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 print 1. 2. 3. 4. 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! 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. Continue this process to make a fingerprint of all ten fingers on the “My Prints” worksheet. 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.