Background



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Fingerprint Notes

Background
Chinese used fingerprints to sign documents 3,000 years ago.
Anthropometry

A system of identification by Alfonse Bertillon where individual body parts are

measured.
Bertillon's system of anthropometry was the 1st criminal identification method.
It was used for 20 years, but the Will West situation proved it to be inaccurate.
Most common method of identification from 1833 - 1903

Major Contributors to Fingerprinting


Henry Fauld (1880)

He said that skin ridge patterns could be important for the identification of criminals. He was ignored.
Francis Galton (1892)

Published Fingerprints (1st book on the topic)

3 Patterns of fingerprints: loops, arches, whorls

Edward Henry (1897) The Henry System


Developed the classification system of rations (Henry System) used today.
The 3 Principles of Fingerprints
1. A fingerprint is an individual characteristic.

2. Fingerprints remain unchanged during a lifetime.

3. Fingerprints have ridge patterns that can be classified.
1. A fingerprint is an individual characteristic

No two people (even identical twins) will have the same fingerprints.

Fingerprints are created in the womb (around 4 months fetal development)

They develop with the structure of human skin.

Dermal Papillae determines the form and pattern of fingerprints

Mathematically, the probability for the existence of two identical fingerprint patterns in the worlds' population is extremely small. Besides theoretical claculations, of the millions upon millions of individuals who have had their prints classified, no two fingerprints have been found to be identical.



2. Fingerprints remain unchanged during a lifetime

Fingerprints develop in the fetus and never change except to grow with the

growth of the body.

John Dillinger


John Dillinger, a famous outlaw, once tried to change his prints by using a corrosive acid. After he was shot to death, his prints matched earlier ones on file. This helps prove that prints cannot be changed.
Scarring - deep cuts will permanently damage fingerprint patterns

Minor injuries (burns, abrasions, or cuts) will not change the original fingerprint pattern as the original pattern is duplicated when new skin grows in.


3. Fingerprints have ridge patterns that are classified by:
No two prints have identical ridge characteristics. The friction ridges present on

the surface of the fingers are what gives us gripping ability (similar to treads on car tires).


The individuality of a fingerprint is not determined by its general shape or pattern, but by the careful study of its ridge characteristics, known as minutiae.
Ridge Minutiae
Fingerprints have various kinds of ridge characteristics (minutiae):

Bifurcations - a friction ridge that has split into two

Ridge Endings - point where a friction ridge ends.
It is the identity, number, and relative location of these minutiae that imparts individuality to a fingerprint. There are as many as 150 minutiae on the average

finger.
In judicial proceedings, an expert must demonstrate a point-by-point comparison in order to prove the identity of an individual. In court, it is customary to show at least a 12 point match.


The layer of skin responsible for the ridges is the Dermal Papillae.


Fingerprint Patterns

All fingerprints are divided into three classes on the basis of their general pattern: (L.A.W.)


Fingerprints have ridge patterns that are classified as:

goodgood

1. Loops - most common (60-65%)


2. Arch - least common (5%)
3. Whorl (30-35%)
Types of Ridge Patterns

LOOPS


Ridge pattern that enter and exit on the same side of the finger

Have ONE delta present


Delta - point where two lines intersect making a triangular shape
Types of Loops

Ulnar loop - loop that opens toward the little finger

Radial loop - loop that opens toward the thumb
ARCHES

Ridge pattern that enter on one side of the finger and exit on the other side.

NO DELTAS present
Types of Arches

Plain Arch - ridge rises in the center in a wave-like pattern

Tented Arch - rises and falls sharply
WHORL-

Ridge patterns that are somewhat circular in nature.

Contain TWO deltas
Types of Whorls

Both the plain whorl and a central pocket loop whorl have at least one ridge that makes a complete circuit.


Central Pocket Whorl - circuit may have an irregular shape

Double Loop Whorl - made up of two loops combined into one fingerprint



Accidental Whorl - contains two or more patterns or is a pattern not covered by the other categories.


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