIdentificationDivisionareusedliberallynotonlybypoliceagenciestoobtainpreviousfingerprinthistoriesandtoascertainwhetherpersonsarrestedarewantedelsewhere,butbyprosecutorstowhomtheinformationfromtheBureau'sfilesmayprovetobevaluableinconnectionwiththeprosecutionofacase.Theserecordsarelikewiseoffrequentvaluetothejudgeforhisconsiderationinconnectionwiththeimpositionofsentence.Obviously,theendsofjusticemaybeservedmostequitablywhenthepastfingerprintrecordofthepersonontrialcanbemadeknowntothecourt,orinformationmaybefurnishedtotheeffectthatthedefendantisofhithertounblemishedreputation.
ItshouldbeemphasizedthatFBIidentificationrecordsarefortheOFFICIALuseoflawenforcementandgovernmentalagenciesandmisuseofsuchrecordsbydisseminatingthemtounauthorizedpersonsmayresultincancellationofFBIidentificationservices.
CHAPTERII
TypesofPatternsandTheirInterpretation
Typesofpatterns
Fingerprintsmayberesolvedintothreelargegeneralgroupsofpatterns,eachgroupbearingthesamegeneralcharacteristicsorfamilyresemblance.Thepatternsmaybefurtherdividedintosubgroupsbymeansofthesmallerdifferencesexistingbetweenthepatternsinthesamegeneralgroup.Thesedivisionsareasfollows:
I.ARCH II.LOOP III.WHORL
a.Plainarch. a.Radialloop. a.Plainwhorl.
b.Tentedarch. b.Ulnarloop. b.Centralpocketloop.
c.Doubleloop.
d.Accidentalwhorl.
Illustrations1to10areexamplesofthevarioustypesoffingerprintpatterns.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 5/143
[Figs.110]
Interpretation
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 6/143
Beforepatterndefinitioncanbeunderstood,itisnecessarytounderstandthemeaningofafewtechnicaltermsusedinfingerprintwork.
Thepatternareaistheonlypartofthefingerimpressionwithwhichweareconcernedinregardtointerpretationandclassification.Itispresentinallpatterns,ofcourse,butinmanyarchesandtentedarchesitisimpossibletodefine.Thisisnotimportant,however,astheonlypatternsinwhichweneedtodefinethepatternareaforclassificationpurposesareloopsandwhorls.Inthesetwopatterntypesthepatternareamaybedefinedasfollows:
Thepatternareaisthatpartofalooporwhorlinwhichappearthecores,deltas,andridgeswithwhichweareconcernedinclassifying.
Thepatternareasofloopsandwhorlsareenclosedbytypelines.
Typelinesmaybedefinedasthetwoinnermostridgeswhichstartparallel,diverge,andsurroundortendtosurroundthepatternarea.
Figure11isatypicalloop.LinesAandB,whichhavebeenemphasizedinthissketch,arethetypelines,startingparallel,divergingatthelineCandsurroundingthepatternarea,whichisemphasizedinfigure12byeliminatingalltheridgeswithinthepatternarea.
[Figs.1112]
Figures72through101shouldbestudiedforthelocationoftypelines./p>
Typelinesarenotalwaystwocontinuousridges.Infact,theyaremoreoftenfoundtobebroken.Whenthereisadefinitebreakinatypeline,theridgeimmediatelyoutsideofitisconsideredasitscontinuation,asshownbytheemphasizedridgesinfigure13.
[Fig.13]
Sometimestypelinesmaybeveryshort.Caremustbeexercisedintheirlocation.Noticetherighttypelineinfigure14.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 7/143
[Fig.14]
Whenlocatingtypelinesitisnecessarytokeepinmindthedistinctionbetweenadivergenceandabifurcation(fig.15).
[Fig.15]
Abifurcationistheforkingordividingofonelineintotwoormorebranches.
Adivergenceisthespreadingapartoftwolineswhichhavebeenrunningparallelornearlyparallel.
Accordingtothenarrowmeaningofthewordsinfingerprintparlance,asingleridgemaybifurcate,butitmaynotbesaidtodiverge.Therefore,withoneexception,thetwoforksofabifurcationmayneverconstitutetypelines.Theexceptioniswhentheforksrunparallelafterbifurcatingandthendiverge.Insuchacasethetwoforksbecomethetwoinnermostridgesrequiredbythedefinition.Inillustration16,theridgesmarked"AA"aretypelineseventhoughtheyproceedfromabifurcation.Infigure17,however,theridgesAAarenotthetypelinesbecausetheforksofthebifurcationdonotrunparallelwitheachother.Instead,theridgesmarked"T"arethetypelines.
[Fig.16]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 8/143
[Fig.17]
Anglesareneverformedbyasingleridgebutbytheabuttingofoneridgeagainstanother.Therefore,anangularformationcannotbeusedasatypeline.Infigure18,ridgesAandBjoinatanangle.RidgeBdoesnotrunparallelwithridgeDridgeAdoesnotdiverge.RidgesCandD,therefore,arethetypelines.
[Fig.18]
FocalpointsWithinthepatternareasofloopsandwhorlsareenclosedthefocalpointswhichareusedtoclassifythem.Thesepointsarecalleddeltaandcore.
Thedeltaisthatpointonaridgeatorinfrontofandnearestthecenterofthedivergenceofthetypelines.
Itmaybe:
Abifurcation
Anabruptendingridge
Adot
Ashortridge
Ameetingoftworidges
Apointonthefirstrecurvingridgelocatednearesttothecenterandinfrontofthedivergenceofthetypelines.
Theconceptofthedeltamayperhapsbeclarifiedbyfurtherexposition.Websterfurnishesthefollowingdefinition:"(1)DeltaisthenameofthefourthletteroftheGreekalphabet(equivalenttotheEnglishD)fromthePhoeniciannameforthecorrespondingletter.TheGreekscalledthealluvialdepositatthemouthoftheNile,fromitsshape,theDeltaoftheNile.(2)Atractoflandshapedliketheletter"delta,"especiallywhenthelandisalluvial,andenclosedwithintwoormoremouthsofariver,astheDeltaoftheGanges,oftheNile,oftheMississippi"(fig.19).
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 9/143
[Fig.19]
Whentheuseoftheword"delta"inphysicalgeographyisfullygrasped,itsfitnessasappliedinfingerprintworkwillbecomeevident.Riverswearawaytheirbanksandcarrythemalongintheirwatersintheformofafinesediment.Astheriversunitewithseasorlakes,theonwardsweepofthewaterislessened,andthesediment,becomingcomparativelystill,sinkstothebottomwherethereisformedashoalwhichgraduallygrows,asmoreandmoreisprecipitated,untilatlengthaportionoftheshoalbecomeshigherthantheordinarylevelofthestream.Thereisasimilaritybetweentheuseoftheword"delta"inphysicalgeographyandinfingerprints.Theislandformedinfrontofthedivergingsidesofthebankswherethestreamemptiesatitsmouthcorrespondstothedeltainfingerprints,whichisthefirstobstructionofanynatureatthepointofdivergenceofthetypelinesinfrontofornearestthecenterofthedivergence.
Infigure20,thedotmarked"delta"isconsideredasthedeltabecauseitisthefirstridgeorpartofaridgenearestthepointofdivergenceofthetwotypelines.Ifthedotwerenotpresent,pointBonridgeC,asshowninthefigure,wouldbeconsideredasthedelta.Thiswouldbeequallytruewhethertheridgeswereconnectedwithoneofthetypelines,bothtypelines,ordisconnectedaltogether.Infigure20,withthedotasthedelta,thefirstridgecountisridgeC.Ifthedotwerenotpresent,pointBonridgeCwouldbeconsideredasthedeltaandthefirstcountwouldberidgeD.ThelinesXXandYYarethetypelines,notXAandYZ.
[Fig.20]
Infigures21to24,theheavylinesAAandBBaretypelineswiththedeltaatpointD.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 10/143
[Figs.2124]
Figure25showsridgeAbifurcatingfromthelowertypelineinsidethepatternarea.BifurcationsarealsopresentwithinthispatternatpointsBandC.Thebifurcationatthepointmarked"delta"istheonlyonewhichfulfillsallconditionsnecessaryforitslocation.Itshouldbeunderstoodthatthedivergingtypelinesmustbepresentinalldeltaformationsandthatwhereveroneoftheformationsmentionedinthedefinitionofadeltamaybe,itmustbelocatedmidwaybetweentwodivergingtypelinesatorjustinfrontofwheretheydivergeinordertosatisfythedefinitionandqualifyasadelta.
[Fig.25]
Whenthereisachoicebetweentwoormorepossibledeltas,thefollowingrulesgovern:
Thedeltamaynotbelocatedatabifurcationwhichdoesnotopentowardthecore.
Infigure26,thebifurcationatEisclosertothecorethanthebifurcationatD.However,Eisnotimmediatelyinfrontofthedivergenceofthetypelinesanditdoesnotopentowardthecore.AAandBBaretheonlypossibletypelinesinthissketchanditfollows,therefore,thatthebifurcationatDmustbecalledthedelta.ThefirstridgecountwouldberidgeC.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 11/143
[Fig.26]
Whenthereisachoicebetweenabifurcationandanothertypeofdelta,thebifurcationisselected.
Aproblemofthistypeisshowninfigure27.Thedot,A,andthebifurcationareequallyclosetothedivergenceofthetypelines,butthebifurcationisselectedasthedelta.Theridgesmarked"T"arethetypelines.
[Fig.27]
Whentherearetwoormorepossibledeltaswhichconformtothedefinition,theonenearestthecoreischosen.
Printsaresometimesfoundwhereinasingleridgeentersthepatternareawithtwoormorebifurcationsopeningtowardthecore.Figure28isanexampleofthis.RidgeAentersthepatternareaandbifurcatesatpointsXandD.ThebifurcationatD,whichistheclosertothecore,is[Pg13]thedeltaandconformstotherulefordeltas.AAandBBarethetypelines.Abifurcationwhichdoesnotconformtothedefinitionshouldnotbeconsideredasadeltairrespectiveofitsdistancefromthecore.
[Fig.28]
Thedeltamaynotbelocatedinthemiddleofaridgerunningbetweenthetypelinestowardthecore,butatthenearerendonly.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 12/143
Thelocationofthedeltainthiscasedependsentirelyuponthepointoforiginoftheridgerunningbetweenthetypelinestowardthecore.Iftheridgeisentirelywithinthepatternarea,thedeltaislocatedattheendnearerthepointofdivergenceofthetypelines.Figure29isanexampleofthiskind.
[Fig.29]
Iftheridgeentersthepatternareafromapointbelowthedivergenceofthetypelines,however,thedeltamustbelocatedattheendnearerthecore.RidgeAinfigure30isofthistype.
[Fig.30]
Infigure31,AAandBBarethetypelines,withthedotasthedelta.Thebifurcationscannotbeconsideredastheydonotopentowardthecore.
[Fig.31]
Infigure32,thedotcannotbethedeltabecauselineDcannotbeconsideredasatypeline.ItdoesnotrunparalleltotypelineAAatanypoint.ThesamereasonpreventslineEfrombeingatypeline.TheendofridgeEistheonlypossibledeltaasitisapointontheridgenearesttothecenterofdivergenceofthetypelines.Theothertypelineis,ofcourse,BB.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 13/143
[Fig.32]
Thedeltaisthepointfromwhichtostartinridgecounting.Inthelooptypepatterntheridgesinterveningbetweenthedeltaandthecorearecounted.Thecoreisthesecondofthetwofocalpoints.
Thecore,asthenameimplies,istheapproximatecenterofthefingerimpression.Itwillbenecessarytoconcernourselveswiththecoreofthelooptypeonly.Thefollowingrulesgoverntheselectionofthecoreofaloop:
Thecoreisplaceduponorwithintheinnermostsufficientrecurve.
Whentheinnermostsufficientrecurvecontainsnoendingridgeorrodrisingashighastheshouldersoftheloop,thecoreisplacedontheshoulderoftheloopfartherfromthedelta.
Whentheinnermostsufficientrecurvecontainsanunevennumberofrodsrisingashighastheshoulders,thecoreisplacedupontheendofthecenterrodwhetherittouchestheloopingridgeornot.
Whentheinnermostsufficientrecurvecontainsanevennumberofrodsrisingashighastheshoulders,thecoreisplacedupontheendofthefartheroneofthetwocenterrods,thetwocenterrodsbeingtreatedasthoughtheywereconnectedbyarecurvingridge.
Theshouldersofalooparethepointsatwhichtherecurvingridgedefinitelyturnsinwardorcurves.
Figures33to38reflectthefocalpointsofaseriesofloops.Infigure39,therearetworods,buttherodmarked"A"doesnotriseashighastheshoulderlineX,sothecoreisatB.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 14/143
[Figs.3339]
Figures40to45illustratetherulethatarecurvemusthavenoappendageabuttinguponitatarightanglebetweentheshouldersandontheoutside.Ifsuchanappendageispresentbetweentheshouldersofaloop,thatloopisconsideredspoiledandthenextloopoutsidewillbeconsideredtolocatethecore.Ineachofthefigures,thepointCindicatesthecore.Appendageswillbefurtherexplainedinthesectionconcerningloops.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 15/143
[Figs.4045]
Figures46to48reflectinterlockingloopsatthecenter,whilefigure49hastwoloopssidebysideatthecenter.Inallthesecasesthetwoloopsareconsideredasone.Infigure46,whentheshoulderlineXXisdrawnitisfoundtocrossexactlyatthepointofintersectionofthetwoloops.Thetwoloopsareconsideredone,withonerod,thecorebeingplacedatC.Infigure47,theshoulderlineXXisabovethepointofintersectionofthetwoloops.Thetwoareconsideredasone,withtworods,thecorebeingatC.Infigure48,theshoulderlineXXisbelowthepointofintersectionoftheloops.Againthetwoaretreatedasone,withtworods,thecorebeingplacedatC.Infigure49,thetwoaretreatedasone,withtworods,thecorebeingplacedatC.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 16/143
[Figs.4649]
Infigure50,thedeltaisformedbyabifurcationwhichisnotconnectedwitheitherofthetypelines.ThefirstridgecountinthisinstanceisridgeC.Ifthebifurcationwerenotpresent,thedeltawouldbeapointonridgeCandthefirstridgecountwouldberidgeD.Infigure51,theridgewhichbifurcatesisconnectedwiththelowertypeline.ThedeltainthiswouldbelocatedonthebifurcationasdesignatedandthefirstridgecountwouldberidgeC.Figure52reflectsthesametypeofdeltashowninthepreviousfigureinthattheridgeisbifurcatingfromatypelineandthenbifurcatesagaintoformthedelta.
[Figs.5052]
Awhitespacemustintervenebetweenthedeltaandthefirstridgecount.Ifnosuchintervalexists,thefirstridgemustbedisregarded.Infigures53and54,thefirstridgebeyondthedeltaiscounted.Infigure55,itisnotcountedbecausethereisnointervalbetweenitandthedelta.Noticethattheridgerunningfromthedeltatowardthecoreisinastraightlinebetweenthem.Ifitwerenot,ofcourse,anintervalwouldinterveneasinfigures53and54.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 17/143
[Figs.5355]
Theloop
Infingerprints,aswellasintheusualapplicationoftheword"loop,"therecannotbealoopunlessthereisarecurveorturningbackonitselfofoneormoreoftheridges.Otherconditionshavetobeconsidered,however.Apatternmustpossessseveralrequisitesbeforeitmaybeproperlyclassifiedasaloop.Thistypeofpatternisthemostnumerousofallandconstitutesabout65percentofallprints.[Pg19]
Aloopisthattypeoffingerprintpatterninwhichoneormoreoftheridgesenteroneithersideoftheimpression,recurve,touchorpassanimaginarylinedrawnfromthedeltatothecore,andterminateortendtoterminateonortowardthesamesideoftheimpressionfromwhencesuchridgeorridgesentered.
Essentialsofaloop
Asufficientrecurve.
Adelta.
Aridgecountacrossaloopingridge.
Asufficientrecurvemaybedefinedasthatpartofarecurvingridgebetweentheshouldersofaloop.Itmustbefreeofanyappendagesabuttingupontheoutsideoftherecurveatarightangle.
AppendagesSomeexplanationisnecessaryoftheimportanceattachedtoappendages.Muchcaremustbeexercisedininterpretingappendagesbecausetheysometimeschangetheshapeoftherecurvingridgetowhichtheyareconnected.Forexample,aloopwithanappendageabuttinguponitsrecurvebetweentheshouldersandatrightangles,asinillustration56,willappearsometimesasinillustration57withtherecurvetotallydestroyed.Forfurtherexamplesseefigures161to184.
[Figs.5657]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 18/143
Thesameistrueofawhorlrecurve,asinfigures58and59.
[Figs.5859]
Itisnecessary,therefore,toconsiderandclassifyfigures56and58asiftheyactuallyappearedasinfigures57and59.
Infigure60,thereisaridgemarked"A"whichentersononesideoftheimpressionand,afterrecurving,passesanimaginarylinedrawnfromthecoreCtodeltaD,andterminatesonthesamesideoftheimpressionfromwhichitentered,marked"B",thusfulfillingalltheconditionsrequiredinthedefinitionofaloop.XandYarethetypelines.Itwillbenotedinfigure61thatthereisaridgewhichentersononesideofthe[Pg20]impression,recurves,andpassesanimaginarylinedrawnfromthedeltatothecore.Itdoesnotterminateonthesidefromwhichitenteredbuthasatendencytodoso.Inthiscase,alltherequirementsoftheloophavebeenmet,andconsequentlyitisclassifiedassuch.
[Fig.60]
[Fig.61]
Figure62showsaridgeenteringononesideoftheimpression,recurving,andpassingbeyondanimaginarylinedrawnfromthedeltatothecore,althoughoppositefromthepatternshowninfigure61.Afterpassingtheimaginaryline,therecurvingridgedoesnotterminateonthesideoftheimpression
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 19/143
fromwhichitentered,butithasatendencytodoso,andthepatternis,therefore,aloop.
[Fig.62]
Infigure63,aridgeentersononesideoftheimpressionandthenrecurves,containingtworodswithinit,eachofwhichrisesashighastheshoulderoftheloop.Fromourstudyofcores,weknowthatthetopoftherodmoredistantfromthedeltaisthecore,buttherecurvingridgedoesnotpasstheimaginaryline.Forthatreasonthepatternisnotclassifiedasaloop,butisgiventhepreferentialclassificationofatentedarchduetothelackofoneofthelooprequisites.Theproperlocationofthecoreanddeltaisofextremeimportance,foranerrorinthelocationofeithermightcausethispatterntobeclassifiedasaloop.[Pg21]
[Fig.63]
Figure64reflectsasimilarcondition.
[Fig.64]
Infigure65,thereisaloopingridgeAwhichentersononesideoftheimpression.TheridgesBandCarethetypelines.Asdeterminedbyrulesalreadystated,thelocationofthecoreandthelocationofthedelta[Pg22]areshown,andifanimaginarylinewereplacedonthecoreanddelta,therecurvingridgeAwouldcrossit.Thisisanotherfigureshowingaridgewhichdoesnotterminateonthesideoftheimpressionfromwhichitenteredbuttendstodoso,and,therefore,isconsideredasaloop.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 20/143
[Fig.65]
Infigure66,wehaveaprintwhichissimilarinmanyrespectstotheonedescribedintheprecedingparagraph,butheretherecurvingridgeAcontinuesandtendstoterminateontheoppositesideoftheimpressionfromwhichitentered.Forthisreasonthepatternisnotaloop,butatentedarch.Therecurvingridgemusttouchorpasstheimaginarylinebetweendeltaandcoreandatleasttendtopassouttowardthesidefromwhichitentered,sothataridgecountofatleastonecanbeobtained.
[Fig.66]
Figure67showsaridgewhichentersononesideoftheimpressionand,afterflowingtowardthecenter,turnsorloopsonitselfandterminatesonthesamesidefromwhenceitentered.Thispatternwouldbeclassifiedasaloop.Thispatternshouldbedistinguishedfromthepatternappearinginfigure139.Carefulstudyofthepatterninfigure67revealsthatthecoreislocatedatCandthedeltaD.Theimaginarylinebetweenthesepointswillbecrossedbytheridgeformingaloop.Infigure139,thecoreislocatedontherecurveandanimaginarylinebetweenthedeltaandthecoredoesnotcrossaloopingridge.Figure139isthusclassifiedasatentedarch,aswillbeseenlater.
[Fig.67]
Figure68showsatthecenteroftheprintaridgewhichformsapocket.ItwillbenoticedthatridgeAdoesnotbeginontheedgeoftheprint,butthisisofnosignificance.TheridgeAwithinthepatternarearecurvesorloops,passingtheimaginarylinebetweenthedeltaandthecore,andtendstoterminatetowardthesamesideoftheimpressionfromwhenceitentered.Thisisalooppatternpossessingalloftherequirements.[Pg23]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 21/143
[Fig.68]
Infigures69and70,itwillbeobservedthatthereisaridgeenteringononesideofthepatternwhichrecurvesandthenturnsbackonitself.Thesepatternsaredifferentfromanyotherswhichhavebeenshowninthisrespectbutareclassifiedasloops.Ineachofthepatternsthecoreanddeltaaremarked"C"and"D".ThereadershouldtracethetypelinesinordertoascertainwhythedeltaislocatedatpointD,andthenapplythedeltarule.
[Fig.69]
[Fig.70]
Figure71isanexampleofloopsastheyappearontherolledimpressionportionofafingerprintcard.[Pg24]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 22/143
[Fig.71]
[Enlarge]
Ridgecounting
Thenumberofridgesinterveningbetweenthedeltaandthecoreisknownastheridgecount.ThetechnicalemployeesoftheFederalBureauofInvestigationcounteachridgewhichcrossesortouchesanimaginarylinedrawnfromthedeltatothecore.Neitherdeltanorcoreiscounted.Aredlineuponthereticuleofthefingerprintglassisusedtoinsureabsoluteaccuracy.Intheeventthereisabifurcationofaridgeexactlyatthepointwheretheimaginarylinewouldbedrawn,tworidgesarecounted.Wherethelinecrossesanisland,bothsidesarecounted.Fragmentsanddotsarecountedasridgesonlyiftheyappeartobeasthickandheavyastheotherridgesintheimmediatepattern.Variationsininkingandpressuremust,ofcourse,beconsidered.
Figures72to97andfigures98to101showvariouslooppatterns.Thereadershouldexamineeachonecarefullyinordertostudythecoresanddeltasandtoverifythecountwhichhasbeenplacedbeloweachpattern.[Pg25]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 23/143
[Pg26]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 24/143
[Pg27]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 25/143
[Pg28]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 26/143
[Pg29]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 27/143
[Figs.72101]
[Pg30]
Figure102isasketchreflectingthevarioustypesofridgeswhichtheclassifierwillencounterwhenengagingincountinglooppatterns.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 28/143
[Fig.102]
Infigure103,thelighterlinesarecausedbythesplittingorfrayingoftheridges.Sometimesingraineddirtwillcauseasimilarconditionbetweentheridges.Theselinesarenotconsideredridgesandshouldnotbecounted.
[Fig.103]
Infigure104,thedotisnotthedeltabecauseitisnotasthickandheavyastheotherridgesandmightnotbepresentifthefingerwerenotperfectlyinkedandprinted.
[Fig.104]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 29/143
Whenthecoreislocatedonaspikewhichtouchestheinsideoftheinnermostrecurvingridge,therecurveisincludedintheridgecountonlywhenthedeltaislocatedbelowalinedrawnatrightanglestothespike.
Figures105and106areexamplesofthisrule.
[Figs.105106]
IfthedeltaislocatedinareasA,therecurvingridgeiscounted.
IfthedeltaislocatedinareasB,therecurvingridgeisnotcounted.
[Pg31]
Radialandulnarloops
Theterms"radial"and"ulnar"arederivedfromtheradiusandulnabonesoftheforearm.Loopswhichflowinthedirectionoftheulnabone(towardthelittlefinger)arecalledulnarloopsandthosewhichflowinthedirectionoftheradiusbonearecalledradialloops.
Fortestpurposes,fingersoftherighthandmaybeplacedonthecorrespondingprintoftherighthandappearinginfigure71,anditwillbenoticedthatthesideofeachfingerwhichisnearertothethumbonthehandisalsonearertothethumbonthefingerprintcard.Placethefingersofthelefthandonthecorrespondingprintsofthelefthandshowninfigure71.Itwillbenoticedthatthearrangementoftheprintsonthecardisthereverseofthearrangementofthefingersonthehand.Theclassificationofloopsisbasedonthewaytheloopsflowonthehand(notthecard),sothatonthefingerprintcardforthelefthand,loopsflowingtowardthethumbimpressionareulnar,andloopsflowingtowardthelittlefingerimpressionareradial.[Pg32]
Theplainarch
Inplainarchestheridgesenterononesideoftheimpressionandflowortendtoflowouttheotherwithariseorwaveinthecenter.Theplainarchisthemostsimpleofallfingerprintpatterns,anditiseasilydistinguished.Figures107to118areexamplesoftheplainarch.Itwillbenotedthattheremaybevariousridgeformationssuchasendingridges,bifurcations,dotsandislandsinvolvedinthistypeofpattern,buttheyalltendtofollowthegeneralridgecontouri.e.,theyenterononeside,makeariseorwaveinthecenter,andflowortendtoflowouttheotherside.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 30/143
[Pg33]
[Pg34]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 31/143
[Figs.107118]
Figures119and120areexamplesofplainarcheswhichapproximatetentedarches.Also,figure121isaplainarchapproximatingatentedarchastherisingridgecannotbeconsideredanupthrustbecauseitisacontinuous,andnotanending,ridge.(Seefollowingexplanationofthetentedarch.)
[Figs.119121]
[Pg35]
Thetentedarch
Inthetentedarch,mostoftheridgesenterupononesideoftheimpressionandflowortendtoflowoutupontheotherside,asintheplainarchtypehowever,theridgeorridgesatthecenterdonot.Therearethreetypesoftentedarches:
Thetypeinwhichridgesatthecenterformadefiniteanglei.e.,90orless.
Thetypeinwhichoneormoreridgesatthecenterformanupthrust.Anupthrustisanendingridgeofanylengthrisingatasufficientdegreefromthehorizontalplanei.e.,45ormore.
Thetypeapproachingthelooptype,possessingtwoofthebasicoressentialcharacteristicsoftheloop,butlackingthethird.
Figures122to133areexamplesofthetentedarch.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 32/143
[Pg36]
[Pg37]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 33/143
[Figs.122133]
Figures122to124areofthetypepossessinganangle.
Figures125to129reflectthetypepossessinganupthrust.
Figures130to133showthetypeapproachingtheloopbutlackingonecharacteristic.
Tentedarchesandsomeformsoftheloopareoftenconfused.Itshouldberememberedbythereaderthatthemereconvergingoftworidgesdoesnotformarecurve,withoutwhichtherecanbenoloop.Ontheotherhand,therearemanypatternswhichatfirstsightresembletentedarchesbutwhichoncloseinspectionarefoundtobeloops,aswhereoneloopingridgewillbefoundinanalmostverticalpositionwithinthepatternarea,entirelyfreefromandpassinginfrontofthedelta.
Figure134isatentedarch.Theridgemarked"AA"inthesketchentersononesideoftheimpressionandflowstotheotherwithanacuteriseinthecenter.RidgeCstrikesintoAatpointBandshouldnotbeconsideredasabifurcatingridge.Theridgesmarked"DD"wouldformatentedarchiftherestofthepatternwereabsent.
[Fig.134]
[Pg38]
Figure135isasketchofapatternreflectingaridge,AB,enteringononesideoftheimpression,recurving,andmakingitsexitontheothersideoftheimpression.Thereadershouldstudythissketchcarefully.Itshouldbeborneinmindthattheremustbearidgeenteringononesideoftheimpressionandrecurvinginordertomakeitsexitonthesamesidefromwhichitentered,orhavingatendencytomakeitsexitonthatside,beforeapatterncanbeconsideredforpossibleclassificationasaloop.Thispatternisatentedarchoftheupthrusttype.TheupthrustisC.ThereisalsoanangleatE.Dcannotbetermedasadelta,astheridgetotheleftofDcannotbeconsideredatypelinebecauseitdoesnotdivergefromtheridgetotherightofDbutturnsandgoesinthesamedirection.
[Fig.135]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 34/143
Inconnectionwiththetypesoftentedarches,thereaderisreferredtothethirdtype.Thisformoftentedarch,theonewhichapproachestheloop,mayhaveanycombinationoftwoofthethreebasicloopcharacteristics,lackingthethird.Thesethreeloopcharacteristicsare,torepeat:
Asufficientrecurve.
Adelta.
Aridgecountacrossaloopingridge.
Itmustberememberedthatarecurvemustbefreeofanyappendageabuttinguponitatarightanglebetweentheshoulders,andatrueridgecountisobtainedonlybycrossingaloopingridgefreely,withawhitespaceinterveningbetweenthedeltaandtheridgetobecounted.
Figures136and137aretentedarcheshavingloopformationswithinthepatternareabutwithdeltasupontheloops,byreasonofwhichitisimpossibletosecurearidgecount.Thetypelinesrunparallelfromtheleftinfigures136and137.Thesetentedarcheshavetwooftheloopcharacteristics,recurveanddelta,butlackthethird,theridgecount.[Pg39]
[Figs.136137]
Infigure138,thereaderwillnotethesimilaritytothefigures136and137.Theonlydifferenceisthatinthisfigurethetypelinesarerunningparallelfromtheright.Itwillbenotedfromthesethreepatternsthatthespacesbetweenthetypelinesattheirdivergenceshownothingwhichcouldbeconsideredasdeltaformationsexcepttheloopingridges.Suchpatternsareclassifiedastentedarchesbecausetheridgecountnecessaryforaloopislacking.
[Fig.138]
Figure139isanexampleofatentedarch.Inthispattern,iftheloopingridgeapproachedtheverticalitcouldpossiblybeaonecountloop.Oncestudied,however,thepatternpresentsnorealdifficulty.Therearenoridgesinterveningbetweenthedelta,whichisformedbyabifurcation,andthecore.Itwillbenotedthatthecore,inthiscase,isatthecenter[Pg40]oftherecurve,unlikethoseloopswhicharebroadsidetothedeltaandinwhichthecoreisplacedupontheshoulder.Thispatternhasarecurveandaseparatedelta,butitstilllackstheridgecountnecessarytomakeitaloop.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 35/143
[Fig.139]
Figures140and141areexamplesoftentedarches.Thesetwofiguresaresimilarinmanyways.Eachoftheseprintshasthreeabruptendingridgesbutlacksarecurvehowever,infigure141adeltaispresentinadditiontothethreeabruptendingridges.Thisconditiondoesnotexistinfigure140,wherethelowerendingridgeisthedelta.
[Figs.140141]
Wheninterpretingapatternconsistingoftwoendingridgesandadeltabutlackingarecurve,donotconfusetheridgecountofthetentedarchwiththatoftheridgecountfortheloop.Theridgecountofthetentedarchismerelyaconventionoffingerprinting,afictiondesignedtofacilitateascientificclassificationoftentedarches,andhasnoconnectionwithaloop.Toobtainatrueridgecounttheremustbealoopingridgewhichiscrossedfreelybyanimaginarylinedrawnbetweenthedeltaandthecore.Theridgecountreferredtoassuchinconnectionwiththetentedarchespossessingendingridgesandnorecurveisobtainedbyimaginingthattheendingridgesarejoinedbyarecurveonlyforthepurposeoflocatingthecoreandobtainingaridgecount.Ifthispointissecureinthemindoftheclassifier,littledifficultywillbeencountered.
Figures140and141,then,aretentedarchesbecausetheyhavetwoofthecharacteristicsofaloop,deltaandridgecount,butlackthethird,therecurve.
Figure142isaloopformationconnectedwiththedeltabuthavingnoridgecountacrossaloopingridge.Bydrawinganimaginarylinefromthecore,whichisatthetopoftherodinthecenterofthepattern,tothedelta,itwillbenotedthatthereisnorecurvingridgepassingbetweenthisrodandthedeltaand,therefore,noridgecountcanresult.Thispatternisclassifiedasatentedarch.Theremustbeawhitespacebetweenthedeltaandthefirstridgecounted,oritmaynotbecounted.Figure143isalsoatentedarchbecausenoridgecountacrossaloopingridgecanbeobtained,thebifurcationsbeingconnectedtoeachotherand[Pg41]totheloopinastraightlinebetweendeltaandcore.Theloopingridgeisnotcrossedfreely.Nowhitespaceintervenesbetweenthedeltaandtheloop.Thesepatternsaretentedarchesbecausetheypossesstwoofthecharacteristicsofaloop,adeltaandarecurve,butlackthethird,aridgecountacrossaloopingridge.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 36/143
[Figs.142143]
Figure144isatentedarchcombiningtwoofthetypes.Thereisanangleformedbyridgeaabuttinguponridgeb.Therearealsotheelementsofthetypeapproachingaloop,asithasadeltaandridgecountbutlacksarecurve.
[Fig.144]
Figures145to148aretentedarchesbecauseoftheanglesformedbytheabuttingridgesatthecenterofthepatterns.
[Figs.145148]
Figure149isatentedarchbecauseoftheupthrustpresentatthecenterofthepattern.Thepresenceoftheslightestupthrustatthecenteroftheimpressionisenoughtomakeapatternatentedarch.[Pg42]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 37/143
[Fig.149]
Anupthrustmustbeanendingridge.Ifcontinuousasinfigure150,noanglebeingpresent,thepatternisclassifiedasaplainarch.
[Fig.150]
Figures151to153areplainarches.Figure154isatentedarch.
[Figs.151154]
Figure155isaplainarchbecauseitisreadilyseenthattheapparentupthrustAisacontinuationofthecurvingridgeB.Figure156isatentedarchbecauseridgeAisanindependentupthrust,andnotacontinuationofridgeB.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 38/143
[Figs.155156]
[Pg43]
Figures157and158areplainarches.Figure158cannotbesaidtobealoopingridge,becausebydefinitionaloopmustpassoutortendtopassoutuponthesidefromwhichitentered.Thisapparentlooppassesoutupontheoppositesideandcannotbesaidtotendtoflowoutuponthesameside.
[Figs.157158]
Infigures159and160,thereareendingridgesrisingataboutthesamedegreefromthehorizontalplane.
[Figs.159160]
Figure159,however,isaplainarch,while160isatentedarch.Thisdifferentiationisnecessarybecause,ifthefirstpatternwereprintedcrookedlyuponthefingerprintcardsothattheendingridgewasnearerthehorizontalplane,therewouldbenowaytoascertainthetruehorizontalplaneofthepattern(ifthefissureofthefingerdidnotappear).Inotherwords,therewouldbenomeansofknowingthattherewassufficientrisetobecalledanupthrust,sothatitissafetoclassifytheprintasaplainarchonly.Infigure160,however,nomatterhowitisprinted,thepresence[Pg44]ofasufficientrisecouldalwaysbeascertainedbecauseofthespaceinterveningbetweentheendingridgeandtheridgeimmediatelybeneathit,sothatitissafetoclassifysuchapatternasatentedarch.Thetestis,iftheridgesonbothsidesoftheendingridgefollowitsdirectionorflowtrend,theprintmaybeclassifiedasaplainarch.If,however,theridgesononlyonesidefollowitsdirection,theprintisatentedarch.
Anupthrust,then,mustnotonlybeanendingridgerisingatasufficientdegreefromthehorizontalplane,buttheremustalsobeaspacebetweentheendingridgeandtheridgeimmediatelybeneathit.This,however,isnotnecessaryforashortupthrustorspike,oranyupthrustwhichrisesperpendicularly.
Inconnectionwiththeproperclassificationtobeassignedtothoseborderlinelooptentedarchcaseswhereanappendageorspikeisthrustingoutfromtherecurve,itisnecessarytorememberthatanappendageoraspikeabuttinguponarecurveatrightanglesinthespacebetweentheshouldersofaloopontheoutsideisconsideredtospoiltherecurve.
Iftheappendingridgeflowsofftheloopingridgesmoothlyinsuchawaythatitformsabifurcationandnotanabutmentoftworidgesatarightangle,therecurveisconsideredasremainingintact.Thetestistotracetheloopingridgetowardtheappendage,andif,whenitisreached,thetracingmaybecontinuedasreadilyupontheappendageasupontheloopingridge,withnosudden,sharpchangeofdirection,the
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 39/143
recurveissufficient.Figures161to184shouldbestudiedwiththisinmind.
[Pg45]
[Pg46]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 40/143
[Figs.161184]
[Pg47]
Figures185to190showadditionalexamplesoftentedarches.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 41/143
[Figs.185190]
Thereasonthatfigure185isgiventheclassificationofatentedarchisbecauseofthepresenceofallthelooprequirementswiththeexceptionofone,whichistherecurve.Inthispatternappearthreeendingridges.[Pg48]Thelowestendingridgeprovidesthedelta,andtheothertwobytheconventionexplainedpreviously,providetheridgecount.Itisatentedarch,then,ofthetypeapproachingtheloop,withtwoofthecharacteristics,butlackingthethird,arecurve.Figures186and187aretentedarchesofthesametype.Acloseexaminationoftheseprintswillrevealthatwhentheimaginarylineisdrawnbetweendeltaandcorenoridgecountacrossaloopingridgecanbeobtained.Itmustberememberedthatthecoreofaloopmaynotbeplacedbelowtheshoulderline.Lackingoneofthethreecharacteristicsofaloop,thesepatternsmustbeclassifiedastentedarches.Whenfigure188isexamined,itwillbenoticedthattherecurveisspoiledbytheappendageabuttinguponitbetweentheshouldersatarightangle,soitmustalsobeclassifiedwiththetentedarches.Infigure189,theonlypossibledeltamustbeplacedupontheloopingridge,thuspreventingaridgecountalthoughdeltaandrecurvearepresent.Figure190isassignedtheclassificationofatentedarch.Oneoftherequirementsofalooptypeisthattheridgeentersononeside,recurves,andmakesitsexitonthesidefromwhichitentered.This,ofcourse,makesitnecessary[Pg49]thattheridgepassbetweenthedeltaandthecore.Itwillbenotedfromthisfigurethatalthoughthisridgepassesbetweenthedeltaandthecore,itdoesnotshowanytendencytomakeitsexitonthesidefromwhichitentered,andthereforetheloopclassificationisprecluded,anditisatentedarch.
Thewhorl
Thepatternstowhichnumericalvaluesareassignedinderivingthe"primary"intheextensionoftheHenrySystemoffingerprintclassificationusedbytheFederalBureauofInvestigationarethewhorltypepatterns,whichoccurinabout30percentofallfingerprints.
Thewhorlisthattypeofpatterninwhichatleasttwodeltasarepresentwitharecurveinfrontineach.Figures191to193reflecttheminimumrequirementsforthewhorl.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 42/143
[Figs.191193]
Itisimportanttonotethattheabovedefinitionisverygeneralhowever,thispatternmaybesubdividedforextensionpurposesinlargegroupswherewhorlsarepredominant.Eventhoughthisextensionmaybeused,alltypesofwhorlsaregroupedtogetherunderthegeneralclassificationof"Whorl"andaredesignatedbytheletter"W".
Theaforementionedsubdivisionsareasfollows:ThePlainWhorl,TheCentralPocketLoop,TheDoubleLoop,andTheAccidental.
Theplainwhorl
The"plainwhorl"consistsofthesimplestformofwhorlconstructionandisthemostcommonofthewhorlsubdivisions.Itisdesignatedbythesymbol"W"forbothgeneralclassificationandextensionpurposes.
Theplainwhorlhastwodeltasandatleastoneridgemakingacompletecircuit,whichmaybespiral,oval,circular,oranyvariantofacircle.Animaginarylinedrawnbetweenthetwodeltasmusttouchorcrossatleastoneoftherecurvingridgeswithintheinnerpatternarea.Arecurvingridge,however,whichhasanappendageconnectedwithitin[Pg50]thelineofflowcannotbeconstruedasacircuit.Anappendageconnectedatthatpointisconsideredtospoiltherecurveonthatside.
Figures194to211aretypicalexamplesoftheplainwhorltype.Figure212is,however,aloop,asthecircuitisspoiledononesidebyanappendage.
[Pg51]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 43/143
[Pg52]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 44/143
[Figs.194212]
[Pg53]
Centralpocketloop
Withinthewhorlgroup,thesubclassificationtype"centralpocketloop"isusedforextensionpurposesonly.Ingeneralclassificationitisdesignatedbytheletter"W".Figures213to236arecentralpocketloops.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 45/143
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 46/143
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 47/143
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 48/143
[Figs.213236]
Thecentralpocketlooptypeofwhorlhastwodeltasandatleastoneridgemakingacompletecircuit,whichmaybespiral,oval,circular,oranyvariantofacircle.Animaginarylinedrawnbetweenthetwodeltasmustnottouchorcrossanyoftherecurvingridgeswithintheinnerpatternarea.Arecurvingridge,however,whichhasanappendageconnectedwithitinthelineofflowandonthedeltasidecannotbeconstruedasacircuit.Anappendageconnectedatthatpointisconsideredtospoiltherecurveonthatside.
Inlieuofarecurveinfrontofthedeltaintheinnerpatternarea,anobstructionatrightanglestothelineofflowwillsuffice.
Itisnecessarythattheinnerlineofflowbefixedartificially.Theinnerlineofflowisdeterminedbydrawinganimaginarylinebetweentheinnerdeltaandthecenteroftheinnermostrecurveorloopingridge.
Inthecentralpocketloop,oneormoreofthesimplerecurvesoftheplainlooptypeusuallyrecurveasecondtimetoformapocketwithintheloop.Thesecondrecurve,however,neednotbeacontinuationoforevenconnectedwiththefirst.Itmaybeanindependentridge.
Ifnosecondrecurveispresent,anobstructionatrightanglestotheinnerlineofflowisacceptableinlieuofit.Anobstructionmaybeeithercurvedorstraight.Adot,ofcourse,maynotbeconsideredanobstruction.
Thedefinitiondoesnotrequirearecurvetocrossthelineofflowatrightangles.Theangletestneedstobeappliedtoobstructionsonly.
Therecurveorobstructionofthecentralpocketloop,asthatoftheplainwhorl,mustbefreeofanyappendageconnectedtoitatthepointcrossedbythelineofflowandonthedeltaside.Anappendageatthatpointisconsideredtospoiltherecurveorobstruction.
[Pg58]
Figures237and238arealsocentralpocketloopsdespitetheappendagesconnectedtotherecurves,
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 49/143
becausetheyarenotconnectedatthepointcrossedbythelineofflow.
[Figs.237238]
Figure239,althoughpossessingarecurve,isclassifiedasaloopbecausetheseconddeltaislocatedontheonlyrecurvingridge.
[Fig.239]
[Pg59]
Figures240to244,althoughpossessingonedeltaandadeltaformation,areclassifiedasloopsbecausetheobstructionsdonotcrossthelineofflowatrightangles.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 50/143
[Figs.240244]
[Pg60]
Figures245to254havetwodeltasandoneormorerecurves,buttheyareclassifiedasloopsbecauseeachrecurveisspoiledbyanappendageconnectedtoitatthepointcrossedbythelineofflow.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 51/143
[Figs.245254]
[Pg61]
Doubleloop
Withinthewhorlgroup,thesubclassificationtype"doubleloop"isusedforextensionpurposesonly.Ingeneralclassificationitisdesignatedbytheletter"W".
Thedoubleloopconsistsoftwoseparateloopformations,withtwoseparateanddistinctsetsofshoulders,andtwodeltas.
Theword"separate,"asusedhere,doesnotmeanunconnected.Thetwoloopsmaybeconnectedbyanappendingridgeprovidedthatitdoesnotabutatrightanglesbetweentheshouldersoftheloopformation.Theappendagerulefortheloopappliesalsotothedoubleloop.Anappendageabuttinguponaloopatrightanglesbetweentheshouldersisconsideredtospoiltheloop,whileanappendagewhichflowsoffsmoothlyisconsideredtoleavetherecurveintact.
Thefactthattheremustbetwoseparateloopformationseliminatesfromconsiderationasadoubleloopthe"S"typecore,theinterlockingtypecore,andtheformationwithoneloopinsideanother.
Theloopsofadoubleloopdonothavetoconformtotherequirementsoftheloop.Inotherwords,noridgecountisnecessary.
Itisnotessentialthatbothsidesofaloopbeofequallength,northatthetwoloopsbeofthesamesize.Neitherisitmaterialfromwhichsidetheloopsenter.
ThedistinctionbetweentwinnedloopsandlateralpocketloopsmadebyHenryandadoptedbyotherauthorshasbeenabandonedbytheFederalBureauofInvestigationbecauseofthedifficultyinlocatingandtracingtheloops.Bothtypeshavebeenconsolidatedundertheclassification"doubleloop."
Figures255to266aredoubleloops.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 52/143
[Pg62]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 53/143
[Figs.255266]
[Pg63]
Figure267isaplainwhorl.Itisnotclassifiedasadoubleloopasonesideofoneloopformsthesideoftheother.Figure268isaplainloop.Itisnotadoubleloopbecausealloftherecurvesoftheloopontherightarespoiledbyappendages.
[Figs.267268]
[Pg64]
Accidental
Withinthewhorlgroupthesubdivisiontype"accidental"isusedforextensionpurposesonly.Ingeneralclassificationitisdesignatedbytheletter"W"andforextensionpurposesbytheletter"X".
Theaccidentalwhorlisapatternconsistingofacombinationoftwodifferenttypesofpattern,withtheexceptionoftheplainarch,withtwoormoredeltasorapatternwhichpossessessomeoftherequirementsfortwoormoredifferenttypesorapatternwhichconformstononeofthedefinitions.Itmaybeacombinationofloopandtentedarch,loopandwhorl,loopandcentralpocketloop,doubleloopandcentralpocketloop,orothersuchcombinations.Theplainarchisexcludedasitisrathertheabsenceofpatternthanapattern.Underneatheverypatternthereareridgesrunningfromonesidetotheother,sothatifitwerenotexcludedeverypatternbuttheplainarchwouldbeanaccidentalwhorl.
Thissubclassificationalsoincludesthoseexceedinglyunusualpatternswhichmaynotbeplacedbydefinitionintoanyotherclasses.
Figures269to271areaccidentalscombiningaloopwithatentedarch.[Pg66]Figures272to276combinealoopandaplainwhorlorcentralpocketloop.Figure277combinesaloopandadoubleloop.Figure278combinesaloopandaplainarch,soitisclassifiedasaloop.Figure279combinesaloopandatentedarch.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 54/143
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 55/143
[Figs.269279]
Somewhorlsmaybefoundwhichcontainridgesconformingtomorethanoneofthewhorlsubdivisionsdescribed.Insuchcases,theorderofpreference(ifanypracticaldistinctionneedbemade)shouldbe:(1)accidental,(2)doubleloop,(3)centralpocketloop,(4)plainwhorl.
Whorltracing
Thetechniqueofwhorltracingdependsupontheestablishmentofthefocalpointsthedeltas.Everywhorlhastwoormore.Whenthedeltashavebeenlocated,theridgeemanatingfromthelowersideorpointoftheextremeleftdeltaistraceduntilthepointnearestoroppositetheextremerightdeltaisreached.Thenumberofridgesinterveningbetweenthetracingridgeandtherightdeltaarethencounted.Iftheridgetracedpassesinsideof(above)therightdelta,andthreeormoreridgesintervenebetweenthetracingridgeandthedelta,thetracingisdesignatedasan"inner"I(fig.280).Iftheridgetracedpassesoutside(below)the[Pg67]rightdelta,andthreeormoreridgesintervenebetweenthetracingridgeandtherightdelta,thetracingisdesignatedasan"outer"O(fig.281).Allothertracingsaredesignatedas"meeting"M(figs.282to287).
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 56/143
[Figs.280287]
[Pg68]
Tracingbeginsfromtheleftdelta.Innoinstanceisatracingtobeginonatypeline.Infigure288,tracingbeginsattheshortridgewhichistheleftdelta.Itistruethatinasmuchastheshortridgeendsimmediatelythetypelineisnextfollowed,butthisisonlybecausethetypelineisthenextlowerridge.Itsstatusasatypelineisindependentandhasnobearingonthefactthatitisbeingtraced.Thispointisillustratedfurtherinfigure289.Thispatternshowsaninnertracing.Itwillbenotedthatthedeltaisatthepointonthefirstrecurvenearesttothecenterofthedivergenceofthetypelines.Itwillbefurthernotedthattracingbeginsatthepointofdeltaontheleftandcontinuestowardtheright,passinginsideoftherightdelta,withthreeridgesinterveningbetweenthetracingridgeandtherightdelta.Thisshowsthetracingtobeaninnertracing.If,inthiscase,thetypelineweretraced(whichwouldbetheincorrectprocedure),onlytworidgeswouldintervenebetweenthetracingridgeandtherightdelta,resultinginanerroneousmeetingtracing.Figure290isanotherexampleoftheapplicationofthisrule.Thisillustrationisalsoaninnerwhorl.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 57/143
[Figs.288290]
Whentheridgetracedendsabruptly,anditisdeterminedthattheridgedefinitelyends,thetracingdropsdowntothepointonthenextlowerridgeimmediatelybeneaththepointwheretheridgeaboveends,continuingfromthere.Figure291,therefore,isanouterwhorl.
[Fig.291]
Inthisconnectionitshouldbenotedthattherulefordroppingtothenextlowerlineappliesonlywhentheridgedefinitelyends.Shortbreaksinaridgewhichmaybeduetoimproperinking,thepresenceofforeignmatterontheridges,enlargedpores,disease,orwornridgesshouldnotbeconsideredasdefiniteridgeendings.Thedeterminationofwhatconstitutesadefiniteendingwilldepend,ofcourse,uponthegoodjudgmentoftheclassifier.Whenthequestionarisesastowhetherabreakencoun[Pg69]teredintheridgetracingisadefiniteending,orwhethertherehasbeeninterferencewithanaturalimpression,thewholepatternshouldbeexaminedtoascertainwhethersuchbreaksaregeneralthroughoutthepattern.Iftheyarefoundtobecommon,considerationshouldthenbegiventothepossibilitythatthebreakisnotadefiniteridgeending.Appropriatereferencetracingshouldbedoneinallsuchcases.
Whenevertheridgetracedbifurcates,therulefortracingrequiresthatthelowerlimborbranchproceedingfromthebifurcationbefollowed.Thisisillustratedin292.
[Fig.292]
Accidentalsoftenpossessthreeormoredeltas.Intracingthemonlytheextremedeltasareconsidered,thetracingbeginningattheextremeleftdeltaandproceedingtowardtheextremerightdelta,asillustratedinfigure293.[Pg70]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 58/143
[Fig.293]
Inadoublelooporaccidentaltheproblemofwheretostoptracingissometimespresented.Theruleis,whenthetracingpassesinsideoftherightdelta,stopatthenearestpointtotherightdeltaontheupwardtrend,asinfigure294.Ifnoupwardtrendispresent,continuetracinguntilapointoppositetherightdelta,orthedeltaitself,isreached(figs.295and296).
[Figs.294296]
[Pg71]
CHAPTERIII
QuestionablePatterns
Nomatterhowdefinitefingerprintrulesandpatterndefinitionsaremade,therewillalwaysbepatternsconcerningwhichthereisdoubtastotheclassificationtheyshouldbegiven.Theprimaryreasonforthisisthefactthatprobablynotwofingerprintswilleverappearwhichareexactlyalike.Otherreasonsaredifferencesinthedegreeofjudgmentandinterpretationoftheindividualclassifyingfingerprints,thedifferenceintheamountofpressureusedbythepersontakingtheprints,andtheamountorkindofinkused.Nothingcanbedoneaboutfaultyinkingorpressureoncetheprintsaretaken.Thepatternswhicharequestionablemerelybecausetheyseemtohavecharacteristicsoftwoormoretypescanbeclassifiedbystrictadherencetothedefinitionsindeducingapreference.Thefollowingsectionisdevotedtosuchpatternswithanexplanationofeach.
Figure297hastwoloopformations.Theoneontheleft,however,hasanappendageabuttingupontheshouldersofitsrecurveatarightangle.Theleftportionoftheimpression,therefore,isofthetentedarchtype.Thecombinationoftwodifferenttypesofpatternswouldbeclassifiedinthewhorlgroup(accidental),butthisimpressionhasonlytheonedelta.Therightportionofthepatterndetailcontainsatrueloopwhichfulfillsallthelooprequirements,i.e.,asufficientrecurve,adelta,andaridgecountacrossaloopingridge.Inthechoiceexistingbetweenatentedarchandaloop,preferenceisgiventotheloopclassificationandthisimpressionwouldbeclassifiedasaloop.[Pg72]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 59/143
[Fig.297]
Figure298,ataglance,seemstofulfilltherequirementsofawhorl(twodeltasandaridgemakingacompletecircuit).Thepartofthecircuitinfrontoftherightdelta,however,cannotbeconstruedasarecurvingridgebecauseoftheappendageabuttinguponitinthelineofflow.Thispattern,therefore,isaonecountloop.
[Fig.298]
Figure299isaverydifficultandunusualpattern.Ithascharacteristicsofthreetypes,thewhorl,theloop,andthetentedarch.Itisgiventhepreferenceofanaccidentaltypeofwhorl(loopoveratentedarch).Thispatternshouldbereferencedbothasaloopandasatentedarch.
[Fig.299]
Figure300isshownforthepurposeofexplainingthatinthewhorl,asthisprintis,appendagesatthetopoftherecurvewillnotspoiloraffecttherecurve.Hence,theimpressionisagoodwhorlofthecentralpocketlooptypeandneedsnoreference.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 60/143
[Fig.300]
Figure301isclassifiedasawhorlofthedoublelooptype.Therearepresenttwodistinctloopsandtwodeltas(therightdeltaisnotpresentastheimpressionwasnotrolledsufficiently).Thepatternisunusualbecausetheloopsaresidebysideandflowinginthesamedirection.Thetracingisaninnertracing.[Pg73]
[Fig.301]
Figure302shouldpresentnodifficulty.Itisclassifiedasaplainarchforitsridgeconstructionfollowstheruleofaplainarch,i.e.,"enteronesideandflowortendtoflowtotheother."
[Fig.302]
Figure303isaplainarch.Thedotatthecenterisnotelongatedenoughtobeconsideredanupthrust.Adot,eventhoughasthickandheavyasthesurroundingridges,isnotconsideredforanypurposebutridgecountingorfixingadelta.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 61/143
[Fig.303]
Figure304isapatternsomewhatsimilartothepreviousillustration.Asindicatedbefore,dotsareconsideredasridgesonlyinridgecountingandfixingadelta.Thispattern,therefore,mustbeclassifiedasaplainarch,ratherthanatentedarchwithtwoendingridgesandadeltaformation.
[Fig.304]
Figure305,althoughshowinganappendageuponeachrecurveontheleftside,isclassifiedasawhorlofthecentralpocketlooptype,withtwodeltasandarecurveinfrontofeach.Tospoiltherecurveofawhorltheappendagemustbeconnectedtotherecurveatthepointofcontactwiththelineofflow.
[Fig.305]
[Pg74]Infigure306,theimpressionhastwoequallygoodloopformations.Asithasbutonedelta,itcannotbeclassifiedasawhorlofthedoublelooptypenorasaloopsinceitwouldbedifficulttomakeapreferentialchoicebetweenthetwoloopingridges.Itisarbitrarilygiventheclassificationofatentedarch.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 62/143
[Fig.306]
Infigure307,thedifficultyliesinlocatingthedelta.Theonlyridgesansweringthedefinitionoftypelines(ridgesrunningparallelandthendivergingtoenclosethepatternarea)havethreeendingridgesbetweenthem.Thetypelines,thedelta,andthecorearelocatedasindicated.Thepatternisclassifiedasasixcountloop.
[Fig.307]
Figure308isclassifiedasatentedarch,althoughitappearsatfirstglancetobealoop.Closerinspectionshowsthattheloopingridgedoesnottendtogooutthesidefromwhichitenteredbutratherseemstoproceeddownwardendinginanabutmentformingadefiniteangleof90.
[Fig.308]
[Pg75]
Infigure309,animpressionisshownwhichatfirstappearstobealoop.Closerinspectionwillshowthatoneoftheelementsofthelooptypeismissing,namely,aridgecountacrossaloopingridgeforitistobeborneinmindthattherecurveoftheinnermostloopshouldbefreeofappendagesabuttingbetweentheshouldersatrightangles.Thecore,inthisillustration,therefore,isplacedwheretheappendageoftheinnermostlooptouchesthenextridgewhichisagoodrecurve.Ifanimaginarylineisplacedbetweendeltaandcore,itwillbeseenthattherearenointerveningridgeshence,thereisnoridgecount.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 63/143
[Fig.309]
Figure310isapatternwhichcontainstwoelementsofaloopbutlacksthethird.Itisclassifiedasatentedarch.Thusanimpressionhavingadeltaandarecurve,butnothavingaridgecountacrossaloopingridge,fallsintothisclassification.
[Fig.310]
Itwillbenoticedthatalthoughthispatternhastheresemblanceofaplainarch,thecenteroftheimpressionactuallycontainsapartiallyformedloop.Arecurvingridgeentersfromtherightsideandexitsinthesamedirection.Adeltaalsoappearsjustbelowtherecurve.Inattempting[Pg76]toobtainaridgecount,itisseenthattheimaginarylinedrawnbetweenthedeltaandthecorerunsdirectlyalongtheridgeemanatingfromtheformerandwhichisjoinedontothesideoftherecurvingridge.Forthisreason,noridgecountispossible.
Figure311isatentedarch.Therearethreeloopformations,eachoneofwhichisspoiledbyanappendageabuttinguponitsrecurvebetweentheshouldersatarightangle.Itcannotbeclassifiedasanaccidentalasthepatternsareallofthesametype,i.e.,tentedarches.Anaccidentaltypeofwhorlisacombinationoftwoormoredifferenttypesofpatternsexclusiveoftheplainarch.
[Fig.311]
Figure312isaloop.Itcannotbeclassifiedasawhorlofthedoublelooptypebecausetheformationabovethelowerloopistoopointedanditalsohasanappendageabuttinguponitatarightangle.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 64/143
[Fig.312]
Figure313atfirstglanceappearstobeawhorlofthedoublelooptype.Uponcloserinspection,however,itwillbenoticedthattherearenodeltaformationsotherthanontherecurves.Thereare,then,twotentedarchformations.Astwopatternsofthesametypecannotformanaccidentalwhorl,theimpressionmustbeclassifiedasatentedarch.[Pg77]
[Fig.313]
Figure314isanaccidentalwhorl,combiningaloopandatentedarch.Thetentedarchisdirectlybeneaththeinnermostloop,andisoftheupthrusttype.
[Fig.314]
Figure315consistsofaloopoveradotwithanapparentseconddelta.Thispatternmustbeclassifiedasaloop,asadotmaynotbeconsideredanupthrustunlesselongatedvertically.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 65/143
[Fig.315]
Eventhoughadotmaybeasthickandheavyasthesurroundingridges,itmaybeconsideredonlyinridgecountingorfixingadelta.
Figure316atfirstglanceappearstobeanaccidentalwhorl,butoncloserinspectionitprovestobealoop.Althoughtherearethreedeltaformationspresent,itshouldbeobservedthatrecurvingridgesappearinfrontofonlyone(D1).
[Fig.316]
Figure317hasthegeneralappearanceofaloop.TheloopingridgeA,atthecenter,hasanappendageBabuttinguponitsrecurve.Theabutmentisatrightanglesandthereforespoilstherecurve.Thepatternisatentedarch.[Pg78]
[Fig.317]
Figure318isatentedarchwhichapproachesboththeloopandthewhorltypepatterns.Itcannotbeconsideredawhorl,however,astherecurveontheleftisspoiledbyanappendage(figs.58and59).Norcanitbealoopbecausethereisnoridgecountacrossaloopingridge.Thepattern,then,isatentedarchofthetypepossessingtwoofthebasiccharacteristicsoftheloopandlackingthethird.Thedeltaandthesufficientrecurvearepresentbuttheridgecountismissing.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 66/143
[Fig.318]
Figure319seemsatfirstglancetobeadoubleloop.Itwillbenoted,however,thattheinnerdeltaformationwouldbelocatedupontheonlyloopingridgeoftheupperloopformation.Sincethedeltawouldbelocatedontheonlyrecurve,thisrecurvingridgeiseliminatedfromconsideration.Thepatternisclassifiedasaloop.
[Fig.319]
Figure320isaloopoftwocounts,withthedeltaatB.Thereisaridgemakingacompletecircuitpresent,butpointAcannotbeusedasadeltabecauseitanswersthedefinitionofatypeline.Itshouldbeconsideredadeltaonlyifitpresentedanangularformation.Placingthedeltaupontherecurvewouldspoilthatrecurve.
[Fig.320]
Figure321showstwoseparateloopingridgeformationsappearingsidebysideanduponthesamesideofthedelta.Thecoreinsuchcaseisplaceduponthenearershoulderofthefartherloopingridgefromthedelta,thetwoloopingridgesbeingconsideredasoneloopwithtworodsrisingashighastheshoulder.Theridgecountwouldbefour(fig.49).
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 67/143
[Fig.321]
Figure322isanaccidentalwhorl.Itisclassifiedthusbecauseitcontainselementsofthreedifferentpatterns,theloop,thedoubleloop,andtheaccidental.Insuchcasetheorderofpreferencegoverns.ThedeltaattheleftispointA.ThedeltaattherightispointC.Thispointbecomesthedeltasinceitisthepointnearestthecenterofthedivergenceofthetypelines.PointBiseliminatedfromconsiderationasadeltasincetypelinesmaynotproceedfromabifurcationunlesstheyflowparallelafterthebifurcationandbeforediverging.[Pg79]
[Fig.322]
[Pg80]
Figure323isaloop.Therearetwodeltaformationsbutthedotscannotbeconsideredasobstructionscrossingthelineofflowatrightangles.Thisprecludestheclassificationofthecentralpocketlooptypeofwhorl.
[Fig.323]
Figure324isaloop,thetworecurvingridgeshaveappendagesandareconsideredspoiled.Thepatterncannot,therefore,beawhorleventhoughtwodeltaformationsarepresent.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 68/143
[Fig.324]
Figure325isclassifiedasatentedarch.Ifexaminedcloselythepatternwillbeseentohaveanappendageabuttingatarightanglebetweentheshouldersofeachpossiblerecurve.Thusnosufficientrecurveispresent.
[Fig.325]
Figure326isaplainarch.Thereispresentnoanglewhichapproachesarightangle.PointsA,B,andXaremerelybifurcationsratherthananabutmentoftworidgesatanangle.
[Fig.326]
Figure327isatentedarch,notbecauseofthedot,however,asitcannotbeconsideredanupthrust.Thetentedarchisformedbytheanglemadewhenthecurvingridgeabovethedotabutsupontheridgeimmediatelyunderandtotheleftofthedot.[Pg81]
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 69/143
[Fig.327]
Figure328consistsoftwoseparateloopingridgeformationsinjuxtapositionuponthesamesideofacommondelta.Thispatterncannotbecalledadoubleloopasthereisnoseconddeltaformation.Inordertolocatethecore,thetwoloopingridgesshouldbetreatedasoneloopwithtworodsinthecenter.Thecoreisthusplacedonthefarrod(actuallyontheleftshoulderofthefarloop),resultinginaridgecountoffour(fig.49).
[Fig.328]
Figure329isaloopofthreecounts.Itcannotbeclassifiedasawhorlastheonlyrecurveisspoiledbytheappendageabuttinguponitatthepointofcontactwiththelineofflow.
[Fig.329]
Figure330isaplainarchasthereisnoupthrust(anupthrustmustbeanendingridge),nobackwardloopingturn,andnotworidgesabuttinguponeachotheratasufficientangle.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 70/143
[Fig.330]
Figure331isaplainarch.Theendingridgeatthecenterdoesnotriseatasufficientangletobeconsideredanupthrust,anditdoesnotquitemeettheridgetowardwhichitisflowingandthereforeformsnoangle.[Pg82]
[Fig.331]
Figure332isaplainarch.Therearetwoendingridges,butnoseparatedeltaformationispresent.
[Fig.332]
Figure333isaplainarch.Therisingridgeatthecenteriscurvedatthetopformingnoangle,anddoesnotconstituteanupthrustbecauseitisnotanendingridge.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 71/143
[Fig.333]
Figure334isawhorlofthedoublelooptype.Twoloopsandtwodeltasarepresent.Itisunusualbecausetheloopsarejuxtaposedinsteadofoneflowingovertheother,andonedeltaisalmostdirectlyovertheother.Thetracingisameetingtracing.
[Fig.334]
Figure335isatentedarch.Althoughthereisaloopingridge,noridgecountcanbeobtained.Thecoreisplacedupontheendoftheridgeabuttingupontheinsideoftheloop,andsotheimaginarylinecrossesnoloopingridge,whichisnecessary.
[Fig.335]
Figure336isaplainarch.Theendingridgeatthecentercannotbeconsideredanupthrustbecauseitdoesnotdeviatefromthegeneraldirectionofflowoftheridgesoneitherside.Noangleispresentastheendingridgedoesnotabutuponthecurvingridgewhichenvelopesit.[Pg83]
[Fig.336]
Figure337isaplainarchbecausethedotcannotbeconsideredadeltaasitisnotasthickandheavyasthesurroundingridges.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 72/143
[Fig.337]
Figure338isatentedarchconsistingoftwoendingridgesandadelta.Theshortendingridgeisconsideredaridgebecauseitisslightlyelongatedandnotameredot.[Pg84]
[Fig.338]
Infigure339,theonlyquestioninvolvediswheretostoptracing.Theruleis:whentracingonaridgewithanupwardtrend,stopatthepointontheupwardtrendwhichisnearesttotherightdelta.Xisthepointinthispattern.
[Fig.339]
Infigure340,thequestioninvolvedisalsooneoftracing.Inthispattern,thetracingisnotonaridgewithanupwardtrend.Thetracing,therefore,iscontinueduntilapointnearesttotherightdelta,ortherightdeltaitself,isreached.Thistracingisameetingtracing.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 73/143
[Fig.340]
Thereareafewconstantlyrecurringpatternswhich,thoughnotquestionableordoubtfulastheyappear,presentapeculiarlydifficultprobleminclassifying.Thepatternsreferredtoareusuallydoubleloops,thoughaccidentalwhorlsandloopssometimespresentthesameproblems.Thedifficultyariseswhenaloopissoelongatedthattherecurvedoesnotappearuntilneartheedgeofafullyrolledimpressionoranimpressionthatisrolledunusuallyfar,asinfigures341to344.
[Figs.341344]
Figure341,ifclassifiedasitappears,wouldbeanaccidentalwhorl.Figures342and343wouldbedoubleloops,andillustration344,aloop.Itwillbeobservedthattheseprintsarerolledmorefullythannormal.If,however,thenexttimetheprintsaretaken,theyarenotrolledquite[Pg85]sofar,thepatternswouldrequireaverydifferentclassification,andwouldshownoindicationofanyneedforreferencingtotheirtrueclassification.Theresultwouldbeafailuretoestablishanidentificationwiththeoriginalprints.Theonlywayinwhichsuchanerrormaybeavoidedistoclassifysuchimpressionsastheywouldappearifnotsofullyrolled,andtoconductareferencesearchintheclassificationwhichwouldbegiventothe
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 74/143
printswhenrolledtothefullestextent.Applyingthisrule,illustration341isatentedarch,referencedtoawhorl.Figures342and343areloops,referencedtowhorls.Figure344isaplainarch,referencedtoaloop.
Nosetrulecanpossiblybedevisedtoenableaclassifiertoknowwithcertaintywheretodrawthelinewhenitisdoubtfulwhichclassificationshouldbegivensuchaprint.Individualjudgmentistheonlystandard.Thetestis:ifthepattern,intheopinionoftheclassifier,isrolledtoonlyanormalwidth,itshouldbeclassifiedasitappears.Ifitseemstoberolledtoawidthbeyondthenormaldegree,itshouldbeclassifiedasifrolledonlytothenormaldegree.Age,weight,sizeoffingers(asseenin[Pg86]theplainimpressions),heavinessoftheridges,andexperienceofthetechnicianintakingfingerprintsareallfactorsinarrivingatthecorrectconclusion.Thenecessityforexercisingtheutmostcareindealingwiththistypeofpatterncannotbetoohighlyemphasized.
Thepatternsinfigures345and346alsohaveasecondloopneartheedgeoftheimpression.Inthesetwopatterns,however,thesecondloopisverynearthedeltaandconsequentlywillalmostinvariablyappeareventhoughnotrolledtothefullestextent.Theforegoingruleisnotappliedtothistypeofimpression.Bothareclassifiedasawhorlandreferencedtoalooptotakecareoftherarecontingencyofnonappearance.
[Figs.345346]
[Pg87]
CHAPTERIV
TheClassificationFormulaandExtensions
Theclassificationformula
Atthispointitisnecessarytomentionthatwhenprintsareclassified,markingsareindicatedatthebottomofeachfingerblocktoreflectthetype.Thefollowingsymbolsareused:
Undertheindexfingerstheappropriatecapitallettersshouldbeplacedforeverypatternexcepttheulnarloop.
Underallotherfingers,theappropriatesmalllettershouldbeplacedforeverypatternexcepttheulnarloopandthewhorlasfollows:
Arch a
TentedArch t
RadialLoop r
Ulnarloopsinanyfingeraredesignatedbyadiagonallineslantinginthedirectionoftheloop.
Whorlsinanyfingeraredesignatedbytheletter"W".Theclassificationformulamaybecomposedofthefollowingdivisions:
1.Primary 4.Major
2.Secondary 5.Final
3.Subsecondary 6.Key
Thepositionsintheclassificationlineforthesedivisionswhencompletelyappliedareasillustrated:
Key Major Primary Secondary Subsecondary Final
Divisions Classification Classification Classification
20 M 1 U IOI 10
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 75/143
L 1 U IOI
Key Major Primary Secondary
SecondsubsecondaryclassificationSubsecondary Final
Divisions Classification Classification Classification
4 O 5 U
SLMMMSIOI 10
I 17 U IOI
Theprimaryclassification:Forthepurposeofobtainingtheprimaryclassification,numericalvaluesareassignedtoeachoftheten[Pg88]fingerspacesasshowninfigure347.Whereverawhorlappearsitassumesthevalueofthespaceinwhichitisfound.Spacesinwhichtypesofpatternsotherthanwhorlsarepresentaredisregardedincomputingtheprimary.
Thevaluesareassignedasfollows:
FingersNo.1andNo.2 16
FingersNo.3andNo.4 8
FingersNo.5andNo.6 4
FingersNo.7andNo.8 2
FingersNo.9andNo.10 1
[Fig.347]
[Enlarge]
Infigure347,itwillbeobservedthattheoddfingers(Nos.1,3,5,7,9)containtheletterD,andthe
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 76/143
evenfingers(Nos.2,4,6,8,10)containtheletterN.TheDindicatesthatthevaluesofthesefingersrelatetothedenominator,theNthattheyrelatetothenumerator.Thesummationofthenumericalvaluesofthewhorltypepatterns,ifany,appearinginfingers1,3,5,7,9,plusone,isthedenominatoroftheprimary.Thesummationofthevaluesofthewhorls,ifany,infingers2,4,6,8,10,plusone,isthenumeratoroftheprimary.Wherenowhorlappearsinasetofimpressions,theprimary,therefore,wouldbe1over1.The1thatis[Pg89]assignedtothenumeratorandthedenominatorwhennowhorlsappearisalsoadded,forconsistency,tothevalueofthewhorlswhentheydoappear.ItwillbeunderstoodwhyitwasoriginallyassignedtothenowhorlgroupwhenitisconsideredhoweasilyazeromightbeconfusedwithanO,whichisthesymbolusedforanouterwhorltracing.
Toobtaintheprimaryfortheprintsinfigure347,thenumberofwhorlsappearingintheoddfingersisascertainedtobe2.Theirpositionsarenoted(1inNo.1and1inNo.7)andthevaluesassignedtowhorlsappearinginthosefingersareaddedtogether(16plus2=18).Tothissumthearbitrary1isadded,givingusthetotalof19,whichconstitutesthedenominatorforthissetofprints.Togetthenumerator,itisascertainedthatthereare3whorlsappearingintheevenfingers(2,4and6),thevaluesofwhichareaddedtogether(16plus8plus4=28).Tothissumthe1isadded,givinganumeratorof29,andacompleteprimaryof29over19.
Bytheword"whorl"ismeantalltypesofwhorls,includingplainwhorls,centralpocketloops,doubleloopsandaccidentals.Thetracingofthewhorldoesnotenterintothedeterminationoftheprimary.
Themethodofobtainingtheprimarycanprobablybeshownbestbyillustrations.Forexample,assumethatthereisawhorlintherightindexfingeronly.Thevalueofawhorlinthisfingeris16.When1over1isaddedtheresultingprimaryis17over1.Ifawhorlappearsintherightthumbandrightindexfinger,thevalueis16over16plus1over1givingaprimaryof17over17.Ifwhorlsappearinbothindexfingers,thevalueis16over2plus1over1givingaprimaryof17over3.Whenwhorlsappearinboththumbsandbothindexfingers,theprimaryis21over19andisobtainedbytheaddition16plus4plus1over16plus2plus1.Ifwhorlsappearinall10fingers,theprimaryis32over32(16plus8plus4plus2plus1plus1over16plus8plus4plus2plus1plus1).Itwillbenotedthattheprimaryclassificationsextendfrom1over1inthenowhorlgroupto32over32intheallwhorlgroup,providing1,024possiblecombinations.Thisdoesnotmeanthatthereare1,024evensubdivisionsofprintsaccordingtotheseprimaries.Justasthereisapreponderanceofloopswhenthetypesofpatternsareconsidered,thereisalsoapreponderanceofcertainprimaries,notably:the1over1primary,ornowhorlgroupthe17denominatorthe19denominatorthe28denominator,ofwhichthe31over28groupisthelargestandthe32denominator,including2largeprimarygroupsnamely,31over32and32over32.Asamatteroffact,the1over1group,asawhole,containsover25percentofthetotalnumberofprintsfiledintheFBI.Ontheotherhand,thereareanumberofprimarieswhichrarelyappear.Itfollows,therefore,thatwhenaprintisclassifiedinoneoftheselargergroupsitisnecessarytocompletetheclassificationtoagreaterextentthanisnecessaryinthemoreunusualprimaries,sothatthegrouptobesearchedissmallenoughforconvenience.[Pg90]
Inconnectionwiththecountingofwhorlvaluestoobtaintheprimary,itmightbenotedthatwhenthewhorlsoutnumbertheotherpatternsmorespeedcanbeachievedbycountingthosepatternsandsubtractingratherthanbyaddingthewhorls.Thisprocedureshouldnotbefolloweduntilenoughexperienceisacquiredsothatitmaybenotedataglancewherewhorlsarenotpresent.
Theexperiencedclassifiercantellinwhatfingerswhorlsarepresentbyaglanceataprimaryclassification.Forexample,aprimaryof5over17couldmeanthattherearewhorlsinthethumbsonly.
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 77/143
[Fig.348]
[Enlarge]
Thesecondaryclassification:Aftertheprimaryclassification,thefingerprintsaresubdividedfurtherbyusingasecondaryclassification.Beforegoingintodetail,itshouldbenotedthataftertheprimaryisobtainedtheentireremainingportionoftheclassificationformulaisbaseduponthearrangementoftheimpressionsappearingintherighthandasthenumeratorovertheimpressionsappearinginthelefthandasthedenominator.Thearrangementoftheevenovertheunevenfingersisdiscardedaftertheprimaryisobtained.Thesecondaryclassificationappearsjusttotherightofthefractionalnumeralswhichrepresenttheprimary.Itisshownintheformulabycapitallettersrepresentingthebasictypesofpatternsappearingintheindexfingersofeachhand,that[Pg91]oftherighthandbeingthenumeratorandthatofthelefthandbeingthedenominator(fig.348).Therearefivebasictypesofpatternswhichcanappear.
1.Arch A
2.TentedArch T
3.RadialLoop R
4.UlnarLoop U
5.Whorl W
23/6/2015 TheScienceofFingerprints
http://www.crimesceneinvestigator.net/fbiscienceoffingerprints.html 78/143
[Fig.349]
[Enlarge]
Secondaryclassification(smalllettergroup):Printswithanarchortentedarchinanyfingeroraradialloopinanyexcepttheindexfingersconstitutethesmalllettergroupofthesecondaryclassification.Such"smallletters,"withtheexceptionofthoseappearingintheindexfingers,arebroughtupintotheclassificationformulaintheirproperrelativepositionsimmediatelyadjacenttotheindexfingers(fig.349).Adashisusedtoindicatetheabsenceofeachsmallletterbetweentheindexfingersandanothersmallletterorbetweentwosmallletters,as
1aUatand
1aUt.
1Ra1 1Ua
Thus,ifaradialloopappearsintherightthumb,[Pg92]thesmallletter"r"wouldbebroughtupinthenumeratorcolumnoftheclassificationformulaandplacedjusttotheleftofthecapitalletterrepresentingtheindexfinger.Similarly,ifanarchortentedarchoraradialloopwouldappearinthemiddle,ring,orlittlefingerofthehand,thesmallletterrepresentingsuchapatternwouldbeplacedontheclassificationlinetotherightofthesecondaryinthenumeratorcolumniftheletterispresentintherighthand,andinthedenominatorcolumnifinthelefthand.Whentwoormoresmalllettersofthesametypeoccurimmediatelyadjacenttoeachother,theyareindicatedthus:
1rU2aand
1aTaa.
1tU3a 1tA2at
Thesmalllettergroupsareofvitalimportancetotheclassificationsystem,astheyareofrelativelyinfrequentoccurrence,constitutingapproximately7to10percentofallpatterns.Generallyspeaking,sincethesepatternsareofsuchrareoccurrence,theirverypresenceoftenenablestheclassifiertodispensewiththeusualsubsecondaryclassificationandthemajordivisionwhichinthemajorityofcasesareusedinthelargergroups.
Thesubsecondaryclassification(groupingofloopsandwhorls):Inclassifyingprintsitisnecessarytosubdividethesecondarygroups.Thisisaccomplishedbygroupingaccordingtotheridgecountsofloopsandtheridgetracingsofwhorls.Thefirstofthegroupsfiledinorder,whichitwillbenecessarytososubdivide,wouldordinarilybethe
1R
1R
g