CLPEX Chat Board

After printing out the SWGFAST “Standard for Latent Print Examinations Involving Two or More Friction Ridge Impressions as a Simultaneous Impression” I leafed through it looking at the pictures (I like pictures) and when I saw the large palm print and the large foot print with the markings I thought to myself “OMG, what are they doing”.

But then I sat down and read it. Actually I read it three times and then compared it to the previous document of which I had a copy of. There have been a few changes in the document. One of the most important is paragraph 6 on the very first page which states:

“If a conclusion can be derived without invoking simultaneity, or if the issue of simultaneity itself is not relevant, then this standard may not apply.”

Of course I was not at their discussion and going only from that above quoted paragraph and the rest of the document what I think it says is that if you are invoking simultaneity as the reason for your conclusion, then this document will apply. If your conclusion does not rest or depend on any aspect of simultaneity (just stand-alone) then this standard would not apply. That one paragraph says oddles about this document.

Shucks, half the LPE I know will not conduct simultaneous impression examinations so this document is a no-brainer. But if you find yourself in an examination where simultaneous impression(s) are a key element of your conclusion or presentation then these standards will most certainly apply. This document provides the basis for stepping outside the box when the need or the case requires it.

Now I could be wrong in my interpretation of this document and I guess I will find out more in Louisville. But for now if they keep that 6th paragraph intact, I have no problem with the document (a little rub here or there, but nothing I have to die for).

My 2 cents.

Of course I was not at their discussion and going only from that above quoted paragraph and the rest of the document what I think it says is that if you are invoking simultaneity as the reason for your conclusion, then this document will apply. If your conclusion does not rest or depend on any aspect of simultaneity (just stand-alone) then this standard would not apply. That one paragraph says oddles about this document.

Charles,

Bingo. As a member of that committee, that is exactly what we intended by that statement. If your agency does not approve simultaneous impressions, you aren't trained to do them, you have 50 simultaneous impressions but it's not probative or meaningful in the least bit, etc...then don't bother with this standard, just conduct business as usual. However, when you DO CHOOSE to REPORT an impression where simultaneity is an issue, is probative, or is the only way to effect the id (as in the MS v. Patterson case)...then this standard must be applied.

What we liked about that one paragraph is that many examiners will have one impression that stands alone and will say..."look, there's a stand alone here, no problems, just reporting out 1 ID". But when it really is probative to the case (e.g. how an item may have been handled) or when simultaneity is the very foundation for achieving the identification b/c none stand on their own, then this document is the standard that will be followed. I suspect that 99+% that it will be the former. But having said that, some agencies do routinely report out simultaneous impressions (where 1 or more stand alone) as a matter of business...great...this will work well for them.

At least that was the thinking on it to the best of my recollection and I think you need not worry, that phrase will stay in. There was a lot of discussion and when it was finally crafted, the light came on for all of us and we said "yeah, we need that right up front, in the beginning".

Does that help clarify?

g.

g.

It does most certainly.

But now you have taken away my excuse to go to the SWGFAST Open Meeting in Louisville in August. Nothing to talk about.

I finally finished reading the new simultaneous draft for comment. Although it’s currently in my agencies SOP’s that each latent must stand alone, you never know when that might change so I’m still interested in this document.

For the most part I think it’s great, I just have a few questions.
1st, in most of this document it talks about ‘supporting or refuting’, but in section 1.2.1 it states:

The following factors for each friction ridge impression and the aggregate shall be analyzed to confirm or refute that the impressions are consistent with having been deposited concurrently:

I’m wondering if the word ‘confirm’ could be changed to be ‘support’ to be in line with the rest of the document or if there’s a reason for the word ‘confirm’?

2nd, section 4.3 states:

Blind verification should be utilized where none of the impressions within a simultaneous impression stand alone.

I’m just wondering why this should be done? As far as I’m aware, BV isn’t a standard practice in our discipline, there’s no research to show it’s beneficial, when it’s beneficial, or how it should be used.

3rd, I know it’s common to write on lifts but just because it’s always been done this way doesn’t mean it’s a good practice. I really hate to see SWGFAST recommend this because once the lifts are written on then it’s impossible to have the originals re-examined. I can understand agencies writing on lifts, I just don’t think SWGFAST should encourage it.

4th, since the references are ‘general references’ that let people know where to find additional information, shouldn’t the Patterson case be referenced? Shouldn’t examiners be told that a court ruling on simultaneous impressions exists?

Any thoughts?

Michele wrote:1st, in most of this document it talks about ‘supporting or refuting’, but in section 1.2.1 it states:

The following factors for each friction ridge impression and the aggregate shall be analyzed to confirm or refute that the impressions are consistent with having been deposited concurrently:

I’m wondering if the word ‘confirm’ could be changed to be ‘support’ to be in line with the rest of the document or if there’s a reason for the word ‘confirm’?

Their language takes reasonably careful reading. I suppose confirming consistency is pretty much supporting the impression of concurrency. It's probably just that it's awkward to use "support" in the sentence. It might have been useful if they had actually articulated the idea that the cumulative value of the factors of consistency leading to a conclusion that the impressions were simultaneous has the same meaning as the cumulative value of consistencies between two impressions leading to a conclusion of identity.

Michele wrote:2nd, section 4.3 states:

Blind verification should be utilized where none of the impressions within a simultaneous impression stand alone.

I’m just wondering why this should be done? As far as I’m aware, BV isn’t a standard practice in our discipline, there’s no research to show it’s beneficial, when it’s beneficial, or how it should be used.

I sounds a bit like they are worrying more about conclusions of simultaneous impressions and are invoking something seem as more powerfully proof against bias. Is it true that the conclusion needs more rigorous checking than straight comparison? I haven't convinced myself of that. Consider two different modes of error:

1 - In common comparison, interpreting features in the latent based on imagined corresponding details in the record.

2 - In deciding simultaneity, using the fact that two latents in the cluster identify to the record to conclude they are simultaneous.

I don't see one as less troublesome than the other or more likely than the other.

Michele wrote:3rd, I know it’s common to write on lifts but just because it’s always been done this way doesn’t mean it’s a good practice. I really hate to see SWGFAST recommend this because once the lifts are written on then it’s impossible to have the originals re-examined. I can understand agencies writing on lifts, I just don’t think SWGFAST should encourage it.

I wonder, considering that we have ample means of making more or less duplicate images that can be marked up, why one would do it. I have, of course, marked on latent cards, but there has always been a niggling feeling that it's wrong to make anything but an identifying mark on evidence that seemed alright with latents just because it was commonly done.


They also don't address the meaning of one kind of inconsistency. What if we are presented with a cluster of, say, four impressions that look for all the world like simultaneous impressions of four fingers on one hand? When we examine them, we find that the 1st, 2nd, and 3rd have detail consistent with the record but do not stand alone, and the 4th has clear detail not consistent with the record. (Throw an exclusion into examples 1.4.4 and 1.4.5, Figs. 8 & 9.) The 4th (or make it the 2nd or 3rd) is perfectly consistent in position to be simultaneous but can't be sourced to the record. Does that destroy the simultaneity conclusion?

Michele Said

Although it’s currently in my agencies SOP’s that each latent must stand alone,

Michele, that is interesting. Most agencies that will not perform simultaneous impressions do not have it in their SOP, but it is kind of a unwritten law.

Why do you think----or do you know the history why they would have that in the SOP's? Was there a problem in the past-----or just a philosophical stance?

Michele Said
quote]3rd, I know it’s common to write on lifts but just because it’s always been done this way doesn’t mean it’s a good practice. I really hate to see SWGFAST recommend this because once the lifts are written on then it’s impossible to have the originals re-examined. I can understand agencies writing on lifts, I just don’t think SWGFAST should encourage it.[/quote]

Gerald Said

I wonder, considering that we have ample means of making more or less duplicate images that can be marked up, why one would do it. I have, of course, marked on latent cards, but there has always been a niggling feeling that it's wrong to make anything but an identifying mark on evidence that seemed alright with latents just because it was commonly done.

I took these two comments about marking on latent prints and moved them with my comments plus others on this forum to the Documentation under the Board Index. Click on Board Index and go to documentation if you want to see more on marking on lift cards.

Charles,

Our SOP on simultaneous impressions wasn’t written because of any problem, we just have some examiners with different views about whether it should be done or not and it was our managements opinion that it should never be done. We’ve had a lot of people retire in the last few years and I don’t think there’s anyone left from the group that made this SOP but nobody has ever felt strong enough about the issue to ask for the SOP to be changed (our SOP’s can be changed by a request from either examiners or management).

I only remember having one case that I’d even consider making an aggregate ID. In my case the latents (3 of them) had plenty of information in each one but the know prints didn’t have enough information (the three latent impressions were tips). I think I found about 5 common characteristics between each latent and known print and could only make the ID in the aggregate. Since our management frowned on ID’s based on simultaneity, I didn’t make the ID but I also didn’t feel bad about it because if the detectives could get better known prints then I could easily make each ID with each latent print standing on its own. I saw no reason to push the issue.

This entire concept of "individualization" supported or confirmed simultaneity in two separate, yet non-identifiable friction skin impressions seems non sequitur. It looks as if the [confirmation] that said impressions were made simultaneously is really a presumption ultimately based on the "average" shape of a hand or foot and an intuitive probability of orientation and similar directional smearing, etc.. rather than some [unique feature set] of the same. Of course, we would be referencing impressions that can't support individualization on their own. When I look to see what supported the conclusion of simultaneity, and subsequently individuation, I do not see supporting science; I see a leap of faith. The very key is the accuracy of our interpretation of the simultaneity. If we could determine the likelihood of simultaneity with an 87% probability, it seems unwise to build our tower of individualization upon such an unstable foundation. And then would anything change if we could routinely interpret simultaneity with an incredible 95% accuracy? An initial error in interpretation will cascade for both individualizations and exclusions.
....just another perspective.

Let me say first that I am a supporter of the use of simultaneity to support individualisation and to provide extra information on the anatomical and handling aspects of a touch should a court require it.

I am concerned, however, that we need to be clear what is supporting what, and avoid circular reasoning.
Which comes first, the determination of simultaneity or the individualisation?

Where I see the problem is when an examiner has some evidence of simultaneity in prints that do not stand alone, but not conclusively. He then conducts his comparison and finds that all the detail, in aggregate is, in agreement. It would be unsound to then conclude that the comparison supports the simultaneity and therefore, given this newly and incorrectly determined simultaneity, the prints can be individualised.

If the individualisation stands alone, without considering simultaneity, then it can support simultaneity.
If the simultaneity stands alone, without individualisation, then it can support individualisation.
Where neither determination stands alone, any individualisation (and indeed determination of simultaneity) is unsound.

This should all be covered in an appropriate training programme as recommended right at the start of the main body of the SWGFAST document but it is a pitfall of logic that I think should be highlighted.

Yesterday, I said:

Gerald Clough wrote:They also don't address the meaning of one kind of inconsistency. What if we are presented with a cluster of, say, four impressions that look for all the world like simultaneous impressions of four fingers on one hand? When we examine them, we find that the 1st, 2nd, and 3rd have detail consistent with the record but do not stand alone, and the 4th has clear detail not consistent with the record. (Throw an exclusion into examples 1.4.4 and 1.4.5, Figs. 8 & 9.) The 4th (or make it the 2nd or 3rd) is perfectly consistent in position to be simultaneous but can't be sourced to the record. Does that destroy the simultaneity conclusion?

As often happens, after sleeping on it, I think I answered my own question, and then David said it in a more ordered way, that if you're not solid on simultaneity, no aggregate of detail can support identification. The odd impression out in what otherwise would appear a simultaneous cluster killed the conclusion.

Which takes me back to what I think is one of the critical issues today, the interpretation of complex impressions and the limits of what can be done legitimately in leaping open areas. Using my example in which a cluster that otherwise gave every indication of being simultaneous contained one exclusion, consider the same cluster but with the excluded impression now having no detail. Same impression events, only that one didn't happen to be clear. This is essentially the same as Fig. 9 in the proposed standard. In Fig. 9, the leftmost impression of the three is used to support simultaneity, and that simultaneity is used to support the aggregation of the other two for identification. But all you really have are two impressions with detail consistent with the record.

That seems to me to be assuming too much. I have to agree with Coppock that it's a leap of faith. I wonder if we're not tending to what amounts to an overall lower standard by thinking of apparent simultaneity as having some special power. There are, of course, two somewhat different aspects of simultaneity. One is its use in support of an identification where no impression is identifiable by itself. The other is when simultaneity demonstrates the physical position of the hand on an instrument or surface and is used to show how it was manipulated, touched, or gripped. (Or, maybe they're not different, since each is a conclusion of simultaneity.) The real situations are those in which the aggregate is required for identification. In that case, we're really just back to the common problem of gappy impressions where we interpret across the gaps. And that comes back to the ultimate problem that, on one hand, we hold that any clear detail not in agreement with the record is exclusion, and on the other hand, we assume that no such non-agreeing detail would have appeared in the gaps, had they only been clearly impressed.

The answer is, I suppose, that the Q/Q threshold must be very, very high when dealing with breaks in continuity. And that's what simultaneous impressions are, discontinuity in a possible impression of a large area of skin. Perhaps it should be emphasized that the SWGFAST standard is not a lesson in simultaneous impressions. The examples are illustrative of the text, not to be taken as necessarily examples of what should be concluded by any examiner for those specific impressions. I look to Fig. 18 as a "simultaneous impression" in which simultaneity is questionable but appears to be used to justify the aggregate. I look to Fig. 19 as the use of an NV to support simultaneity when it doesn't seem to me that it's justified.* I just don't think some of the illustrations could be used to affect identifications with anything like the low tolerance required. We don't come to grief often, but when we do, it's often from overreaching. Gotta watch that.

* There are, on the same card, other impressions, clearly not simultaneous. So, are we just picking the ones that suit us, because they're consistent with simultaneity, and ignoring the others? Does the presence of numerous other impressions, aside from those that happen to be consistent with simultaneity, prevent a conclusion? The use of a simultaneous impression depends on each aggregate portion agreeing with the finger in the position reflected by the impression. Using any finger impression not absolutely concluded to be impressed in its correct position is no different from using the aggregate of randomly impressed finger portions in the aggregate, a situation that we see all the time and don't use.

David and Gerald,

Am I correct that you’re saying that this is a standard if-then statement (IF simultaneity is established THEN we can use the aggregate to do a comparison)? First we must establish that the ‘IF’ portion is true PRIOR to executing the ‘THEN’ portion. That would mean that we must determine simultaneousness PRIOR to doing a comparison. If simultaneity is established prior to doing a comparison then the statement in 2.3 (Simultaneity can be supported or refuted during the comparison, evaluation, or verification phase. If it is refuted then re-analysis shall occur) is illogical.

It’s sort of like saying, “IF Bob is a relative of Ann, THEN we can compare Bob’s DNA to an unidentified body to see if it might be Ann”. If we've established that they are relatives and we move on to the comparison process, then the comparison process shouldn't be able to refute or support the initial conclusion that Bob and Ann are relatives. If it did then it means that the original IF statement wasn't really ever established and the examiner shouldn't have moved onto the THEN statement. At this point, the entire process would be flawed.

I know I'm not explaining my thoughts very well but it seems that the two parts of the IF-THEN statement need to be kept separate and done in a linear fashion because if-then statements are not commutative.

Does that make sense? Am I understanding 2.3 correctly or am I misinterpreting something?

You've stated the IF-THEN correctly in the sense that, if it's done, it must be done that way. (But hold on that until the end of this post.) When we are dealing with the none-stand-alone aggregate case, using the fact that the less than sufficient to stand alone details happen to fit the presumed record prints is an error, since it presupposes they are parts of the friction ridge skin of a single person. In other words, they mean nothing unless they have a common source.

The problem with the DNA analogy is that Bob's DNA isn't presented piecemeal, so we can directly compare Bob's DNA to the unidentified to see if it's Ann. (Or likely to be Ann, since we can show them to share familial DNA but not show that it's specifically Ann without knowing more.) But yes, there's no point at all in trying to aggregate unless you are dead certain they are simultaneous.

What bothers me is that, as someone mentioned in passing, it's hard to say what is enough to declare simultaneity. Having a rich impression of most of the palm and multiple fingers all in consistent relationship in a situation in which it's reasonable that such an impression might be found is one thing. Having the tips of three or four fingers is another. Will we assume that the impressions were laid down with the fingers extended in anatomical position? Will we assume the individual conformed to our expectations in relative finger length? Do we demand a strongly likely sort of contact with the surface, or do we admit unusual or less likely grips or orientations? Am I justified in presuming that two fingers wide enough separated to leave space for a missing finger between them and comparing to, for instance, 2 and 4, or do I need some kind of impression between? At what point am I letting the detail support the notion of simultaneity? This is somewhat different from the problem of a single impression of one finger with a black band running through it. There, we can count and follow ridges and look for reasons for the gap. Here, we need only lift one finger to miss having that impression, and we can't follow anything from one portion of detail to another. Can we ever say with absolute certainty that four finger tip impressions, no matter how logically situated, are simultaneous?

It's kind of a funny area. We're making a determination that the impressions in a cluster all have a common individual human source before we see if we can identify the source. There are no natural laws, no science, that can confirm this in the way an identification is confirmed for a single stand-alone impression. It takes an awful lot to make a conclusion of simultaneity a scientific certainty. And if you can't get to that, no amount of agreement among aggregate fragments can get it for you.

NOTE 07/11/08 - IT'S BEEN POINTED OUT THAT I MISSREAD THE DRAFT STANDARD, EVEN IN M OWN QUOTING OF IT, SO, WITHOUT DELETING THE POORLY FOUNDED COMMENTS BELOW, I CAN SAY DISREGARD IT.

However, and it's a big however, that's my view. That's not the SWGFAST view as I read the standard. The proposed standard says:

2.1 Prior to comparison, an analysis of the known exemplars must be performed ensuring that all
impressions are in proper sequence and attributable to the same person.
2.2 For each friction ridge impression determined to be of value, the examiner should proceed to the
comparison phase.
2.3 Simultaneity can be supported or refuted during the comparison, evaluation, or verification phase.
If it is refuted then re-analysis shall occur.

How can you claim assurance in 2.1 and then admit that you can be found to be wrong in 2.3? If I admit I could be wrong about simultaneity, why am I going forward? Apparently, at least so far as logic has carried me, SWGFAST allows the fact that there is aggregate agreement with the record solidify the conclusion that they are simultaneous. That just seems to me to be playing loose and free with first principles and to be making the conclusion of simultaneity so convoluted, if not circular, that it's dangerous. And, if simultaneity is so weekly reasoned, the ultimate conclusion is fatally weak.

Perhaps someone can tell me if I'm reading SWGFAST wrongly. (Or worse, that they're reflecting current practice.)

Michelle: Yes I was saying it's am if-then situation and it was 2.3 that spurred me into writing.

I'm now grappling with the following scenario:

I have 2 latent prints. I conclude from my analysis that one print could stand alone for individualisation and the other cannot. I have some evidence of simutaneity but not conclusively.

I individualise the stand alone print and compare the other with the appropriate exemplar digit. I find all detail in agreement but, as said earlier this one does not stand alone. However with what I have now seen in comparison I "think" I have conclusive evidence of simultaneity.
Having simultaneity confirmed at this stage, can I now individualise the second latent print in aggregate with the first?

I'm not sure.

An interesting hypothetical, since it does not present the need to first be certain of simultaneity before making an identification. Maybe it's kind of related to the recent transitivity discussion. IF A is sourced from X (by direct comparison), AND IF A and B are of common source (by simultaneity), THEN B is sourced from X. The instant problem is, though, the question of simultaneity. Do you have it?

My feeling is that simultaneity must stand alone and must in most cases depend entirely upon logical positions of enough impressions with characteristics that are consistent with correct anatomical locations and deposited in an explainable way. I don't demand that solid information concluded from print detail be ignored in making this determination. In your example, for instance, you have a stand-alone latent that you can particularize to a specific finger. If it's the RI, then its reasonable to expect other marks consistent with fingers to the right of it. If, however, it was a RL, any marks to the right of it are not going to be simultaneous with it. But that's as far as that stand-alone gets you in concluding simultaneity, I think.

AND - BIG AND - In a private email, it's been pointed out to me that, with reference to earlier posts, I simply misread subsection 2.1 of the SWGFAST standard and failed to see that it addressed observation of the known exemplar. I suppose I was anticipating section 2 to address a sequence of process and missed the key point.