What you Need to Know (but may already know)

 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

 He classified fingerprints into 8 types based on 4 shapes

 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.

 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)

 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?

 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