Upload
louisa-reynolds
View
213
Download
0
Tags:
Embed Size (px)
Citation preview
FingerprintsFingerprints
YAP 2011YAP 2011
Ancient FingerprintingAncient Fingerprinting
Chinese used fingerprints in seals by Chinese used fingerprints in seals by 264BCE264BCE
~1300, Persian Rashid-al-Din Hamadani ~1300, Persian Rashid-al-Din Hamadani writes: "Experience shows that no two writes: "Experience shows that no two individuals have fingers exactly alike.”individuals have fingers exactly alike.”
Sir William Herschel: 1858Sir William Herschel: 1858
Showed that fingerprint Showed that fingerprint patterns were patterns were permanentpermanent
Initiated fingerprinting in Initiated fingerprinting in India as a form of India as a form of signature verificationsignature verification
Sir Francis Galton: 1888Sir Francis Galton: 1888
Wrote the book Wrote the book “Fingerprints”“Fingerprints”
Classified fingerprints Classified fingerprints into 8 categoriesinto 8 categories
Calculated that the Calculated that the chances of identical chances of identical fingerprints was 1:64Bfingerprints was 1:64B
Sir Edward HenrySir Edward Henry
Developed the Henry Classification Developed the Henry Classification System for faster manual searchingSystem for faster manual searching
Still in use in many British commonwealth Still in use in many British commonwealth countriescountries
AFIS/IAFISAFIS/IAFIS
Automatically checks Automatically checks suspect fingerprints suspect fingerprints against database. against database.
IAFIS contains over IAFIS contains over 81 million sets of 81 million sets of criminal and civil criminal and civil fingerprintsfingerprints
Fingerprint AnatomyFingerprint Anatomy
Friction ridge skinFriction ridge skin Begins forming in utero Begins forming in utero
at 4 mos. at 4 mos. Is Permanent and Is Permanent and
UniqueUnique Different even between Different even between
identical twinsidentical twins
ArchesArchesArches are the simplest type of fingerprints that are formed by ridges that enter on one side of the print and exit on the other. No deltas are present.
Plain ArchRidges enter on one side and
exit on the other side.
Tented Arches Similar to the plain arch,
but has a spike in the center.
Spike or “tent”
LoopsLoopsLoops must have one delta and one or more ridges that enter and leave on the same side. These patterns are named for their positions related to the radius and ulna bones.
Delta
Ulnar Loop (Right Thumb)
Loop opens toward right or the ulna bone.
Radial Loop (Right Thumb)
Loop opens toward the left or the radial bone.
NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop.
WhorlsWhorlsWhorls have at least one ridge that makes (or tends to make) a complete circuit. They also have at least two deltas. If a print has more than two deltas, it is most likely an accidental.
Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl.
Plain Whorl
Central Pocket Whorl
Whorls – Part 2Whorls – Part 2
Accidental Whorl
Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories.
Double Loop Whorl
Double loop whorls are made up of any two loops combined into one print.
Delta
Delta
Rid
ge C
har
acte
rist
ics
Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!
http://cnx.org/content/m12574/latest/properties.jpg
Ridge Characteristics
Crossover
Core
Bifurcation (fork)
Ridge ending
Island
Delta
Pore
Scar
How are fingerprints made? How are fingerprints made?
Pressure from the ridges Pressure from the ridges separate a substrateseparate a substrate
Sweat, fats, and salts Sweat, fats, and salts are exuded by pores in are exuded by pores in the ridge skin, and stick the ridge skin, and stick to a substrateto a substrate
3 Types of Prints3 Types of Prints PatentPatent LatentLatent ImpressionImpression
Collecting Patent PrintsCollecting Patent Prints
Printing in inkPrinting in ink PhotographingPhotographing LiftingLifting
Latent PrintsLatent Prints
Invisible to the Invisible to the naked eyenaked eye
Must be developed Must be developed with chemicals or with chemicals or light light
Porous, nonporous, Porous, nonporous, and semi-porous and semi-porous substratessubstrates
DustingDusting
Powder adheres Powder adheres to fats & oilsto fats & oils
Different colored Different colored powders for powders for different different substratessubstrates
Apply with Apply with fiberglass brushfiberglass brush
Clean up with Clean up with camel haircamel hair
ALSALS
Fluorescent dyes Fluorescent dyes or powdersor powders
Lit with ultraviolet Lit with ultraviolet lightlight
Photographed with Photographed with filter lensesfilter lenses
Other Techniques Other Techniques
Sticky-side powderSticky-side powder Camphor fumingCamphor fuming
Porous SubstratesPorous Substrates
NinhydrinNinhydrin IodineIodine
Lifting a PrintLifting a Print
1.1. Diagram the siteDiagram the site2.2. Press the lifting Press the lifting
tape across the tape across the printprint
3.3. Smooth the tape Smooth the tape flatflat
4.4. Lift off the printLift off the print5.5. Press it over the Press it over the
lift cardlift card