What you Need to Know
(but may already know)
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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
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He classified fingerprints into 8 types based on
4 shapes
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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.
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Fingerprints are either visible or latent
Visible prints show up by themselves
Dirt, soot, blood, ink etc.
 Easy to spot
 Easily photographed
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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)
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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?
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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