Fingerprints Reveal A Smoker, A Drinker, A Drug-Taker…And More!

Fingerprint's reveal a smoker


Imagine how difficult it is to solve a murder when all you have as evidence is a single fingerprint. And, that print is not in any database, anywhere.  Sure, there were eight men who were seen near the scene of the crime on the night it occurred, but you have nothing solid pointing you in their direction.

Man, if only that print could talk.

I guess, for starters, the print could tell the investigator what the suspect had been holding in his hand, recently. For example, a cigarette, or a bottle of beer. Or even a bag of cocaine. But would it help to know if the fingerprint belonged to a smoker? Well, during your surveillance of the suspects you’ve seen six of the eight puffing away at various times. So that’s not a lot of help. How about if the print belonged to a person who drank alcohol? During the course of your investigation you’ve learned that only four of the suspects consumed alcohol. And you verified that information with family and friends. What about a drug user? Would it help to know if the print belonged to a drug user? After all, one of your informants says the guy with the big ears and red hair smokes crack regularly. So you try to dig up similar information about the other seven. Nothing. They’re all clean. No drugs. Red-On-The-Head is the only one who uses drugs.

So, if you knew for sure that the print belonged to a drug user and one of your only seven suspects is a confirmed crack smoker…What does that tell you?

The fingerprint, if it could talk, would probably say,

“Look, I’ve told you the guy smokes crack. What else do you want? You know what they say…If he walks like a duck and quacks like a duck…he’s probably the killer.”

But can a single fingerprint provide that sort of information? Sure it can, and here’s how.

Our bodies deposit metabolites—tiny traces of what we’ve consumed—into the sweat released from the pores located in our fingerprint ridges. Scientists use gold nanoparticles to detect the metabolites in fingerprint sweat to learn what, exactly, that individual has taken into his body, such as cotinine, a metabolite of nicotine. And the beauty of detecting cotinine is that a person would have had to ingest it, not merely touch a tobacco product, for it to show up in test results.

The process is simple. Dab the print with a solution containing gold nanoparticles with attached antibodies that bind to the metabolite. Scientists then apply a second antibody, one that binds to the cotinine antibodies. This solution also contains a fluorescent dye. If the person is a smoker, the dye will then glow along the ridge patterns when exposed to an alternate light source.

The test is also capable of testing for alcohol and drug use, which could help narrow a field of suspects. If the test detected cotinine and the guy you’re looking at for the murder is a non-smoker, then you need to at least start looking for an accomplice.

“I always wanted to be a detective when I grew up, and I’ve finally made it. Now, if I only had somewhere to pin a badge…”


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Want to learn more about fingerprints and the equipment used to detect them? How about bloodstains? Well, you’re in luck. A team of experts from Sirchie Fingerprint Laboratory will be on hand at the Writers’ Police Academy and they’ll be presenting a couple of mind-blowing demonstrations. Bring your questions and your cameras!


* Have you reserved your hotel room for the Writers’ Police Academy? If not, please do so today. The block of rooms we reserved at the Embassy Suites is nearly full and there may not be any additional rooms available once those are gone. You won’t want to miss out on any of the fun! Ask for the Writers’ Police Academy discounted rate.

* Also, spaces for the Writers’ Police Academy are filling fast, therefore, we may be at capacity soon. So register today for this one of a kind event. Remember, Sisters in Crime will pay over half of your registration fee! This offer is open to everyone. See the WPA website for details.







3 replies
  1. Diane Gilbert Madsen
    Diane Gilbert Madsen says:

    This was so interesting. Thanks for sharing with us. I always read what you send. I’m sure to deposit metabolites of this fingerprint information all over my house today! (Much better than drugs or alcohol.) Great stuff.

  2. Maggie Toussaint
    Maggie Toussaint says:


    I love your personalized fingerprints. It’s amazing how far technology has come and what a forensic team can do with a tiny bit of evidence.

    I’m very much looking forward to Writer’s Police Academy. Hope to also see you at Killer Nashville.


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