Wednesday, February 10, 2010

Fingers That Don't Leave Prints

Sandra Parshall


Did you know that your job, your medication, or simply growing older could cause you to lose your fingerprints?

I thought (as most people do, probably) that fingerprints were forever, unless they were cut off or removed with acid, but an article in the February issue of Scientific American points out various commonplace circumstances that can alter or eradicate prints. Science writer Katherine Harmon gathered the information from experts in the field.

I am, of course, interested in this topic only as an author writing about crime. If I want to write about a character whose fingers leave no prints, how can I make it believable?

Harmon reports in her article that it’s not unusual for bricklayers to wear away their prints if they routinely handle rough materials without gloves. Handling lime can burn away prints. The most startling news is that secretaries can lose their prints by handling paper all day. This makes sense, though: paper, after all, is made from wood, and it’s not as smooth as it looks. It produces enough friction, over time, to wear down the ridges on fingertips.

If I don’t want my character to be a bricklayer or a secretary, I can give him or her a bad case of poison ivy on the hands. Rashes can remove prints – temporarily. If only the surface layer of skin is affected, it will regenerate quickly, complete with prints.

I could give my character a history of cancer treatment. Some cancer drugs can cause chemotherapy-induced acral erythema – swelling, pain and peeling of skin from the hands and the soles of the patient’s feet. Fingerprints will peel off. Annals of Oncology reported in May 2009 that a man from Singapore who had undergone chemotherapy was detained briefly on a trip to the U.S. after a routine security scan showed that he had no fingerprints.

Making the character a person of a certain age might also work. Growing old may not obliterate prints, but it can make them difficult to capture. As skin ages, the ridges on the fingertips become less prominent and the furrows become narrower, so prints will be less distinctive.

Forget about mutilation with acid or a knife – the prints might be gone, but the unique scars left behind will be every bit as incriminating.

My internet research into the possibility of changing or removing one’s fingerprints turned up a lot of sites that suggested sanding them off. But if mutilation, illness, occupation and age don’t fit the story, the simplest approach may be having the character cover his or her prints by applying a polyurethane glue such as Elmer's Ultimate. It may be uncomfortable after it dries, though, and no solvent will remove the stuff. Sooner or later it will wear off. The big advantage is that the glue is invisible and the fingers will look normal. No one will suspect a thing.

Good to know.

You can read Katherine Harmon’s article here: http://tinyurl.com/l7t6mv

16 comments:

Dave Chaudoir said...

Sandra, I remember Leann Sweeney talked about this over at Cozy Chicks (or Writers Plot?) last year. She needed to be fingerprinted in Texas to renew a nursing license or something, but she couldn't give a good fingerprint! It is an interesting phenomenon. By the way, BROKEN PLACES is in the mail on its way to me, my first Parhsall!

Barb Goffman said...

Hi, Sandra. A little family story: My grandparents used to own a liquor store, and for whatever reason my grandmother was the one to get whatever license the state required. Back then (perhaps still now?) you had to be fingerprinted, but my grandmother had no prints. The state employees, supposedly, were amazed, and they gave her the license anyway. So how'd she lose her prints? She was the oldest daughter in a family with 9 or so kids. Best guess is that after so many years cooking and washing with her hands in steaming water, they had simply worn away. I always found that so very cool (in a mystery writer sort of way).

Sandra Parshall said...

I tried out the fingerprinting scanner at the Museum of Crime and Punishment, and it couldn't get more than a very faint print from me. I can see ridges and swirls on my fingertips, but the device picked up almost nothing.

Jessie Crockett said...

My sister tried to be fingerprinted as part of a background check run on potential substitute teachers. Her ridges were completely flattened out but still visible to the eye. She was told her passion for knitting was the most likely culprit.

Leann Sweeney said...

I am one of those people without "readable" fingerprints. They just come out as ugly black smudges without any ridge detail. I'm a nurse and thirty years of constant handwashing made me able to commit the perfect ... no. I won't go to the dark side. Promise. :-)

L.D. Harkrader said...

On the flip side, I learned this weekend at our local Sisters in Crime meeting that figerprints will go through latex gloves. Our speaker was a crime scene investigator, and she said latex gloves only keep you from leaving prints for a short while. After that, because of body oils, sweat, etc., the prints come right through. She said that when they process a scene, her team of investigators usually change their latex gloves about every 15 minutes so they won't contaminate the scene with their own prints.

signlady217 said...

L.D.--I did not know that about latex gloves. Interesting. I've always found it hard to work with any kind of gloves on, partly because my hands are pretty small (my wedding rings were size 3 &1/2!) and even small gloves are usually big on me.

Jan Buck said...

Great article, Sandy! Very useful and timely for me (ah, I mean for my villain, of course!).

Marilyn Meredith a.k.a. F. M. Meredith said...

I owned and lived in a licensed care facility. When my mom came to live with me (she was in her 90s) I needed to get her fingerprinted--they tried twice at the police station and couldn't get anything. The licensing agency relented and let her stay.

Marilyn

Robin Burcell said...

Count me in as one who does not have readable fingerprints. Before I became a police officer, I was a bookkeeper, counting lots of money for a large retail chain store each and every day. I had only done this for a few years. I became a cop at the age of 23. But apparently the constant handling of checks and money five days a week for about three years was enough.

When they were doing my background prints to become a police officer, my print card was kicked back several times by the FBI as not being readable. (Not all, just the couple that I used to flip over the checks as I was adding them up. The #3 and #4 fingers on my right hand. And part of my right thumb.

Those prints are still unreadable to this day. (I had the live-scanned a few years back for a new background. They just get kicked back immediately on the screen.) But one must remember that there may still be identifiable features, such as scarring, or even the tiny wrinkles. So one can still be tentatively ID'd from a "typically unreadable" print.

Lonnie Cruse said...

Cool post, Sandy. The best way I've seen to GET prints is to give someone a roll of the wide tape you use to tape packages. I can't use it without getting my prints all over it.

Carolyn J. Rose said...

When I was fingerprinted for a job with the local school district the process took about an hour. We had to ink, roll, ink again, try a new type of paper, etc. The technician said my age (early 50s), the amount of bare-handed housework I'd done over the years, and my career keyboarding at top speed as a TV news producer wore away the ridges. Harpists, she said, also lose their prints.
Makes you wonder how so many older criminals get caught through prints left at the scene - Carolyn J. Rose (www.deadlyduomysteries.com)

Sandra Parshall said...

It really does make me wonder, Carolyn. This is something I have never seen explored in a mystery.

DayAlMohamed said...

Although I am primarily a technology-user, perfering to do my "reading" using screen-reading software on a computer, I still do read braille. The article made me wonder about other visually impaired folks who perhaps do much more braille reading and how that might impact their fingerprints. Thanks for the great post and reference.

Lenore said...

Wow - I never thought about all the ways you might lose your fingerprints. Thanks for the incredibly interesting post.

Anonymous said...

my mother was denied renewal of her visa because they can not read her fingerprints. someone told her to stop using bleach so much - she uses bleach to wash dishes and clothes almost daily. I couldn't believe it!