What 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 aroun ID: 478445
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Slide1
Fingerprints
What you Need to Know
(but may already know)Slide2
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 worldSlide3
The Henry System
He classified fingerprints into 8 types based on 4 shapesSlide4
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.Slide5
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)Slide6
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?Slide7
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