UNIT 4: FINGERPRINTS

Mr. ChapmanForensics 30

WHAT WILL WE LEARN & BE ABLE TO DO? 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.

HISTORICAL DEVELOPMENT OF FINGERPRINTS

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.

HISTORICAL DEVELOPMENT OF FINGERPRINTS

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.

HISTORICAL DEVELOPMENT OF FINGERPRINTS

In Western culture, the earliest record of the study of the patterns on human hands comes from 1684.

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.

ALPHONSE BERTILLON (1853 – 1914) 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...

WHAT ARE FINGERPRINTS?

FINGERPRINTS 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.

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

CHARACTERISTICS OF FINGERPRINTS Fingerprint characteristics are named

for their general visual appearance and patterns.

These patterns are called loops, whorls and arches.

Loops Whorls Arches65% 30% 5%

Percentage of Population With Specific Patterns:

• 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...

WHAT ARE YOUR FINGERPRINT TYPES?