Mr. Chapman Forensics 30

 By the end of this unit, you should be able to: 1. Describe the general characteristics of fingerprints, as well as their usefulness in criminal investigation, 2. Acquire and analyze latent fingerprints from surfaces, and match them to suspect fingerprints based on minutiae. 3. Identify common methods of criminal fingerprint disguise, as well as understand the relevance and future of fingerprint analysis.

 For thousands of years, humans have been fascinated by the patterns found on the skin of their fingers.  Just last week I mentioned fingerprints to you guys, and half of you couldn’t stop looking at your hands.  Maybe surprisingly, it took a long time before people realized that everyone’s fingerprints are unique.

 Archaeologists have discovered fingerprints pressed into clay tablet contracts as signatures, dating back as far as 1792 B.C.  On the right is a clay tablet that actually represented the sale of a field and a house.

 In Western culture, the earliest record of the study of the patterns on human hands comes from  Distinct fingerprint patterns were described in 1823, and in 1856, Sir William Herschel began the collecting of fingerprints.  Herschel recognized that fingerprints were unique to each person, and not altered by age.

 In 1879, an assistant clerk at a police station named Alphonse Bertillon created a way to identify criminals who were repeat offenders, based on fingerprints.  In 1902, he was credited with solving the first murder using fingerprints.  How did clerks solve murders?!

So then we have the question...

 Your hands, toes, feet and palms are not smooth, shiny surfaces. This turns out to be a good thing – if they were, you would have a hard time gripping things.  Instead, these surfaces are covered with small ridges that are raised portions of the skin.  When these ridges press against things, they leave a mark, and this mark is called a fingerprint.

Your fingerprints are formed around the 10 th week of pregnancy, when the fetus is about three inches long.

 Fingerprint characteristics are named for their general visual appearance and patterns.  These patterns are called loops, whorls and arches. LoopsWhorlsArches 65%30%5%

Arches are the least common of the 3 types of fingerprints. Approximately 5% of all fingerprints are arches – they are the least prevalent type. Arches have ridges that enter from one side of the fingerprint and leave from the other side with a rise in the center.

Whorl Fingerprints Whorls look like a bull’s-eye, with two deltas (triangles). Whorls are the distinguishing feature in approximately 30% of all fingerprints.

Loop Fingerprints Loops enter from either the right or the left and exit from the same side they enter. Loops are the most common of the fingerprints, appearing in approximately 65% of all fingerprints.

And now we need to find out...