Duplicate Lifts

[Charles Parker]

I am reveiwing a case now that is kind of interesting and involves a duplicate lift.

The crime scene person (PC right) made a lift from a large staircase railing. The lift consists of the left ring and left middle fingers. There is ridge continuity all down the phalanges to the interdigital area below the left ring finger. So I have fingers, joints, and palm print on this lift.

They then made two separate (duplicate) lifts of just the fingers and the interdigital palm area. The palm area is the same shape, form and background as the palm area on the primary lift (a second lift of just the interdigital palm area).

Now they are documented first and second lift even though the second series of lifts are separate (fingers from palms) than the primary lift.

The LPE in conducting the latent print examination has identified the fingers on the primary lift which is contiguous all the way down to the interdigital palm.

The LPE has identified the palm of the secondary lift as the left palm and of course the fingers.

Now here is the rub. There are no palm prints availabe for this subject. The palm from the 1st lift since it is contiguous was used as the known print (after it was identified) as the exemplar to compare to the separate latent palm print of the secondary lift.

Would you use one part of a latent print which has been identified with a separate part as the known exemplar to identify a second latent print of which you had no known INKED exemplars?

I guess it could work?

[Danny Lamont]

Charles,

If the two partial palmprints on the two separate lifts share enough of the same friction ridge detail so that an individualization can be made, then by all means, yes, make the comparison. However, in such a case, I would also get Major Case Prints on the suspect; after which, I would then make another comparison on the two separate palmprints. I would do this to avoid any questions from the defense that may confuse the jury, as well as making the prosecutor's job that much easier. With the second comparison, you take that ability away from the defense. He will be left with very little leeway in questioning that identification. I would rather do some extra work on the comparison end to avoid the extra work in trying to explain the original comparison to the jury and have those questions raised by the defense. I have had cases in the past similar to the one you are talking about. This is exactly what I did, making the second comparison using Major Case Prints, and having no problems in court (if I did have to testify) using that second comparison. Yes, I mentioned the first comparison on direct, then told the jury what my next step was to insure that the two palmprints were indeed left by the subject's palm. This looks good for you to the jury; a very thorough latent examiner who takes his time to do the job correctly; taking no short-cuts. I hope that this answers your question, Charles.

[Charles Parker]

Danny I was not thinking along the lines of post arrest. I would have to say yes after he is arrested then you can MCP, palm prints, extra 10-prints etc taken.

I was thinking more along the lines of Pre-Arrest.

Is comparing one latent print with another latent print which has been identified with a known exemplar really cricket.

You already have the one ID on the subject why not write the report on the single ID and since you do not have a set of palm prints on file you include in your report that the latent print on item 3 is a palm print and that no comparison was conducted with John Doe as no palm print exemplars of John Doe currently exist in file. Then when they arrest him and you get the palm prints you complete an updated report or as some might call it a secondary examination report where the palm print was identified.

Apparently no one has a problem with using a latent print as the known exemplar to compare with a second latent print.

You got the one, why push the envelope for the second when you can wait for post-arrest to obtain the proper exemplars and make a proper comparison. You are more than likely to hit him on another piece anyway.

All I am saying is why push the envelope for two when you already have one in the hand?

[Ernie Hamm]

Charles,

There seems to be little difference between with your methodology of latent-to-latent and when the latent becomes the accepted exemplar for comparison to unknown record fingerprints obtained in post-mortem identification situations. This occurs when personal items of a supposed victim are processed for latent prints and these are "assumed" to represent the record prints of a victim to validate an identification. PMI does not get the scrutiny of criminal identifications, but similar purposes are being served.

In answer to your question, Yes. I believe if you are confident in the latent's quality and quantity, it can be used as a comparative standard. In fact, you may find that has been a frequent (but probably undocumented) approach when an identified latent print has better overall quality and quantity than the record and multiple comparisons are needed.

However, as you stated, why get involved in the argument when you already have your answer and anything else is gravy you can get later.

[Charles Parker]

Ernie, you brought up a good point on doing it in PMI's and as you say there may be a little difference but the difference would be someone arrested vs family being notified (not counting getting the M.E. off your back). I think a lot of labs and ID units have done the PMI with latent prints at one time or another. I know we have.

In answer to your question, Yes. I believe if you are confident in the latent's quality and quantity, it can be used as a comparative standard.

I think confident and how well you can explain it as Danny pointed out is the key. Not something I would recommend to the new examiner and a position that should be considered for awhile. But for my part I have the one, I think I will just wait a while for the second one to come to me.

In fact, you may find that has been a frequent (but probably undocumented) approach when an identified latent print has better overall quality and quantity than the record and multiple comparisons are needed.

Very good----I cannot say I have, I cannot say I haven't, all I can do is take the fifth. Good point. If you were doing a case review and saw that or had a good idea that has occurred what would the reviewer do?

Let us take it another step. Will it be the same in two cases. One has the finger to palm continuity. The ID is made on the finger and no palm print exemplars are available. You go to the second case look and all you have is a palm print that is the same as case number 1.
Does our principle says yes to just a single case but no to multiple cases. If you do it for one, you got to do it for two, or three, etc.
I am back to my principle---I have one in the hand, the second one will come to me.

Or to change it up. My one in the hand is off the exterior of an auto and is not going to buy me beans in the evening, but the second one is off the inside of residential burglary. Well Chuckie Boy what are you going to do with your prinicples now?

Then I might resort to the Danny and Ernie reasoning approach. But I must say I would turn heaven and earth over trying to find a set of palm prints on that boy for the second case.

These are all hypotheticals and my intention is just to get some readers to think about them and that just because our first inclination might be to do it this way, perhaps a little thought into the problem and how you would articulate to get yourself out of the problem would be in order.

Some people might call it mind games that I am playing, but I look at it as trying to get maybe some examiners to Stop, Think, Reason, and then Act. Some of the problems we get ourselves into, just might disappear.

I still plead the fifth on Ernies' second paragraph. Anyone else want to plead the fifth with me or just have a fifth?

[Gerald Clough]

Okay, but it's good mind games. The situation of using the vehicle exterior patent array to identify the interior latent is no different from using the finger and palm contiguous print in one case to identify a finger-only latent in another. It's all just evidence, and it's subject to expert interpretation and the best use possible. I say no difference, because we're talking about latent print examination. There only seems to be a difference when we think about proximity and think it's important that the source of the exterior vehicle latent was around the vehicle. We are then implying that it's more likely to be the same source as the interior latent, a fatally poor consideration in the examination.

There's only one issue. That's whether or not the impression of finger and palm are truly contiguous, a single impression. If it is, and you can demonstrate it to full confidence, it's a fact, and it identifies the finger-only latent. You're not guessing. You're not reaching. If you have doubt, you can't use it. What's the real question?

Are we considering what to do if we need it to make the arrest and it's the only way? Are we saying our standard changes and our tolerance increases at need? Conversely, are we saying our ability to identify and our tolerance is reduced with lack of need, that we can only do something if it's important? Why would we consider the need? It's an important question. We can't pretend appropriate caution and wait for a record palm just because we can afford to wait and then claim, with exactly similar evidence, that we need no such caution and can make the identification with confidence when we need it badly in another case. If you can't do it in the bicycle theft, you can't do it in the murder. If you can do it in the murder, you can do it in the bike theft. The only question is can you do it.

I just cannot see any valid justification for waiting to see if I can find a palm record some day, because nothing that matters is going to change between now and whenever I give up searching for palms. Not the evidence. Not my abilities. Not my tolerance (I should hope not.). This is not to say I wouldn't wait when I knew a palm record was on the way in the mail, because that's just using the best available exemplar. We're talking about something else.

[Kasey Wertheim]

Neat thread.

One side-comment on the scenario prior to my thoughts on the heart of the issue. Your scenario involves duplicate lifts of the same impression. If there were sufficient quality and quantity of evidence to support a duplicate lift of the same impression, I would report it as such and not compare it. In other words, for your scenario I would report the first lift bearing all of the prints as Impression 1, and be done.

Setting that aside and assuming 2 impressions, then I agree with Gerald - it's perfectly legitimate with sufficient Q/Q to individualize one to the other. A basic algebra proof we all learn in grade school is that when A=B and B=C, that A must equal C. This is no differet - if L-1 = John Doe, and L-2 = L-1, then L-2 must equal John Doe. All standards for individualization apply to both comparisons to achieve the third, so if there is doubt on one of the identifications, then the proof doesn't apply.

I also agree with the real-world aspect of not confusing the jury. Once you have John Doe, what's the harm in simplifying the facts for the person who really matters - the juror (kudos to Ron Smith for ingraining that in my mind 'growing up'.)

Like I said, neat thread!

-Kasey

[sharon cook]

I think that the statement If A=B, and B=C, then A=C is a fallacy of logic, but I can't find the proper name or an example. I logged on to a website called "Logical Fallicies" but it is LOADED with fallacies! Can someone help me out?

[Kasey Wertheim]

I'll help you out.

I googled "if a=b and b=c" and found the following:

http://en.wikipedia.org/wiki/Equality_(mathematics)

It defines the proof as the "Transitive property" because equality transfers from a to c by way of b.

Encarta has a good explanation of the principle:

http://encarta.msn.com/encyclopedia_701 ... tics).html

Hope this helps you out.

-Kasey

[Gerald Clough]

Transitivity is a property of equality and implication. If A=B, and B=C, then A=C. (In math, we have to qualify that A and B are Real numbers. It's not true for floating point numbers, for instance.) For implication, "If A implies B, and B implies C, A implies C." Not all relations are transitive. If A is the mother of B, and B is the mother of C, A cannot be the mother of C. Motherhood isn't transitive. As we well know, friendship is also not transitive. More importantly, "similarity" is not transitive, although this doesn't stop people from trying it. It's popular among attorneys.

A fallacy of transitive implication, usually called Transitive Hypothetical Syllogism, isn't a problem with the transitive property of implication but with the truth of one or more of the relations. If A implies B isn't always true, A can't imply C. Our commonly imprecise everyday language often substitutes "equals" when we mean "implies." "Sunny summer weather equals higher water usage." We mean implies. Weather and water usage cannot be said to have the same value. Weather cannot be high, and water usage cannot be sunny.

In our present case, we're saying:

(Latent1 matches Record(S)) implies S is the source. (Latent2 matches Latent1) implies they have the same source. Therefore, S is the source of Latent2.

No fallacy, unless one or both of our matches were false.

[mary ellen holmberg]

When we have a slew of pawn tickets and one of the thumbprints is inked higher than the knowns, we identify that pawn ticket to a pawn ticket that was identified to the known prints (which were not rolled high enough). I don't know if that sounds clear, but if you have ever done a handful of pawn tickets, you know what I am talking about!

[Charles Parker]

Well it looks like "old Chuckie-Boy" has been outvoted and to say it nicely "Out Gunned". I would have to say there is a consensus and that means it is time to take this concept and put it into a principle. I was going to say the "Principle of Continunity" but I like a word that Kasey and Gerald used: Transitivity.

The Principle of Transitivity states: Friction Ridge Detail once individulized may be used as further known exemplars [A=B, B=C, A=C]. (Any wordsmiths can jump in here and clean up or add to the statement)

ie. If a part of a friction ridge image has been individulized the remaining part may be used as a known exemplar provided that continunity is present.

The Principle of Transitivity can be used when current exemplars are substandard or non-existent.

Q1--Would the "Principle of Transitivity" be applied in the following scenario. You have two latent prints that are approaching borderline Q&Q. Any re-examination would take some considerable time. You arrive at court and you have the two latent prints and the original exemplar that you used in your examination. You obtain the inked prints of the subject on trial. Instead of trying to do a re-examination of the two latent prints with the now new exemplars you compare the new exemplars with the original exemplars and if they are from the same person the "Principle of Transitivity" could be used.

A= Latent Prints
B= Original Exemplars
C= New Exemplars

If the latent prints (A) equals the Original Exemplars (B) and the Original Exemplars (B) equal the New Exemplars (C) then the Latent Prints (A) equals the New Exemplars (C).

Any thoughts or ideas on the "Principle of Transitivity"??????

Thanks go to Danny, Ernie, Kasey, Gerald and Mary Ellen and the others that e-mailed me.