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The Federal Bureau of Investigation (FBI) started to compile fingerprint
files in 1924. There are millions of fingerprints in the FBI fingerprint
files. Fingerprints are still sometimes made by rolling fingers in ink and
pressing them against paper. New techniques for making digital images
of fingerprints are being developed. FBI fingerprints are divided into
criminal and noncriminal files. Noncriminal prints include government
employees, teachers in some states, and people who have volunteered
their prints for identification purposes.
Latent prints are fingerprints we leave on certain surfaces. Latent prints
are used to connect criminals to their crimes. Criminals do not leave
prints at crime scenes on purpose. In fact, their fingerprints are usually
invisible. They’re made by oil or sweat on the skin ridges.
Footprints
Fingertips are not the only places on the skin
with ridges. Ridges also exist on your palms,
your toes, and the soles of your feet. These
ridges are also unique to you. They can be used
to identify you. That’s why hospitals take inked
prints of the soles of babies’ feet.
A police officer
looking at a
fingerprint on
a computer
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