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