Fingerprint Evidence

Solving the Mystery

When police come upon a crime scene, the first thing that they do is seal off the area and prevent anyone but experts to enter. They do this so that their own hair, fingerprints and clothing do not contaminate the evidence.

Contaminate: to change or alter in a negative way a crime scene can be contaminate by other people’s fingerprints.

Fingerprint Patterns

Fingerprints can be decided into three main patterns: loops, whorls, and arches.

A clear fingerprint is excellent evidence.

No two fingerprints in the world are alike.

A Fingerprint will remain unchanged during an individuals lifetime (unless scars appear)

Twins?

Types of Fingerprints

Deltas

Not a type of fingerprint, but it helps us to classify the finger prints. A delta is a triangular pattern on the finger print as shown in the picture below.

Arches

Arches are found in about 5% of fingerprint patterns encountered. The arch pattern of finger print is like a wave or a hill. The ridges enter on one side of the print, rise in the middle and exit on the opposite side of the print. The arch print has no delta.

Whorls

Whorls are seen in about 25-35 % of fingerprint patterns. In a whorl, some of the ridges make a turn through at least one circuit. Any fingerprint pattern which contains 2 or more deltas (triangle) will be a whorl pattern.

Loops

Loops are the most common fingerprint and is in 60-65% of the population. Must have one or more ridges entering from one side of the print, curving and exiting from the same side. It has one delta.

Composite

The composite pattern is a combination of patterns such as a whorl and arch, a loop and an arch, or a whorl and a loop

Unique Characteristics of

Finger Prints

Other Than The Type

When the police identify fingerprints, the first thing they do is look at the pattern of the print i.e., loop, whorl, arch or composite.

Once they have a matching pattern type, they look for unique features of a print to help them match a suspect to the fingerprints found at the scene of a crime

Ridge Characteristics

In order for the print to be considered "a match" they must have a number of ridge characteristics in common

Bifurcation (fork)

One ridge splits to form two ridges and then rejoin to one ridge again, forming a shape like a lake.

Ridge Endings

A ridge ends.

Islands

A very short ridge in the print pattern is not connected to any other ridge, much like an island floating by itself.

Lakes

A circle shape in the middle of a ridge

Deltas

Many fingerprints have unique delta’s that would also will qualify as a ridge characteristic

All together

Others