Interesting Tidbit 5

[Charles Parker]

This piece comes from an FBI document on the investigation of the Mayfield error. It goes well with a previous thread on this site that is talking about exclusions based upon L1D.

VII. Exclusions
The general practice in the field of latent prints is that of "making an identification." Simply because no latent print of sufficient quality and quantity was found with features similar to the suspect does not mean that the suspect did not handle the evidence. Someone can handle an object and leave no latent print(s); therefore, practitioners espouse that no one can ever be excluded as having touched the evidence. In keeping with this philosophy, a latent print examiner tends to approach the comparison to "make an ident," rather than to attempt to exclude. This concept is similar to any other forensic analysis in that a lack of evidence does not necessarily exclude a suspect. However, it contrasts slightly with the doctrine of other forensic science disciplines. In forensic science examinations, regardless of the discipline, a pattern or profile (or some other data) is generated from the evidence, and it is compared with that obtained from a reference sample(s) in an attempt to exclude the two samples as having originated from the same source. When an examiner fails to exclude, then some significance is placed on that observation or finding. The more powerful or resolving the analysis, the more likely it is that wrongly associated samples will be excluded. The tremendous variability observed in friction ridge skin makes analysis of latent prints one of the most powerful exculpatory tools available to the forensic scientist. In fairness, an examiner does look for discrepancies in ridge detail that would result in an interpretation of exclusion. However, this approach is implemented only for prints deemed suitable for comparison.
In the first step of ACE-V, the examiner analyzes a latent print to determine if it is suitable for comparison. However, some prints may not meet this criterion, but they may provide exculpatory information. This can depend on how one frames the focus for exclusion. As stated above, no one can ever be excluded as handling the evidence because a person can touch an object and not leave a latent print. Alternatively, a defendant may desire to know if there are latent prints on the object demonstrating that someone else did handle the object.

An example may illustrate the point. Consider the recovery of a latent print on a glass found at a crime scene. The print is degraded such that the quality of Level II and Level III features is too poor to proceed to the comparison phase of the examination. The print is therefore declared "of no value" and discarded. No further work will be performed on this print. In this scenario, the Level I features clearly present the pattern of a whorl. Now assume that a suspect is apprehended and his or her fingerprints (and possibly other areas of friction ridge skin) have no whorls. In this case, even though it lacked sufficient quality or detail for an identification, the pattern would have excluded the suspect as the source of any prints found on the evidence. The defense and prosecution may want to know if the evidence revealed that someone other than the defendant handled the evidence. Exclusions are a very useful investigative tool and are currently underutilized.

The issue of exculpatory power of evidence is complex but needs further investigation. Some interviewees suggested to the committee that patterns insufficient for an identification could be artifactual. Thus false-positive and false-negative results could be obtained. This needs to be further studied and documented. It would not be wise to recommend a procedure that may have an inherently high error rate. There also is a tremendous resource consideration. If it were deemed reliable to proceed with the exculpatory model, then a substantially larger workforce (and concomitant resources) would be needed, case backlogs would increase, and more storage facilities would be required.

[/quote]

[Heidi Fraser]

I agree with most of what was stated in this quote, except for this bit:

In this case, even though it lacked sufficient quality or detail for an identification, the pattern would have excluded the suspect as the source of any prints found on the evidence. The defense and prosecution may want to know if the evidence revealed that someone other than the defendant handled the evidence.

Surely they don't mean to suggest that because the pattern doesn't match the defendant for ONE print, that NONE of the prints on the evidence could be his? I wouldn't say that the pattern had excluded the suspect as the source of ANY prints on the evidence, but rather that it had excluded him as the source of THAT particular print. The others need to be analysed and compared individually.

[Charles Parker]

Heidi----good catch. I first thought I had typed it wrong then I remembered I did a cut and paste.

I think they just made a small (?) misstatement. It probably should read

.......the pattern would have excluded the suspect as the source of the print found on the evidence..........

Like you I do not agree with "any prints found on the evidence".

You should be a proof reader or on the editortial board.

Whatta yew chrge far prufreding. I gutta a latte.

(Sorry---the devil in me came out---That is OK---I just beat him back)

[Heidi Fraser]

You should be a proof reader or on the editortial board.

Whatta yew chrge far prufreding. I gutta a latte.

Lol. Isn't it my anal attention to detail that landed me this job?

Always happy to proof-read. I'm one of that dying breed who still feel personally offended when they see incorrectly used words, grammatical errors, and the like. I used to proof foreign students' theses for them to make extra money in grad school. *grin*

[sharon cook]

Too, to, and two......grrrrrr.... there, their, they're....GRRRRRRR
(I swear I must have been an English teacher in a previous life)

[Dennis Degler]

[Pat A. Wertheim]

Our favorite is in blood alcohol, where officers frequently submit a "vile of blood" for blood alcohol analysis.

[g.]

I've got you all beat.

I was reading a student's report and I think the student was relying on spell check a little too heavily (and had some language "deficiencies" to say the least).

The statement that the student meant to say was "the perpetrator was wearing a bandana on his face" but what he wrote, several times mind you, was "the perpetrator was wearing a baklava on his face".

Since then I have given up wearing sweet Greek desserts out in public.....=) I think I actually did a real "spit take" when I read that one.

g.

[David Fairhurst]

g.

Could it have been a balaclava that he was wearing?

D.

[g.]

Dave,

You're right! That's probably what he meant (I wondered how the hell spell check confused bandana with baklava....)...but that's probably what he meant, but then "Baklava" was what he wrote!

Well, given that, there are probably loads of police reports out there with criminals running around with sweets on their heads!

g.

learned something new today. thanks!

[PC]

One of my favorite reports that I was reviewing as a supervisor concerned a city liability. While in foot persuit of a criminal our officers damaged a wooden fence. However, in the report one word was routinely misspelled....boards was spelled broads. The report read.."There were broads attached to the fence and additional broads stewn on the grass and in the roadway east of the fence." I still chuckle over this.

[sharon cook]

Another pet peeve is "door jam." I wonder how you make door jam...I bet it doesn't taste very good.