Pikes Peak Writers Conference 2 - Fingerprinting

What I'm reading: Free Fire, by C.J. Box; The Immortal Life of Henrietta Lacks, by Rebecca Skloot (book club)

Continuing with workshop recaps from the Pikes Peak Writers Conference.

There were two workshops on forensics, both given by retired forensics expert, Tom Adair. (And, he's going to be my guest on May 8th). Both were "hands on" which made a great change from sitting and taking notes.

The first was about fingerprinting. (And although the workshop was hands on, he did begin with some facts.)

Fingerprints are unique and permanent (with very few exceptions, such as burns. They're established in the second trimester, pre-birth. In addition to fingerprints, all dermal ridge prints are unique to the individual (feet, toes, palms, etc.)

Contrary to what we might believe from television, prints are NOT everywhere. And, not finding someone's prints on an object doesn't mean the person didn't touch it. Finger marks are more common, but they're not usable for identification. Probably fewer than 10% of fingerprints found at a crime scene are identifiable to someone. It's not likely you'll get prints from bullet casings.











And speaking of identification—when prints are sent through the computer system, the results are NOT the names of their owners, complete with pretty pictures. They get back a list of "likely matches" and they're numbered. Eliminates any bias on the part of the examiner who might have a suspect in mind.

The quality of fingerprints is affected by environment. Here in Colorado, it's a very dry climate, and since fingerprints are mostly water, we don't leave as many as we would in a more humid environment. Also, as people age, their skin tends to dry out and become more brittle, so again, the quality of prints deteriorates. On the flip side, prints of prepubescent children don't last long on surfaces.

Most law enforcement officers are trained to lift prints using black powder, but the more sophisticated tests are done back in the lab.


Once Tom filled us in on background information, he turned us loose on his collection of things to print, and tools for printing. We had access to black fingerprint powder, magnetic powder, powders that fluoresced, and a collection of things he'd fumed with super glue. We discovered relatively quickly that he wasn't kidding. It wasn't easy for us to find prints, even when we were the ones making them and knew exactly where they were. To get my prints on a plastic fast-food cup, I first made sure I touched my fingers to my face (to pick up extra oils), and then planted them firmly on the cup. After that, Tom lifted them using tape and put them on a card.

The other important piece of takeaway information was that law enforcement is always looking to create a triangle, connecting the victim, the suspect, and the crime scene.

The second workshop was about forensics in 1875. Quite a difference. I'll have my recap of that one another time.

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