Fingerprints

“Fingerprints cannot lie, but liars can make fingerprints.” --- unknown

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What is a fingerprint?• An imprint made by ridge patterns on the tip

of a finger.• Also used to describe the characteristic

pattern of DNA fragments.

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Why are fingerprints useful?Properties that make a fingerprint useful for ID: It’s unique characteristic ridges which make them

individual evidence. It’s consistency over a person’s lifetime. It remains

unchanged during an individual’s lifetime.The systematic classification is used for fingertips

based on their general characteristic ridge patterns.

DactyloscopyThe Study of Fingerprints

History from 1850 to 1900

William Herschel—required Indians to put their fingerprints on contracts, and used fingerprints as a means of identifying prisoners

Henry Faulds—claimed that fingerprints did not change over time and that they could be classified for identification

Alphonse Bertillon—proposed body measurements as a means of identification; termed anthropometry

Francis Galton—developed a primary classification scheme based on loops, arches, and whorls

Edward Richard Henry—in collaboration with Galton, instituted a numerical classification system

Juan Vucetich—developed a fingerprint classification system based on Galton’s that is used in Spanish-speaking countries

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Recording and classifying prints Rolling inked prints

3 Basic patterns - Loops, whorls, arches

Ridge characteristics – Minutiae (very small)

Primary identification number

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Lifting prints

Black, white, and fluorescent powder

Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate

Other types of prints

Palm, lip, teeth, eye, ear, voice, shoeprints, and footprints

Collection and Classification of Prints

Ridge Characteristics

Minutiae—characteristics of ridge patterns

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Fingerprint Minutiae

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LOOP

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WHORL ARCH

Basic Fingerprint Patterns

LoopA loop must have one or more ridges

entering from one side, curving around and exiting from the same side. Loops must have one delta.

Most common type (65%) and more

common in people of European background. Also, forefingers have most of the radial loops.

Types

Radial—opens toward the thumb

Ulnar—opens toward the “pinky” (little finger)

Which type of loop is this, if it is on the right hand? Left hand?

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WhorlA plain or central pocket whorl has at least

one ridge that makes a complete circuit. A double loop is made of two loops. An accidental is a pattern not covered by other categories. Whorls have at least two deltas and a core.

Found in 30% of population. People of Asian ancestry are more likely to have whorls.

TypesPlain

Central pocket

Double loop

Accidental

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ArchAn arch has friction ridges that

enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores.

Least common type (5%) and more likely found in people of African ancestry.

Types

Plain – gradual bump

Tented – much higher, pinched arch

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Four Types of Whorls

Whorl: line drawn from delta to delta intersect circle.

Double Whorl

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Central Pocket: line drawn from delta to delta do not intersect circle.

Accidental: prints too irregular to fall into any group.

Primary Classification

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The Henry-FBI Classification System

Each finger is given a point value.

right leftRight Right Left Left Left index ring thumb middle little 16 8 4 2 1 + 1 =Right Right Right Left Leftthumb middle little index ring 16 8 4 2 1 + 1 =

Example: Whorl on your left thumb and right middle finger. 0 + 0 + 4 + 0 + 0 + 1 = 5 5 is your primary 0 + 8 + 0 + 0 + 0 + 1 = 9 9 classification

**Fingerprints are given as a fraction. Identify which fingers have whorls; each whorl has a number based on which finger it is on. Loops and arches are a “0”.

Comparison

There are no legal

requirements in the United

States on the number of

points required for a match.

Generally, criminal courts will

accept 8 to 12 points of

similarity.

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Identify each fingerprint pattern

Right Hand

Left Hand

Left Hand

Right Hand

Right Hand 21

It’s time to make

some prints!

Avoid Parti

al Print

s

GOOD PRINTGet as much of the

top part of your finger as possible!