CLPEX Chat Board

"I have no knowledge of any fingerprint expert ever examining a scene mark using a plain impression....I worked for 37 years in bureaux comparing hundreds of thousands of marks and always used a rolled impression."

Discuss.

Your quote misrepresents the background to that statement. As you and many others are aware, Peter Swann found it very unusual that Pat Wertheim took 80 - 100 plain impressions of Shirley McKie's left thumbprint ONLY for comparision against Y7 and NONE rolled.

I'm pretty sure you knew that's what he meant.

Discuss.

On the contrary...

I may have failed to present the background to this quote, but I misrepresented nothing.

For the sake of competeness, however, I shall cite the full paragraph.

"I was fascinated to receive, over the internet, the marks of the scene imprint and Shirley McKie's left thumb, which were circulated by the Americans. I was appalled by what I saw. For instance, the fingerprint from the door had a scrape mark from the bottom left to the middle right. I know that the SCRO mark did not have that and I am also aware that Peter Swann has a pretty good photograph of this difficult mark that does not have that scrape mark. I wanted to know, first of all, where that scrape mark came from, given that it was not there when the mark was photographed by the SCRO. Also, the fingerprint of Shirley McKie was a plain impression. I have no knowledge of any fingerprint expert ever examining a scene mark using a plain impression. The system started in 1901 and, since then, rolled impressions showing 100 per cent of the detail have been used. Plain impressions show only about 50 per cent of the detail—I might say, grudgingly, that they can show as much as 60 per cent or 70 per cent of the detail. Throughout the world, millions and millions of computer programmes are used and every one is based on

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the use of a rolled impression. I worked for 37 years in bureaux comparing hundreds of thousands of marks and always used a rolled impression. Why did Wertheim and his associates send a plain impression of Shirley McKie's thumbprint? That was my big problem. I decided at that point to take an interest in this case."

Nowhere in his openning statement does Mr Berry make any comment on the number of impressions taken by PW. He specifically states that he is commenting on a single plain impression that he received.

Oh and by the way...

If you misattributed my openning quote to Peter Swann then you really should be more careful in your research.

Here, let me help you.

http://www.scottish.parliament.uk/busin ... 6-2602.htm

Ok, NG, it did occur to me as soon as I clicked 'submit' that I had remembered wrongly who made the quote. By that time, of course it was too late.

I would say that my comments to a certain extent still apply. John Berry is clearly in agreement with Peter Swann in relation to Pat Wertheim taking plain impressions ONLY and NONE rolled. He may not have mentioned during his discussion part of the hearing an exact number, however I would hazard a guess, that he was more than aware of how many plain impression forms Pat Wertheim took from Shirley McKie.

With your disclosure of a now larger piece of text, it changes the context of your post/John Berry's statement completely.

Now discuss.

On forum use... You can always edit or even delete your own messages on this forum. Check the buttons at the top right of your posts next to the "Quote" button.

Unfortunately we do not have what Mr Berry meant to say, or what he was thinking at the time. The public record has him saying that in 37 years he never used a plain impression in comparison with a latent print.

Keep discussing.

PS My disclosure of the full paragraph does not change the context of the quote it simply adds context which was originally missing.

Well, I guess I’m not one of the uber-examiners that frequent this forum because I often use plain or flat impressions to make comparisons. It is true that the “flats” may not have the same quantity of detail as rolled impressions, especially delta areas. However, I have often had to move to the flat impression because the rolled impression was distorted or unusable due to over inking or movement.

Let’s think logically about this. A rolled impression does cover more of the friction ridge detail present on the last joint of a finger. But it does not capture 100% of the detail and never will, even with a nail to nail roll. The detail at the finger tip is not captured with a rolled impression, but it is possible to capture fingertip detail, or at least more of it with a flat impression. Again, think of the recording process.

As far as having an accurate re-creation of ridge detail to compare to latent prints, think about how people handle and touch things. When you pick up a glass, do your fingers roll over its surface or is there contact consistent with the type of contact used to record a flat impression?

Haven’t any of you ever used the plain impressions because you were looking for lower joint detail? That detail does not reproduce in the rolled impressions. (At least not to any significant amount)

Whenever we tread the ice with terms like “always,” “never,” and “100%” we will soon find ourselves in for a very cold dunking. Those terms can only be used when their full meaning is intended.

NG, I have observed that your posts appear to be dedicated to finding flaws and holes in witness statements of Peter Swann and John Berry. Or could I extend that to anyone that has identified Y7 as Shirley McKie? Unless of course you have already trawled through all the pro-ident experts statements and found them to be water tight.

So let's get back to John Berry. I will offer a point of view to continue this thread if you are sincere that you wish to open your post/quote for discussion.

There is nothing that I find unusual in the essence of what John Berry had to say about the use of plain impressions. He is correct to state that plain impressions reveal 50% or at best 70% of the necessary detail in a print. For this reason I DO find it unusual that 80 - 100 plain impression prints were taken by PW for comparison against Y7. My choice of fingerprint form would most definately have plain AND rolled prints taken. The more data available, the more accurate the comparison and ultimately, of course, the more accurate the result.

Ok, this thread is turning into a playground. NL I apologise.

Let's return to the subject matter.

Plain and rolled. My choice of fingerprint form would most definately have plain AND rolled prints taken. The more data available, the more accurate the comparison and ultimately, of course, the more accurate the result.

Apology accepted SofA.

I beleive we do have a concensus here. When searching for an unknown latent it is best to have both plain and rolled inpressions.

May I seek further agreement? I would go so far as to say it is good to have many different forms available just in case the area you are looking for is missing from any one.

Of course the rolled impressions are the best starting point for your search because they display the greater proportion of ridge detail. But once you have found your latent it may be that the distortion inherent in a rolled impression will make it easier to compare it with the plain; if the plain covers the right area.

I find the notion of always using rolled impressions a strange thing.
Start with the rolled, for sure. But for ease of comparison use the one that most closely resembles your latent.
Isn't that what PW was attempting to do when he had a latent of supposed known origin?
Was it the fact that he could not reproduce this latent using Shirley's left thumb that resulted in him having to take so many prints?

Just wondered if anyone noticed that Monday's session SCRO witnesses did not seem to have the same difficulty over the top of the print which had been emphasised by the original SCRO 4 as the elim forms as being of poor quality for comparison of that part yet SCRO members would have examined the same elim prints

NL - latents are CHANCE impressions. I won't do the math, but would go out on a limb to say that a crime scene mark, or any mark at all would be close to impossible if not impossible to reproduce.

If I had a case passed to me for examination containing a photographed impression of a poor quality latent showing signs of distortion I would be less than happy if 80 - 100 plain impression only prints were enclosed for comparison. That's if it was a negative result of course. The reason being, I couldn't be satisfied that I had made the best comparison I could have without having all the data available to me. Plain impressions are only half the data.I'd feel exactly the same way about palm print forms if 80 - 100 half palm prints were taken for comparison against a poor quality palm mark. Even a good quality palm mark for that matter. There isn't a fingerprint expert out there that hasn't been a tad irked when the palm print form (especially if it's the only form on file) contains half a palm. Can you imagine 100 of them? Grrrr. Why should it be any different for digits?

Absolutely SofA, When looking for a latent of unknown origin you want to have all the ridge detail of your suspect recorded in the best quality. Nothing narks me more than having a palm print to identify and the investigator hasn't even taken palm prints from his suspect.

However, do you see the difference when you have a reported source of the latent (finger x of suspect y) and you know from your analysis of that latent that it is a piece of the tip of that finger, using a plain impression of that finger would be best.
If you have the chance to take prints from the suspect yourself, knowing which part of which finger you need to compare don't you record that area several times (as well as everything else at least once) just to be sure of having the best possible material to work with?

nigeus lowlef wrote:"I have no knowledge of any fingerprint expert ever examining a scene mark using a plain impression....I worked for 37 years in bureaux comparing hundreds of thousands of marks and always used a rolled impression."

Discuss.

Since this is what we were asked to discuss, I’ll jump back to it directly.

I’ve *only* been doing latent print comparisons for eight years, but I’ve done many comparisons of flat/plain known exemplars to latent prints.

Many of the elimination prints that our officers take in the field are not only flat impressions; they’re not even done with ink! Since our officers don’t have portable eliminations kits, they often have the victims moisturize their fingers and lay them flat on a latent lift backing card (similar to plain impressions on a 10-Print card). Then they magna-powder the card and protect it with tape. It’s not ideal, but it’s a lot better than nothing. One of our suburban cities often does a full palm of victims on a sheet of paper, and then powders it. Once again it isn’t ideal, but the worst case is that we have to call it inconclusive and request better exemplars.

Our palm cards are taken as flat impressions. Even the ones “rolled” using a tube are done so to work with the hand’s natural curvature – to create a flat impression. In fact those rolled in this manner appear more distorted when laid next to palms taken by laying the hand flat on the card. Major Case Prints (or CFRE’s) often include rolled and flat impressions together. The flat impressions are there to get those areas not reproduced by rolling.

I’ve even had officers send in processed latents to be used for a comparison when they had a known suspect handle an item.

The point is that I don’t necessarily care if it’s flat or rolled – only that it contains the ridge detail necessary to complete my examination.

Regarding the flat impressions that Pat W took from Shirley. The only question in my mind is whether or not he took the other nine fingers. To truly exclude her from the mark, you’d need to have the rest of the fingers for comparison. Otherwise all that could be excluded is her left thumb.

Steve --- I took a full set of rolled impressions and plain impressions, as you would expect. And as you questioned, yes, I did exclude the other nine fingers, as well. But the latent print was represented as having been identified to Shirley McKie's left thumb and it was clearly her left thumb print on their court charts, so that is where I concentrated my efforts. Why did I take so many plain impressions to work with? Several reasons. First, to duplicate as closely as possible the direction and pressure represented in the touch that produced the latent -- to compare "like to like," if you will. Second, because I was on vacation with Dave Grieve and David Ashbaugh, I took extra inked impressions to give to them. I gave each of them photographs of the latent and sheets of inked prints but never told them my conclusion. They thought I was responding to a request to investigate fingerprint forgery, not erroneous identification, and I let them keep that mistaken thought in order not to be biased by my conclusion that the identification itself was erroneous. David Ashbaugh chose not to get involved at that stage, but Dave Grieve met with Shirley McKie's lawyers several days later and confirmed all of my conclusions without knowing anything except what he could learn from photographs of the latent and original inked fingerprints (mostly plain impressions). He and I never even discussed the case until after the trial.

The SCRO used a plain impression in their first court chart, #152 I believe. But they used rolled impressions in #180 and #189, both of which had the V-smudge at the tip associated with rolled impressions which had the effect of negating the blatent dissimilarities there. Of course, they cropped off the tip anyway, so it didn't matter.

We work with rolled impressions most of the time because that is what we have in our files. But when a latent print examiner gets a chance to review the latent prints first, then take the inked prints personally for comparison, I would hope that every true "expert" would give some thought to how the latent print was deposited and take some of the inked prints accordingly.