Fingerprinting

FUNDAMENTAL PRINCIPLES OF FINGERPRINTS

First Principle:• A fingerprint is an individual characteristic. No two fingers have identical ridge characteristics.

Second Principle:• A fingerprint will remain unchanged during an individual’s lifetime.

Third Principle:• Fingerprints have general ridge patterns which make it possible to systematically classify.

A fingerprint consists of sweat, oil and amino acids.

All fingerprints are divided into three classes on the basis of

their general patterns.

Arches

Arches are the least common of the three general patterns and are subdivided into two distinct groups, Plain and Tented.

Plain Arches• The Plain Arch is the simplest of all fingerprint patterns

and is formed by ridges entering from one side of the print and exiting on the opposite side.

• These ridges tend to rise in the center of the pattern, forming a wave-like pattern.

Tented Arches

• The Tented Arch is similar to the Plain Arch except that instead of rising smoothly at the center, there is sharp upthrust or spike, or the ridges meet at an angle less than 90 degrees.

Loops

• The most common general pattern.

• A Loop is a type of pattern in which one or more ridges enter either side,recurve, touch or pass an imaginary line between Delta and Core, and tend to exit the same side as the ridge entry.

Deltas and Cores• The Delta is the first point on the first

characteristic. Deltas can also be any point upon a ridge nearest the center. They are located between two diverging Type Lines and are located on or directly in front of their point of divergence. Forms a triangular shape.

• Cores, as the name implies, are located in the approximate center of the pattern.

• Cores are located where the innermost recurve begins and curve to exit the same way they came in.

Whorls• The second most common of the three

general patterns are Whorls.

• Whorls are subdivided into 4 distinct groups: Accidental, Double Loop, Central

Pocket Loop and Plain.

Plain Whorls• Plain Whorls are the most common and simplest of the

Whorl subtypes.

• It is important to remember that Plain Whorls have two Deltas and at least one recurving ridge in front of each. In a Whorl pattern, the ridges are usually circular.

Central Pocket Loop Whorl• A Central Pocket pattern must have type lines, a

minimum of two Deltas and at least one ridge. The pattern tends to make a complete circle.

• An imaginary line can be drawn between the two Deltas and does not cross or touch a ridge inside the type lines. One Delta appears to be substantially closer to the center of the pattern than the other Delta.

Double Loop Whorls• A Double Loop pattern, as the name implies, is made up

of two Loops combined into one fingerprint.

• A Double Loop pattern consists of two separate Loop formations with two separate and distinct sets of Shoulders and two Deltas.

Accidental Whorls• Accidental Whorls consist of a combination of two different types of

patterns (with the exception of Plain Arches).

• Accidental Whorls may occur in some of the combinations listed below:• Loop and a Whorl• Loop and a Tented Arch• Loop and Central Pocket Loop• Double Loop and Central Pocket Loop

Unique Characteristics• The general pattern does not make a

fingerprint unique.

• Uniqueness results from the combination and location of the other characteristics.

• It is these characteristics that AFIS (Automated Fingerprint Identification System) uses to find a match

Unique Characteristics