Everything you wanted to know and more! FINGERPRINTING Everything you wanted to know and more!

A BIT OF HISTORY 3,000 years ago the Chinese used fingerprints to sign legal documents. 1883 Alphonse Bertillon developed a system of body measurements to identify individuals instead of fingerprints…this was used for 20 years.

The Will West Case A man named Will West was arrested. His measurements were taken for identification, then he was told that he was already an inmate at the prison under the name William West.

The Mug Shots: One is Will West, the other is William West They claimed they weren’t related.

The Fingerprints (West Case): Their fingerprints were very different.

So What’s the Deal with the West Case? It was later determined that Will West and William West were identical twins.

Three Fundamental Principles Fingerprints…. Are an individual characteristic- no two have been found that are exactly identical. Remain unchanged during a person’s lifetime. Have general characteristics that allow for classification.

Individual Characteristics Ridge Patterns (aka minutae)- their number, identity, and relative location are unique to each person Experts make at least 12 points of comparison between prints to prove a match.

Digital Print Comparison

Prints Remain Unchanged Fingerprints are formed by the papillae, a layer of tissue found between the epidermis (outer layer of skin) and the dermis (inner layer of skin). Papillae (wavy black line)

Fingerprint Classification There are three basic categories LOOP WHORL ARCH

LOOPS 60-65% have loops Lines enter one side, loop around, and exit the same side. One delta (triangular pattern)

WHORLS 30-35% Have whorls Rounded or circular pattern Two Deltas

ARCHES 5% Have arches Lines enter from one side and exit the other. NO Deltas

A FEW FINGERPRINT RIDGE CHARACTERISTICS ISLAND RIDGE ENDING ENCLOSURE BIFURCATION

Prints At The Crime Scene Visible Prints - made by a finger stained with blood, food, paint, ink, etc. Plastic Prints - Prints pressed into a soft surface like clay, soap, or wax Latent Prints - Invisible prints left by body oils and greases

LOCATING LATENT PRINTS For hard nonporous surfaces, such as glass, plastic, mirrors, tile, and painted wood- use dusting powder or Superglue fuming For soft, porous surfaces such as paper, cardboard and cloth- use Iodine fuming or other chemicals

Methods for Locating Latent Prints Dusting for Prints Chemical Processing

PRESERVING THE PRINT FOR EVIDENCE Always photograph the visualized latent print before further analysis for future comparison and evidence.

LIFTING A DUSTED PRINT After dusting and photographing the print, a piece of tape (like Scotch tape) is placed over it. The pattern of the dusted print is transferred to the tape which is then mounted on a piece of contrasting colored cardboard.

Printing methods we will use in class Inking and classifying prints Dusting with powder & lifting Superglue Fuming Iodine Fuming