Vermont Forensic Vermont Forensic LaboratoryLaboratory

Physical Comparison UnitPhysical Comparison Unit

William William AppelAppelJennifer HannafordJennifer Hannaford

Al HogueAl HogueRachel Rachel LemeryLemery

27 February 200427 February 2004

Locard’sLocard’s Exchange PrincipleExchange Principle

“It was “It was Locard’sLocard’s belief that when a belief that when a criminal came into contact with an criminal came into contact with an object or person, a crossobject or person, a cross--transfer of transfer of evidence occurs.”evidence occurs.”

-- Richard SafersteinRichard Saferstein11

Locard’sLocard’s Exchange PrincipleExchange Principle

“Wherever he steps, whatever he touches, whatever he “Wherever he steps, whatever he touches, whatever he leaves leaves ---- even unconsciouslyeven unconsciously---- will serve as silent will serve as silent evidence against him. Not only his fingerprints or his evidence against him. Not only his fingerprints or his shoeprints, but also his hair, the fibers from his clothes, shoeprints, but also his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen that he deposits or scratches, the blood or semen that he deposits or collects collects ---- all these and more bear mute witness against all these and more bear mute witness against him. This is evidence that does not forget. It is not him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not confused by the excitement of the moment. It is not absent because human witnesses are. absent because human witnesses are. It is factual It is factual evidenceevidence. Physical evidence cannot be wrong; it cannot . Physical evidence cannot be wrong; it cannot perjure itself; it cannot wholly be absent. Only in its perjure itself; it cannot wholly be absent. Only in its interpretation can their be error. Only human failure to interpretation can their be error. Only human failure to find, study, and understand it can diminish its value.”find, study, and understand it can diminish its value.”

-- Paul L. KirkPaul L. Kirk44

What is Forensic Science?What is Forensic Science?Forensic Science is the application of science to law.Forensic Science is the application of science to law.

“Forensic science is the application of science to those “Forensic science is the application of science to those criminal and civil laws that are enforced by police criminal and civil laws that are enforced by police agencies in a criminal justice system”agencies in a criminal justice system”11

““CriminalisticsCriminalistics is concerned with the recognition, is concerned with the recognition, identification, individualization and evaluation of physical identification, individualization and evaluation of physical evidence using the methods of the natural sciences in evidence using the methods of the natural sciences in matters of legal significance”matters of legal significance”22

What is a Forensic Scientist?What is a Forensic Scientist?

“…one who performs investigatory examinations and “…one who performs investigatory examinations and laboratory tests to reach a conclusion”laboratory tests to reach a conclusion”33

Crime Scene InvestigationCrime Scene InvestigationLab AnalysisLab Analysis

“…a communicator and interpreter of those finding… “…a communicator and interpreter of those finding… he must be able to explain the methods used to reach he must be able to explain the methods used to reach those conclusion in a court of law...”those conclusion in a court of law...”33

Report Results (oral and/or written)Report Results (oral and/or written)Court TestimonyCourt Testimony

What is considered evidence?What is considered evidence?

Bite MarksBite MarksBlood and Body FluidsBlood and Body FluidsBonesBonesBroken Fingernails Broken Fingernails (striations)(striations)DrugsDrugsExplosivesExplosivesFiberFiberFingerprintsFingerprintsFirearm Powder ResiduesFirearm Powder ResiduesFirearms and Tool MarksFirearms and Tool Marks

GlassHairInkPaintPetroleum ProductsQuestioned Documents Shoeprints and Tire Tracks Soil and mineralsTeethToxicology

What is NOT forensic What is NOT forensic evidence?evidence?

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The value of evidenceThe value of evidence

Class CharacteristicsClass CharacteristicsProperties of evidence that can be only associated with a Properties of evidence that can be only associated with a group and never with a single sourcegroup and never with a single source

Individual CharacteristicsIndividual CharacteristicsProperties of evidence that can be attributed to a common Properties of evidence that can be attributed to a common source within an extremely high degree of certaintysource within an extremely high degree of certainty

Physical Comparison UnitPhysical Comparison Unit

Latent Print ProcessingLatent Print ProcessingFingerprint ComparisonsFingerprint ComparisonsIndented WritingIndented WritingFirearms/Firearms/ToolmarksToolmarksShoewearShoewear and Tire Tread Impressionsand Tire Tread ImpressionsPhysical MatchPhysical MatchForensic PhotographyForensic Photography

FingerprintsFingerprints

What is a Fingerprint?What is a Fingerprint?

Friction skin located on the fingers of the palm Friction skin located on the fingers of the palm side of the hand from the first joint to the nail side of the hand from the first joint to the nail bedbed

Areas of skin bearing ridges and furrowsAreas of skin bearing ridges and furrowsCorrugated skin on the Corrugated skin on the volarvolar areas of the skinareas of the skin

Specialized for tractionSpecialized for traction

Other types of friction skin…Other types of friction skin…

Palm

Fingers – area between first joint and the palm

Feet – soles of feet

Toes

LoopsLoopsOne or more ridges entering from one side of the print, One or more ridges entering from one side of the print, recurvingrecurving, and , and exiting from the same sideexiting from the same side

UlnarUlnar –– opens towards the little fingeropens towards the little fingerRadial Radial –– opens towards the thumbopens towards the thumb

Left Slant Right Slant

WhorlsWhorlsEnters from both sides and ridge flow that is circular in natureEnters from both sides and ridge flow that is circular in nature

Divided into four distinct groupsDivided into four distinct groups

ArchesArchesRidges that enter on one side and flow or tend to flow out the oRidges that enter on one side and flow or tend to flow out the other ther with a rise in the centerwith a rise in the center

Divided into two distinct groupsDivided into two distinct groups

Fingerprint Individual CharacteristicsFingerprint Individual Characteristics

Details within the ridge flow that represent a unique Details within the ridge flow that represent a unique occurrence occurrence (type, relative location, orientation and number)(type, relative location, orientation and number)

Ending ridgeEnding ridgeBifurcationBifurcationDotDot

Also known asAlso known asGaltonGalton DetailsDetailsMinutiaeMinutiaePoints of ComparisonPoints of Comparison

Random genetic expressionRandom genetic expression

Ending RidgeEnding RidgeA ridge that follows a distinct path and ends abruptlyA ridge that follows a distinct path and ends abruptly

BifurcationBifurcationRidge that follows a distinct path and divides into two ridgesRidge that follows a distinct path and divides into two ridges

DotDotA ridge unit that is as long as it is wideA ridge unit that is as long as it is wide

Scientific BasisScientific Basis

Fingerprints can be used for individualization Fingerprints can be used for individualization because they are because they are

UniqueUniquePermanentPermanent

UniquenessUniqueness

No two individuals or two fingers from the No two individuals or two fingers from the same hand share the exact friction ridge same hand share the exact friction ridge detaildetail

In over 100 years of billions of friction ridge In over 100 years of billions of friction ridge comparisons, no one has yet to find two areas of comparisons, no one has yet to find two areas of friction skin from different sources with the same friction skin from different sources with the same ridge configurationridge configuration

Identical twins Identical twins Same genetic makeSame genetic make--upupHow would this manifest itself in fingerprints?How would this manifest itself in fingerprints?

PermanencePermanence

During fetal development, friction ridges are During fetal development, friction ridges are formed and are permanent throughout life formed and are permanent throughout life until death and decompositionuntil death and decomposition

Except in instances of permanent scarring or Except in instances of permanent scarring or amputationamputation

Are these unique characteristics?Are these unique characteristics?

Latent PrintsLatent Prints

Generic term used to describe Generic term used to describe ANYANY evidentiary print evidentiary print recovered from a crime scenerecovered from a crime scene

The The unintentionalunintentional recording of friction ridge skinrecording of friction ridge skin

A reproduction of the friction ridge skin information A reproduction of the friction ridge skin information left on an object when touchedleft on an object when touched

The transfer of material from a surface to the The transfer of material from a surface to the friction ridge skin friction ridge skin

Evidentiary PrintsEvidentiary Prints

Latent / InvisibleLatent / InvisibleRidge impressions caused by the transfer of body Ridge impressions caused by the transfer of body perspiration or oils to the surface of an object perspiration or oils to the surface of an object requiring development or enhancement for their requiring development or enhancement for their visualizationvisualization

Patent / VisiblePatent / VisibleRidge detail transferred to a surface after the Ridge detail transferred to a surface after the ridges have been in contact with a colored ridges have been in contact with a colored material such as blood, paint, grease, or inkmaterial such as blood, paint, grease, or ink

Plastic / ImpressionPlastic / ImpressionRidge impressions left on a soft material such as Ridge impressions left on a soft material such as putty, wax, soap or dustputty, wax, soap or dust

Exemplar PrintsExemplar Prints

The The intentionalintentional recording of friction ridge skin recording of friction ridge skin from a known individual in a controlled from a known individual in a controlled environment for documentation, environment for documentation, classification, or comparisonclassification, or comparison

Form of collectionForm of collectionTen print cardTen print cardMajor case recordsMajor case recordsPostPost--mortem printsmortem prints

Examples of collectionArrestMilitary recordJob requirementSubpoenaDriver’s licenseBirth

Friction Ridge ComparisonFriction Ridge Comparison

Identifications are affected by viewing Identifications are affected by viewing these ridge characteristics taking into these ridge characteristics taking into consideration their similarity, their consideration their similarity, their number and their unit relationship to number and their unit relationship to each othereach other

NO UNEXPLAINABLE DIFFERENCESNO UNEXPLAINABLE DIFFERENCES

Recording ExemplarsRecording Exemplars

Recording ExemplarsRecording Exemplars

Indented WritingIndented Writing

Obliterated WritingObliterated Writing

OriginalOriginal Viewing with IR FilterViewing with IR Filter

Firearms and Firearms and ToolmarksToolmarks

FirearmsFirearms

Firearms ExaminationsFirearms Examinations

Fired BulletsFired Bulletsgeneral characteristics such as calibergeneral characteristics such as caliberphysical features of rifling impressionsphysical features of rifling impressionsmanufacturer of bulletsmanufacturer of bullets

Cartridge Cases or Cartridge Cases or ShotshellShotshell CasingsCasingscaliber or gaugecaliber or gaugemanufacturermanufacturerpresence of marks for comparisonpresence of marks for comparison

Shot Pellets, Buckshot, SlugsShot Pellets, Buckshot, Slugssize of shotsize of shotgauge of sluggauge of slugmanufacturermanufacturer

WaddingWaddingcomponents can determine gauge and manufacturercomponents can determine gauge and manufacturer

FirearmsFirearms

Firearms Examinations, cont.Firearms Examinations, cont.

Gunshot ResidueGunshot Residueindication of holding/firing weaponindication of holding/firing weaponchemical componentschemical components

Shot PatternShot Patterntype of guntype of gundistance from muzzledistance from muzzle

Bullet and CasingBullet and Casingmatched back to gun (ejector, firing pin, breechblock, and extramatched back to gun (ejector, firing pin, breechblock, and extractor marks)ctor marks)matched back to same lot of ammunition found in suspect's possesmatched back to same lot of ammunition found in suspect's possessionsion

FirearmsFirearms

A bullet is impressed A bullet is impressed with the rifling with the rifling markings of the barrel markings of the barrel when it emerges from when it emerges from the weapon.the weapon.

Firearms ExaminationFirearms Examination

Photomicrograph of two bullets through a Photomicrograph of two bullets through a comparison microscope. The test bullet is on comparison microscope. The test bullet is on the right; the questioned bullet is on the left.the right; the questioned bullet is on the left.

Physical MatchingPhysical Matching

Crime Scene SearchCrime Scene Search

History of Forensic ScienceHistory of Forensic Science

Forensic Science TimelineForensic Science TimelineNorah Norah RudinRudin

www.forensicdna.com/Timeline.htmwww.forensicdna.com/Timeline.htm

ReferencesReferences11 SafersteinSaferstein, R., , R., CriminalisticsCriminalistics An Introduction to Forensic An Introduction to Forensic Science, Science, 44thth ed., Englewood Cliffs, N.J.: Prenticeed., Englewood Cliffs, N.J.: Prentice--Hall, Inc., Hall, Inc., 1990.1990.

22 DeForestDeForest, P.R., , P.R., GaensslenGaensslen, R.E., and Lee, H.C. , R.E., and Lee, H.C. Forensic Forensic Science An Introduction to Science An Introduction to CriminalisticsCriminalistics, , New York,New York, McGrawMcGraw--Hill, Inc. 1983.Hill, Inc. 1983.

33 KuzmackKuzmack, N.T.: “Legal Aspects of Forensic Science,” in R. , N.T.: “Legal Aspects of Forensic Science,” in R. SafersteinSaferstein (ed.), (ed.), Forensic Science Handbook, Forensic Science Handbook, Englewood Cliffs, Englewood Cliffs, N.J.: PrenticeN.J.: Prentice--Hall, Inc., 1982.Hall, Inc., 1982.

44 Kirk, P.L., Kirk, P.L., Crime Investigation, Crime Investigation, 22ndnd ed., New York: John Wiley ed., New York: John Wiley & Sons, Inc., 1974.& Sons, Inc., 1974.

55 ChisumChisum, W.J. and , W.J. and TurveyTurvey, B.: “Evidence Dynamics: , B.: “Evidence Dynamics: Locard’sLocard’sExchange Principle & Crime Reconstruction,” Exchange Principle & Crime Reconstruction,” Journal of Journal of Behavioral Profiling, Behavioral Profiling, January, 2000, Vol. 1, No. 1.January, 2000, Vol. 1, No. 1.