Chapter 4 - Fingerprints

CHAPTER 4 - FINGERPRINTS

Chapter Objectives Why fingerprints are individual evidence.Define the three basic properties that allow

individual identification by fingerprints. Recognize the general ridge patterns (loops,

whorls, and arches). Explain the differences among latent, plastic,

and visible fingerprints. Develop latent prints (make them visible) using

physical and chemical methods.

Dactyloscopy -The Study of Fingerprints 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

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

Fundamental Principles of Fingerprints

A fingerprint is an individual characteristic.A fingerprint remains unchanged during an

individual’s lifetime.Fingerprints have general characteristic ridge

patterns that permit them to be systematically classified.

Fingerprint classes

Arch An 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.

Loop A loop must have

one or more ridges entering and exiting from the same side. Loops must have one delta.

Whorl A plain or central pocket

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

Whorls cont

Double Loop Whorl

Delta

Delta

Accidental Whorl

Fingerprint ridge characteristics

Fingerprint minutiae

Facts about fingerprints 60% of people have loops 35% have whorls, 5% have arches

How to make a print1. Roll the “pad” portion of your thumb over the ink pad from

the left side of your thumb to the right. You do not have to push down really hard!

2. Roll the “pad” portion of your thumb from the left side of your thumb to the right in the correct box on your paper to make a thumbprint.

3. Continue this process to make a fingerprint of all ten fingers on the “My Prints” worksheet.

4. Use your notes and a magnifying lens to help you figure out what type of pattern is found in each of your fingerprints. Label each one with the pattern’s name.