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09/08/03
 The
story begins like an old gangster flick: a gang of criminals
and an unexpected kidnapping.
On a
warm summer evening in 1933, William A. Hamm, Jr., President
of the Theodore Hamm Brewing Company, was working at his office
in St. Paul, Minnesota. He had just exited the building when
he was grabbed by four shadowed figures and pushed into the
back of a car. What he didn't know was that he had been kidnapped
by members of the Barker/Karpis gang, for a ransom of over
$100,000.
Hamm
was taken to Wisconsin, where he was forced to sign four ransom
notes. Then he was moved to a hideout in Bensenville, Illinois,
were he was held prisoner until the kidnappers had been paid.
Once the money was handed over, Hamm was released near Wyoming,
Minnesota. The plan was perfect and went off without a hitch...almost.
Enter
the FBI Crime Lab. On September 6, 1933--almost precisely
70 years ago--and using a then state-of-the-art technology,
now called 'Latent Fingerprint Identification,' it raised
incriminating fingerprints from surfaces that couldn't be
dusted for prints. Alvin Karpis, "Doc" Barker, Charles
Fitzgerald, and the other members of the gang had gotten away,
but they'd left their fingerprints behind -- all over the
ransom notes.
A
Forensic First
It's
called the Silver Nitrate Method and its application in the
Hamm Kidnapping was the first time it was used successfully
to extract latent prints from forensic evidence. Scientists
had just thought to take advantage of the fact that unseen
fingerprints contain perspiration, chock full of sodium chloride
(common table salt). By painting the evidence, in this case
the ransom notes, with a silver nitrate solution, the salty
perspiration reacted chemically to form silver chloride --
which is white and visible to the naked eye. There they were:
hard evidence that the Karpis gang was behind the kidnapping.
Case closed.
Today
"latents" are developed by hugely sophisticated
methods. The FBI's Latent Print Unit uses powders, lasers,
and alternative light sources to detect and analyze partial
and complete fingerprints. Its Cyanoacrylate process encloses
evidence in a sealed cabinet and exposes it to cyanoacrylate
glue fumes in order to bring up prints. Fluorescent lights
and lens filters are also used to good effect. Then, once
the latent print has been found, it is run through the Bureau's
Integrated Automated Fingerprint Identification System (IAFIS)
-- an electronic network of databases of well over 8 million
fingerprints, housed in the FBI's Criminal Justice Information
Service Division in Clarksburg, West Virginia. When a match
is made, chances are good that it's the beginning of the end
of the investigation.
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