FINGERPRINTSWhat you Need to Know (but may already know)

History

Sir Edward Henry (of London Metropolitan Police) developed modern system of identifying criminals by their fingerprints in 1900

The Henry system (as it is sometimes known) was so useful in criminal investigations that it was adopted around the world

The Henry System

He classified fingerprints into 8 types based on 4 shapes

Fingerprint Info

No two people have the same fingerprints Your fingerprints should stay the same

throughout your life. They change only because of accident, illness or surgery.

Prints are based on “hills” and “valleys” on your skin.

At the Scene

Fingerprints are either visible or latent Visible prints show up by themselves

Dirt, soot, blood, ink etc. Easy to spot Easily photographed

Latent prints are hidden Produced by perspiration Have to be made visible with powder and

lifted off surface using special tape (then photographed)

On fabric or paper latent prints are made visible with chemical dye (then photographed)

In the Lab

If fingerprints are found at the crime scene, the next step is to find out who they belong to

Victims can be fingerprinted to eliminate them Convicted criminals have fingerprints taken and

stored Computers can rapidly tell if prints found at a

crime scene match those of a known criminal AFIS (automated fingerprint identification

system) Who else may be fingerprinted?

Hmm. Interesting.

British detectives believed that 2 prints matched when 16 specific features of one print matched the features in the other

American detectives believed it was enough to match 8 or 12 features

Recently the number of matching features has become less relevant and balanced by whether there are any major differences between the 2 prints