I’m actually not talking about fingerprints, today. Although that’s an interesting, and somewhat fraught, topic in forensics, for one very good reason: there is no established minimum. You can, in theory, take a mere three or four points of reference matching an unknown print to a known, and call it identified. That would be silly, but sadly, there’s nothing to say you can’t do it. Yet. I hold out hope for a more rigorous standard in coming years as it is apparent forensic fingerprinting is not held to a high enough bar to cross for admissible evidence. No, what I’m talking about today is what makes up the fingerprints themselves.
Locard’s principle, that anything we come in contact with transfers a trace of itself to us, and we to it, has never been taken to such miniscule levels. We now have the technology to test a microscopic trace of an unknown person left at a crime scene, and it can reveal to us what sex they are, what they look like down to hair and eye color, their genetic identity, and now, even what drugs they may have in their system. Touch DNA is what can be extracted from the nuclei of skin cells left behind in fingerprints. We shed our dead cells constantly, and although tracking a single cell authoritatively to a perpetrator to say ‘so and so was here at this time’ is a nigh-impossible task, using the cells in a fingerprint allows forensic analysts to declare that the print, the DNA; they go together.
And now, four classes of illicit drugs can be detected from fingerprint sweat, as well. The current test is to allow for presumptive detection of cannabis, cocaine, opiates, and amphetamines from the finger of a living or dead body. But it doesn’t take much of a leap forward to extract that information from a fingerprint. For now, being able to quickly detect illicit drugs and then confirm with the more time-consuming methods that are more precise is enough to be an exciting new tool in analyst’s ability to aid in law enforcement. Also, given some time, I’m sure that other drugs and substances will be added to the test, as well.