Fingerprints YAP 2011

Ancient Fingerprinting  Chinese used fingerprints in seals by 264BCE  ~1300, Persian Rashid-al-Din Hamadani writes: "Experience shows that no two individuals have fingers exactly alike.”

Sir William Herschel: 1858  Showed that fingerprint patterns were permanent  Initiated fingerprinting in India as a form of signature verification

Sir Francis Galton: 1888  Wrote the book “Fingerprints”  Classified fingerprints into 8 categories  Calculated that the chances of identical fingerprints was 1:64B

Sir Edward Henry  Developed the Henry Classification System for faster manual searching  Still in use in many British commonwealth countries

AFIS/IAFIS  Automatically checks suspect fingerprints against database.  IAFIS contains over 81 million sets of criminal and civil fingerprints

Fingerprint Anatomy  Friction ridge skin Begins forming in utero at 4 mos. Begins forming in utero at 4 mos. Is Permanent and Unique Is Permanent and Unique  Different even between identical twins

Arches Arches 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 Arch Ridges 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”

Loops Loops 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.

Whorls Whorls 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 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

Ridge Characteristics Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

Ridge Characteristics Crossover Core Bifurcation (fork) Ridge ending Island Delta Pore Scar

How are fingerprints made?  Pressure from the ridges separate a substrate  Sweat, fats, and salts are exuded by pores in the ridge skin, and stick to a substrate

3 Types of Prints  Patent  Latent  Impression

Collecting Patent Prints  Printing in ink  Photographing  Lifting

Latent Prints  Invisible to the naked eye  Must be developed with chemicals or light  Porous, nonporous, and semi-porous substrates

Dusting  Powder adheres to fats & oils  Different colored powders for different substrates  Apply with fiberglass brush  Clean up with camel hair

ALS  Fluorescent dyes or powders  Lit with ultraviolet light  Photographed with filter lenses

Other Techniques  Sticky-side powder  Camphor fuming

Porous Substrates  Ninhydrin  Iodine

Lifting a Print 1. Diagram the site 2. Press the lifting tape across the print 3. Smooth the tape flat 4. Lift off the print 5. Press it over the lift card