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Category Archives: Fingerprints/Patterned Evidence

How Old Is That Fingerprint?

Fingerprint

Fingerprints are useful forensic science tools. They’ve been so for over 100 years. Mainly, it’s the pattern of the ridges on the fingertips that supply the useful information. We know that everyone has different fingerprints and we know that they do not change throughout the person’s life. This means that they are highly reliable sources for identification and for discrimination between two individuals. Law enforcement has employed this for years.

But several newer techniques and analyses allow investigators to go even deeper. The skin cells, that are part of a fingerprint, can often yield DNA. Chemicals in the print residue can sometimes reveal if the person has used or handled such substances as cocaine. Other analyses are underway that might make fingerprints even more useful.

One question that frequently plagues crime scene investigators is exactly when a print was laid down. This determination can make a huge difference. Let’s say that a print is discovered at a homicide scene and the primary suspect says that he had been at that location but that that had taken place a week earlier. Not on the day of the killing. Is he telling the truth? Or simply trying to throw the police off and make an excuse for the evidence they collected against him? It would be nice to know if the print was 24 hours old or seven days old.

Research is currently underway by Shin Muramoto and his colleagues and they reported their initial findings in a recent article in Analytical Chemistry. They discovered that a chemical found in fingerprints known as palmitic acid migrates away from the ridges at a predictable and consistent rate. By looking at this migration pattern they are able to determine whether the print is fresh or up to four days old. They are looking to extend this envelope to a longer period of time. But you can see, that even this level of discrimination could help—or not—- the suspect in the above scenario.

 

Q&A with Expanded Audio Discussions Now on the Suspense Magazine Website

Q&A with Expanded Audio Discussions Now on the Suspense Magazine Website

Check out the new posts John Raab of Suspense Magazine and I put together. Read the Q&As and listen to the expanded discussions. Hope each proves helpful for your crime fiction.

Can DNA Be Used To Identify Multiple Assailants In a Three Decade Old Rape?

http://suspensemagazine.com/blog2/2016/12/20/d-p-lyles-forensic-file-episode-1/

In 1863, Could An Autopsy Accurately Determine the Cause of Death?

http://suspensemagazine.com/blog2/2017/01/09/in-1863-could-an-autopsy-accurately-determine-the-cause-of-death-d-p-lyle-answers-this/

Can My Female Character Cause Her Pregnancy To Become “Stone Baby” By Shear Will?

http://suspensemagazine.com/blog2/2016/12/31/can-my-female-character-cause-her-pregnancy-to-become-stone-baby-by-sheer-will/

More to come.

Want more cool questions from crime writers? Check out my three Q&A books.

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More Info and List of Included Questions

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More Info and List of Included Questions

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More Info and List of Included Questions

 

Will 3D Printed Fingerprints Unlock a Phone?

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Can someone’s fingerprint be reproduced by 3-D printing technology and if so can it be used to unlock a cell phone? This is intriguing science and currently Professor Anil Jain at Michigan State University is looking into developing this technology. One of the problems is that many cellphone fingerprint security measures require not only pattern recognition but a certain degree of electrical conductivity that is natural to human skin. How to reproduce this in a 3-D printed model is one of the hurdles Professor Jain must overcome. But it is intriguing and we will see how it all shakes out.

 

 

 

FORENSICS FOR DUMMIES Release Day

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Forensics For Dummies Updated 2nd Edition is now available.

Get it through your local Indie Bookstore or here:

Amazon: http://www.amazon.com/Forensics-Dummies-Douglas-P-Lyle/dp/1119181658

B&N: http://www.barnesandnoble.com/w/forensics-for-dummies-douglas-p-lyle/1013991421

 

Forensics For Dummies, 2nd Edition Coming Soon

 

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Just got the new cover for Forensics For Dummies, 2nd Edition.

It will be released from Wiley on 2-29-16

Pre-Order now

 

Stupid Criminals: Man Attempts to Gnaw Off His Fingerprints

Damaged Print

If you have a record or an outstanding warrant or two, you might not want the police to ID you when you’re arrested for driving a stolen vehicle. I truly hate days like that. But, what to do? Maybe just gnaw off your fingerprints and they won’t be able to determine your ID. Probably painful, and probably won’t work. It looks like Kenzo Roberts gave it a whirl (no pun intended) anyway.

And he’s not alone. Many folks have tried to alter their fingerprints with cuts, burns, scrapes, and other painful procedures. Even Public Enemy #1 John Dillinger tried. Besides having plastic surgery to alter his face, he also attempted to burn away his fingerprints with acid. That didn’t work either.

John Dillinger

John Dillinger

FROM HOWDUNNIT:FORENSICS

FORENSIC CASE FILES: JOHN DILLINGER

John Dillinger was one of America’s most notorious criminals, once named Public Enemy No. 1. In an effort to evade the cops, he underwent facial plastic surgery and tried to remove his fingerprints with acid. After his betrayal by the famous “Lady in Red,” Dillinger was shot dead outside Chicago’s Biograph Theater. Prints taken at the morgue proved that the dead man was indeed Dillinger. The acid had damaged only a portion of his finger pads, leaving enough ridge detail for matching with his prints on file with the police.

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Fingerprint Toxicology: Your Drug History in Your Prints

When someone takes cocaine, they experience all its effects fairly quickly. Also, the body immediately goes to work destroying the drug. That’s what the body does. With all drugs. That’s why you have to take your blood pressure med everyday. If the body didn’t break it down, a single pill would last a lifetime—theoretically. But Mother Nature is too clever for that.

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Drugs begin this metabolic break down almost as soon as the hit the bloodstream. In the case of cocaine, the breakdown products (called metabolites) include benzoylecgonine and methylecgonine. These products are then excreted by the kidneys and can be found in the user’s urine. But they are also excreted by the sweat glands—which are in many ways just a bunch of little kidneys—-so that these chemicals can often be found by toxicological examination of a deposited fingerprint.

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This could prove useful in determining if a offender was under the influence, or had at least recently used, cocaine.

But it’s not just for cocaine or other illicit drugs. Such testing might be able to determine what medication you take and even what you had to eat.

 
 
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