Subject Elimination on a Print of No Value

[Kasey Wertheim]

I would also be interested to see the print in question.

But the larger issue is distortion, which I find to be an interesting topic.

Would everyone agree that the recognition of distortion is part of what you are trained and experienced in as a latent print examiner? In other words, you become an "expert" at identifying something as distortion rather than difference. To some examiners, they may not be willing to accept a particular anomoly and therefore won't "call" the ID, whereas an experienced examiner may immediately recognize the anomoly as distortion and make the ident. I have seen this quite a few times and I have some excellent examples that I use in training courses of strange distortions.

But it goes the other way as well. If, based on your training and experience you recognize that distortion does NOT hinder your ability to reliably determine level 1 information, and that in fact there is sufficient quality and quantity of level 1 ridge flow information to determine (within tolerance) ridge flow that is definitely NOT that of any of the 10 fingers of an individual, then I think you are on solid scientific ground in declaring an exclusion. The keys here are the same keys SWGFAST uses to define exclusion:

1) "Competent" examiner (training and experience)
2) Applied to all comparable anatomical areas, (all 10 fingers)
3) Presence of a discrepancy (ridge flow out of tolerance for clarity)
4) Based on sufficient quantity and quality of the friction ridge details,
5) Reproducible conclusion (verification)

[Michele Triplett]

This is actually in response to something Mike said above. I guess I'm a little slow at responding.

Mike,

You said, “If you cannot say it is positive or negative then it is inconclusive. The term we have always used in this case is that the print is not of comparison value.”

I think most people understand inconclusive to be a result meaning you can’t make a conclusive determination, where as stating, “the print is not of comparison value” sounds like you’ve made a conclusive determination.

I commonly use ‘inconclusive’ as my result but the reason why it’s inconclusive always varies. Sometimes I have a small section of ridge detail and I’ve searched and searched but can’t individualize it or exclude this person as the donor. My result is inconclusive and the reason why is because I can’t individualize or exclude. This could be due to my level of experience but it doesn’t mean that “the print is not of comparison value”. Other times I’ve compared a latent to the exemplars and it was negative to the #1-#9 fingers but the #10 finger was too smeared to complete my comparison. In this case my result would be ‘inconclusive’ and the reason why is because my analysis isn’t complete. I need better exemplars. I can think of a lot of other times where inconclusive is appropriate but I’ve never used it to indicate that “the print is not of comparison value”

Michele

[Mike]

Michele,

In the context of this thread we are talking about a print that lacked sufficient detail to identify and likely was distorted. That is what I meant by "not of forensic value". I was not writing about the other scenarios you described.

I would agree "not of forensic value" sounds like a conclusive statement. This does not strike me as any sort of a problem, but I am not usually the type that likes to dissect the semantics of these things.

Mike

[Shane Turnidge]

I guess the first thing that comes to my mind is what other evidence is there against the suspect in this case?

Purpetrators do not always leave prints on touched surfaces. The absence of a print attributed to your suspect does not mean he/she wasn't involved.

The fact you have developed a partial impression with level one detail suggests that this print is indeed of value. Can level one detail be subject to gross deviation? You bet! Just take your own finger behind your fingerprint glass and see what you can do to your own ridges. (I can make my ulnar loops nutant )

The presence of level one detail is indeed valuable. However, with apologies to Ridgeology, you would have to have been schooled in the Henry system to know the true value of the classification you have.

Shane

[Mike French]

The keys here are the same keys SWGFAST uses to define exclusion:

1) "Competent" examiner (training and experience)
2) Applied to all comparable anatomical areas, (all 10 fingers)
3) Presence of a discrepancy (ridge flow out of tolerance for clarity)
4) Based on sufficient quantity and quality of the friction ridge details,
5) Reproducible conclusion (verification)

Kasey,

After further consideration and attempting keep my argument within SWGFAST guidelines I offer that an expert cannot exclude with absolute certainty when I print is distorted to the point of exhibiting level 1 detail only.

Based on prerequisite #4 there needs to be sufficient quantity and quality (clarity) to render such an opinion.

If increased clarity enables us to more accurately assess the original ridge characteristics that made the impression, then the opposite holds true as well. Decreased clarity should make us less certain of the original ridge formations. As for me I cannot be less certain and absolutely certain at the same time. I don’t believe any amount of experience will give me those powers.

I think that an examiner testifying to absolute certainty on an impression that only contains only level 1 detail is fooling himself since absolute certainty cannot exist without clarity.

I think if one chooses to engage in such testimony, a statement of probability is the only sound response.

[David Fairhurst]

For years I have used the following argument when people have talked about individualising solely on level 3 detail.
Level 3 detail cannot exist without level 2. If you can see the edges of the ridges, you must be able to trace their paths.
Level 2 detail cannot exist without level 1. If you can trace the paths of ridges you can observe trends in their flow.
So all 3 levels of detail are present in any print. It is just their clarity which varies; sometimes falling to the point at which that level of detail cannot be held to be reliable enough to use in the individualisation.

In this discussion I would turn this argument around.
How can you observe trends in ridge flow and patterns if you cannot trace any ridges? Level 1 detail cannot exist without level 2.
How can you trace the paths of ridges if you cannot see their edges? Level 2 detail cannot exist without level 3.

You cannot, therefore exclude solely on level 1 because level 1 does not exist solely.
I do agree however, that you can have sufficient clarity to exclude without sufficient to individualise.

[Dennis Degler]

[David Fairhurst]

WITH ANY CERTAINTY

This is the knub of it.
If level 2 clarity is so low that you cannot be sufficiently certian of the presence or location of ridge path deviations then you cannot individualise.

[Guest]

[quote="David Fairhurst"]
You cannot, therefore exclude solely on level 1 because level 1 does not exist solely.
quote]

Now I'm really confused.
Would you agree, David, that what matters is not what exists, but what you can see? If you cannot make out the level 2 detail WITH ANY CERTAINTY, then why can't you exclude solely on level 1 detail?

[Dennis Degler]

[David Fairhurst]

Dennis,

it's a semantic point really.
A print - level 2 and 3 detail is so poorly recorded that an examiner cannot reliably trace the paths of enough individual ridges over sufficient length to individualise the source. However looking at the print as a whole the general direction and flow of the ridges can be discerned.
In such a case an examiner may exclude if the level 1 detail does not agree. All 3 levels have been observed and analysed but only the first needed to be compared to exclude the candidate, The second and third level detail was assessed as having no value for individualisation.