CLPEX Chat Board

I'll keep it vague for starters if anybody wants to message me directly or email me, but I'm having to try to determine why there was an inconsistency in what the analyst was able to preserve vs what CTS thinks they should have on their latent processing tests that would have gone out in May/June. The analyst wasn't an outlier, ~15% of the people that took this test got the same result. Anybody else working on this?

Does CTS include what techniques they used to develop the prints they are reporting? I think the last time I took their processing test (2020 maybe), you are supposed to list the techniques you utilized. If you don't have a lot of techniques, it's possible that you aren't going to get the same development as they do. Also, if your analyst got additional development that CTS isn't reporting, RS&A had a processing test a few years ago where a lot of people developed additional latent prints on an item that weren't supposed to be there - meaning, they weren't cleaned fully beforehand.

Yes, when you look through their test report they list the residue component that they used to plant the print.

Sent you a PM.

Aaaaand now we have the results from CTS Test 22-5191. A full 30% of test takers didn't develop the print CTS expected them to on the newspaper and 71% didn't develop the latent print CTS expected them to on the photograph.

This is why I am not a fan of this test method for processing. A latent print is by definition a chance impression. That variable should be taken out of the equation somehow.

A few years back, RS&A had a processing PT that included a knife that wasn't supposed to have ridge detail on it. I don't remember the number, but there were several labs that reported ridge detail development on it when the expected result was supposed to be negative.

I don't know if PT providers are putting profit over quality (I would like to think not) but this does show you, as NRivera stated, that latents are chance impressions and just because you think you left one behind doesn't mean it'll always be recoverable.

In our lab, I am the one that creates the processing PTs for our CSIs as we have been able to show that the current providers aren't able to create a PT that meets our needs. Maybe that's something to think about depending on how many CSIs would need to be PT'd every year.

I agree with some of the points made in this thread. I believe that in latent print processing, a proficiency test should be used to demonstrate competency in using the sequential methods available. Rather than a comparative examination, labs all have a variety of reagents/techniques available to them, and they are all different. The test should focus on how the evidence/item was processed rather than the result. As was mentioned, latents are a chance impression, and may not always develop as "expected" (bad term). A couple years ago in my lab, we had 2 of 6 people not retain an impression on item because in their opinion it was not suitable for collection, since it had been subject to distortional factors and not enough information was left to warrant photographing. Which raises the question I know alot of units debate with PTs in processing: Should we photograph/lift/collect anything that develops since something was deposited, rather than use their knowledge to determine if the development is sufficient for capture. In my opinion, if you used an acceptable sequence, and any collection was performed correctly, you passed.

Andrew