Officer TenDigits* here,
Welcome students, mystery writers, and true crime authors.
Oh, and any others seeking info about fingerprint techniques.
Whatever your reasons to master this arcane subject, be sure to check out the other fingerprint tutorials in this series. Go here and here. Another similar tutorial’s coming soon.
In today’s class, ahem, I won’t be talking about any newly-created forensics methods requiring gold and zinc that local police jurisdictions can use. Unless you’ve got a lead on the Zodiac Killer or JFK’s Second Shooter, I doubt this whiz-bang Vacuum Metal Deposition method would be at a typical investigator’s disposal. Oops, the Zodiac’s just been ID’d. (Hope it’s definitive this time. So many false IDs over the years.)

Fingerprint
Fingerprint techniques.
Fingerprints, palm prints, and footprints are the most accepted form of physical identification. Tho it took a while, the unique characteristics of a print have been accepted by courts of all kinds in establishing identity.
This acceptance is based on a probability factor, as are all other forms of identity evidence. Studies haves shown
that the probability of two persons having exactly the same fingerprints is so minute as to be negligible.
Since palm and footprints are of similar value in terms of identification, my remarks will mostly focus on fingerprint techniques.

Multi prints.
Lifting prints from various surfaces.
An aside to readers before you accept all this as gospel and include it in your next crime novel. Realize that a rule of thumb taught many officers is that you do not know what prints you can lift until you’ve tried. Processing involves many techniques other than dust and brush!

Latent fingerprint/s
There is a wide range of chemicals used to visualize latent or hidden prints on various porous surfaces, or to make visible prints deposited by, say, blood transfer. One of the best tools around for screening prints is UV light direct, viewed through a low light viewing system maximized for UV spectrum.
It is extremely challenging to get prints from the following
– oily, rusty, or extremely dirty surfaces.
– high traffic surfaces with multiple overlapping prints, and
– prints smeared by movement.
However, we’ll be posting a blog soon about the amazing techniques and heroics involved in some contemporary lifting procedures.
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