CLPEX Chat Board

In a trial scheduled for Aug 25, James K. Crump of the Mass State Police Crime Services Section will testify about the factors leading to lack of recovery of usable
fingerprints on a gun and ammunition and will also testify that identifiable fingerprints are recovered from firearms and ammunition in less than 5 percent of all examinations.
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I know resources devoted to examining firearms evidence has been a hot topic here. Thought y'all might be interested.

Hi, Lisa,

I think this related to our earlier discussions about negative testimony from about July 22.

I am curious as to where, or from whom, the Mass examiner derives his statistics. Is this based on his own case experience, the total experience in the Mass lab(s), or is he referencing a published study? If there is a formal study, I would like to obtain a copy of it for my files.

Less than %5 sounds quite reasonable to me, based on mine/our experience in our shop here in VA. I cannot recall the last time we recovered print suitable for identification from a gun. I hear occasionally, one is found on the receiver of a semi-auto pistol, or the magazine. However, this is quite rare.

In fact, over lunch today, my colleague & friend who is a retired CLPE from Washington, DC PD, told me they rarely obtained usable prints from guns, and they get lots of cases involving guns, as you can imagine.

Is this your case??

Thanks,

Bill

(I wish this format had spell-check!)

Good morning!
Not my case, tho I have traded some email with the person handling it. I've heard comments from other Mass attorneys about a variety of estimates given by Mass. examienrs. The new BPD unit is said to be getting results as high as 10-15% of partial latents, but a somewhat smaller number of latents suitable for matching.

I suspect this is going to be the examienrs' impression, not a study or even review of records. If I hear more, I'll let y'all know.

I don't keep statistics on this, but I know we, at the Worcester, MA PD LPU, do better than 5%. In my experience, it's not so much the surface of the firearms or the methods used that's the issue, but rather the way the firearm is collected, packaged and transported to the Latent Print lab. In those cases when our LPU Examiners go to the scene and retreive the evidence themselves, our chances of obtaining usable prints increases significantly.
DG

David Grady wrote: In my experience, it's not so much the surface of the firearms or the methods used that's the issue, but rather the way the firearm is collected, packaged and transported to the Latent Print lab. In those cases when our LPU Examiners go to the scene and retreive the evidence themselves, our chances of obtaining usable prints increases significantly.
DG

That's what I would expect. The degree to which officers are trained to handle sensitive evidence has an awful lot to do with it. I would say firearms are one of the most mishandles classes of physical evidence, from a latent print view. The potential danger tends to have them manipulated more than other pieces. They may be moved initially to get them away from an EMS treatment operation and again to render them safe. And I've seen them laid on back seats and in hot trunks and rattled around in both paper and plastic bags. It's entirely reasonable to characterize the probability of developing usable latents on a firearm as much lower than the layperson would imagine for an object that's held in the hand. It would be interesting to properly collect pistols from officers after a day at the range and see how many produced good prints. That might be biased, though. More and more common duty weapons have finishes far less amenable to good latents than they did when the common finish was polished blue.

Didn't the ATF study (1995ish) put it at about 10% ?

The following is from an article by Clive Barnum and Darrell Klasey of the Bureau of Alcohol, Tobacco and Firearms from California and was printed in the JFI Vol. 42, #2 (Mar/Apr 97) issue.

2nd Paragraph

In the examination of 1,000 firearms from February 1992, through August 1995, 114 identifiable latent prints were developed on 93 firearms. Although successful recovery occurred in approximately one of ten firearms, it should be understood that not all identifiable latent prints might have been left by an offender. Some developed latent prints, for example, are subsequently identified as belonging to a person involved in the collection of the evidence.2

They go on to say in a footnote that of the 114 latent prints developed, 24 were identified as coming from an offender and one was identified as coming from a law enforcement employee.

I would like to say as well it is also dependent upon the time frame from when it was collected to the time it was processed. In a differnet study by the US Army Crime Lab they were able to increase the number of latent prints recovered by processing as soon as possible with CAE Fuming. Although their study was all kinds of evidence it would also improve the number of latent prints on firearms.

Barnum and Klasey did not specify in their article the average amount of time from when the firearm was collected and when it was processed.

I have Barnum and Klasey article in word if someone wants it. It is very interesting and I think very well put together article.

All the responses so far have delt with the firearm. No one is addressing the ammunition? I recall a previous posting (I think?) where some had the good fortune of obtaining usable latents from expended cartridge cases. I can say in my 20+ years experience, I can only recall a couple of instances where we did actually get usable latents (cyanoacrylate and powder) but the prints belonged to the investigating detective (Duh-)OH!). Has anyone had success in this area? And how often?

PCC see page 2 of this forum for "May 14, 2008" under the thread "Need Published Studies......" and you should find your answer or at least part of it.

Ten percent is probably a reasonable average. How a firearm is handled not only when it is collected but also prior to that would significantly influence surfaces where prints might be developed. Many firearms are recovered in mud or water and often have been whiped.

I seem to develop more identifiable prints under the grips and on the frame area protected by the grips.

Hello All,

I have recently left BPD, and we had some remarkable results as to the recovery of latents on firearms. We had trained and the department equipped the Crime Scene Unit and the Districts with the tools to CA fume the firearms on the scene prior to submittal to the lab. If memory serves, we were recovering latents from firearms approximately 25% of the time, with approximately 20% of the firearm cases having latents of value. I believe IDs were being made around 12% of the time. We ofter refer to the ATF article and their average of 10% when testifying and explaining the procedures to outside personnel, however, the early processing on the scene prior to submittal was a huge asset in our opinion, and a key factor in those stats.

Andrew Reitnauer
NYPD Crime Laboratory
Latent Print Development Unit

I think that there needs to be more research on this too and that we shouldn't just base our numbers on one study from 10-15 years ago. I sometimes think that those numbers get repeated so much that examiners start off processing firearms believing that they aren't going to find anything. That should not be the way our discipline approaches processing evidence. The firearms examiners in my lab wanted to get a number to pass on to officers that they were recently training in regards to submitting firearms to the lab for latent prints. The firearms examiners had always been told the number was between 5-10% based on the ATF study. I have always heard those numbers too but thought it was low based on my own experience. So just recently I went through all of my cases from the last 3 years (those were all the reports I currently had on my computer) in which firearms, ammunition and magazines had been processed. Just as I suspected based on my own experience my numbers for latent prints developed on firearms were pretty high. In that time I processed 39 firearms (21 cases) in our lab and 20 of those firearms from 14 different cases had latent prints of value for comparison which I was subsequently able to id to 9 different people in 7 cases. I processed approx. 400 rounds of ammunition (14 cases) and was able to develop latents on 20 of those in 7 cases. The number of rounds processed is pretty high because some of those cases included boxes of ammunition in which I would not expect someone to touch each individual round but I processed each one separately regardless. I processed 36 magazines (16 cases) and developed 17 latents in 9 cases. If you calculate out the percentages for latent prints developed on firearms it is upwards of 50%. I can't give you good percentages on the ammo and magazines because it is possible that multiple impressions could have been located on a single item. I didn't necessarily keep record of that when I was going through my reports, but you still get about 50% of the total cases worked had latents developed.

I work for a State lab so none of these cases are necessarily getting processed soon after the crime has occurred (more than likely 3-6 months later) which would be more conducive for preserving latents, they come to us in a variety of packaging methods and have likely not been handled in the packaging with the greatest of care before I retrieve it. I will say that in my experience the most crucial aspect for whether latents will be found on a firearm is whether you have done a thorough visual exam using natural lighting and an ALS. I have noticed way too often that when I have found and imaged a latent after a visual exam and then proceeded onto CA, that the CA has coated over the latent and completely obscures it pretty much rendering a dye stain useless for that particular latent. My thought for why this has happened is because the CA molecules can not distinguish a significant difference in the latent print residue and the oils/residue already on the firearm.

The results I have were based on a relatively small number of cases and maybe even more importantly, it is based on my opinion regarding what is of value for comparison, which is due to my own experience and the amount of time I spend doing comparisons. I would just recommend that examiners don't rely solely on the ATF study, keep track of their own numbers, and do complete visual exams.