 Mystery: November 08, 2006 Issue [#1369] |
  Mystery
This week: Edited by: Tehanu  
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It has long been an axiom of mine that the little things are infinitely the most important.
--Sir Arthur Conan Doyle, A Case of Identity
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I had the opportunity to interview the forensics expert who took my second set of prints. Investigator DiGiulio has been a police officer for twenty-five years and a forensics expert for about half that time. He works in Albany, NY, USA, and his answers primarily pertain to that region.
Our conversation works best written out as a Q & A session.
 Note: I fleshed out Inv. DiGiulio’s reponses from my shorthand notes; the answers are not verbatim.
Do police officers and forensics experts get similar training when it comes to taking prints?
Police officers are trained to take fingerprint impressions at their Police Academy.
Forensics experts are trained to lift latent prints through state courses. NY's Division of Criminal Justice Services (DCJS) offers two courses called “latent level 1” and “crime scene.”
How difficult do you feel it is to take accurate prints?
It depends. There are many variables, like surfaces and weather. For instance, a vehicle sitting in the sun can get pretty hot and lifting tape might stick. There are other ways to go about obtaining the print that are not all that difficult, but you have got to think about it first.
Which is better – DNA analysis or fingerprinting?
Each has its pros and cons. Let’s say you find a partial print. Basically a fingerprint IS DNA. The print may have a good number of points - or swabbing it could provide a decent DNA sample. You have to decide what to do with it.
Finding palm prints is very helpful as there is so much more unique surface area and so many more opportunities to compare points. In fact, New York City has an entire database of palm prints obtained through major crime investigations.
Then there's the issue of twins. Twins share identical DNA but will not have identical fingerprints.
Can a criminal really leave someone else’s print at a crime scene? How effectively?
That is difficult to answer. To get someone else’s print, you usually need to lift it and then the fingerprint is reversed. And a lifted print may show from what type of surface it was taken; for instance if a print is left on wood, when the investigator dusts for the print, the powder might showcase grain marks. If the print was transferred from one type of surface and left on another, an investigator can see that. Also, in lifting a print, you lose some of the image.
Can a criminal really wipe a scene clean?
Yes, that’s possible. However if no prints are found, consider Locard's theory*. For an example of Locard's theory - let's say you own a cat. Cats shed a lot and it is likely that cat hair will get on your clothing. If you leave your house and go sit in a chair somewhere else, you will probably leave behind cat hair. You will also leave behind skin particles and so forth. It is also possible that you will pick up something from that chair, like loose fabric fibers. This is all trace evidence that can link you to a scene, but collecting this sort of minute evidence can be difficult, especially with time constraints.
What method do you use when lifting and comparing prints?
You really shouldn't lift prints AND compare them. For checks and balances, I lift prints and then send them to a DCJS latent print lab in Albany.
Ninhydrin is still good, still used. Basically it is a crystal that dissolves in solution. It's more expensive...using acetone is less expensive. We've got to be careful about budgets and cannot be like CSI on television. For instance, on the show they might use a scope that's worth about twenty thousand dollars. It'd be great to have that; it would speed up cases. But most police stations cannot afford that.
By the way, I consider a CSI unit to be a "jack of all trades." They identify, preserve, protect, and collect the evidence. But in real life they usually do not examine what they find. There's not enough time in the day to do all that. On TV a CSI unit finds and lifts a print within a minute. In real life it may take up to four hours. And sometimes criminals are "non-secreters" - they do not sweat enough to leave prints. Or they leave prints that are so smudged they're unusable. We do not always find something to use as substantial evidence.
Suggest any reading material?
There's a lot! I usually go on the internet and look for articles on print development. The technology is always changing.
***
In talking with Inv. DiGiulio, John~Ashen  ’s question from the last newsletter was legitimately answered. Inv. DiGiulio confirmed that the state of New York has no requirement concerning the amount of points needed to use a partial print as evidence in court. I brought up that I thought overall the U.S. does not ask for a particular amount of points. He said that is pretty much true but each state may have its own laws concerning using partial prints as evidence. So – if you decide to write about using fingerprints as evidence in court, check out your character's state or country laws.
At the end of our conversation, Inv. DiGiulio suggested I speak with the DCJS's supervisor of latent prints. His contact was unavailable, but I did get the privilege of obtaining more cutting edge information from the Deputy Commissioner for Criminal Justice Operations, Daniel M. Foro:
Do you think taking palm prints will become standard procedure?
Yes. We are updating AFIS to be able to collect and store palm prints. We are also connected to NYC's database of palm prints. The DCJS and the FBI are working on upgrading our systems to allow palm prints.
One third of latent prints are palm prints. A lot of agencies are collecting them.
What method do you use in comparing prints? How accurate do you feel computer databases are for comparing prints?
We use a version of AFIS**. This system uses an algorithm to do matching. It takes measurements between neutral points and then uses a scoring system to match fingerprints.
I would say there is close to 100% accuracy - high 99+%. It depends on whether you are matching ten prints (previously rolled prints) to prints rolled after an arrest or to latent prints lifted from a scene of crime.
It's really accurate - we've found a match to even just a small piece of the finger, a tip of the thumb.
***
I obviously find fingerprinting to be a fascinating subject and I was impressed with these two interviewees' openness in imparting their knowledge of latent prints. Deputy Commissioner Foro offered for me to visit and view an AFIS in action. And Inv. DiGiulio, when asked, told me more about a local Civilian Police Academy. Students attend "class" three hours a week to learn what it is police officers do, from listening to guest lectures on topics like forensics and criminal investigations to actually riding along in a patrol car. (I intend to enroll in it when it is offered next year!)
If you want to write a realistic story on various aspects of fingerprinting, do not rely on television. I urge you to research this fascinating subject and check out what local resources are available. Talking with people who actually lift and compare prints was thrilling and definitely made me feel more prepared to follow in Agatha Christie's footsteps. I hope this newsletter helped inspire and inform you as well.
*Edmond Locard's Principle of Exchange states that when any two objects come
into contact, there is always transference of material from each object
onto the other.
**Automatic Fingerprint Identification System |
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Questions
Each person who responds to these questions and/or sends feedback on this week's newsletter will receive one hundred GPs. 
What do you find mysterious about Writing.Com? and
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Thanks for the feedback!
writetight:
Excellent newsletter, Tehanu. *Note to self: wear gloves.* Dan
billwilcox:
What an awesome newsletter. I think I'm ready to join the CSI Team now!
Vivian  :
Thanks, Tehanu, for another newsletter to print in order to add to my files for mysteries.
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