Fingerprint Evidence vs Eyewitness Evidence

[Simon Bunter]

Below is a link to an article about a recent fingerprint cases I gave evidence in at Crown Court. It basically came down to 'Fingerprint Evidence vs Eyewitness Evidence'; only one could be correct.

[Steve Everist]

It basically came down to 'Fingerprint Evidence vs Eyewitness Evidence'; only one could be correct.

I don't see this as the case at all.

There are three different eyewitness conclusions, relative to the palm print:

Contrary to the allegation that the offender jumped over the bar by placing one hand on it, two eyewitnesses said the offender ran around the side and went through the bar hatch

One eyewitness reported that the offender had touched the bar with his right hand whilst trying to jump over it: it was the defendant’s left palm print that had been recovered

Eyewitness evidence described the offender as wearing “fingerless gloves”, something that the police expert was unaware of at the time of the initial fingerprint evidence, but later dismissed as being irrelevant

The first and second couldn't both be correct, and it's possible that none of them are.

It doesn't sound like there's any disagreement as to the whether or not the palm print belonged to the defendant(?) either. But should the defendant have even been a defendant?

I think the issue, regarding the palm print, is the description of it being fragile vs. robust (how did you test it for a 'robust contaminant', and what does that mean?) and the conditions by which the palm print was placed on the bar. But I don't think it's 'Fingerprint Evidence vs Eyewitness Evidence.' The police and independent experts may have overstated how fragile the print was as you may have overstated how robust it was. A print deposited in this location may or may not survive cleaning. Ultimately, the print was a record of contact between a person and the bar. If the only evidence the prosecution has is a print on a bar counter top in a location that it could have been placed by anyone standing or sitting at the bar, and that there were three different versions of eyewitness testimony that don't corroborate the palm print, I wonder how it even made it to trial.

[Simon Bunter]

Hi Steve.

You make some really good points, I'll try to elaborate a little.

The prosecution relied on the evidence of one of the eye witnesses who originally was adamant that the offender jumped over the bar by placing one hand on it. This initially appeared to be consistent with the palm print evidence. The same witness later said that the offender tried to jump over the bar (but could not) and in doing so placed their right hand on the bar. When this altered version was considered along with the evidence from the other eye witnesses (i.e. the offender was wearing gloves and looked visibly different to the defendant), the eye witness evidence overall was inconsistent with the palm print being placed by the offender.

There was no disagreement regarding the donor of the palm mark, although interestingly police fingerprint officers had erreoneously excluded the defendant as the donor four times.

With regards to fragile vs robust; it was not possible to carry out a robustness test or establish what the mark was formed in. My point was that the mark bore visual indicators suggesting it was not a 'normal' mark in sweat, i.e. it was likely formed in something else (a contaminant). It was not possible, however, to determine whether that contaminant was fragile or robust. If robust, it remained possible that the mark could have survived the described cleaning.

I think you sum up the point of the article nicely when you say "there were three different versions of eyewitness testimony that don't corroborate the palm print... should the defendant have ever been the defendant?" I agree. I think the only reason it reached a jury verdict is due to the police fingerprint officer's insistence that the mark was fragile and would not have survived the cleaning.

This leads me to my overall thoughts about this case; as the palm print evidence did not fit the eye witness accounts, I got the impression (no pun intended) that the police fingerprint officer and the other independent fingerprint expert had basically assumed that the eye witness evidence must be wrong. Hence the 'Beware the Power of Palm Prints' title.

[josher89]

I just have to throw this in here.

Our lab has these black chemically-resistant countertops that are like a heavily compressed resin of some sort. I had to drill through it once and burned up my bit; they're tough cookies! Anyway, I touch that counter all of the time with my bare hands and I am always leaving my prints behind. I've sprayed down that area, wiped it, and my prints are still there. I've had my co-workers come watch and they think it's a little weird that my prints are still there, even after cleaning. I will try and get a video of it to demonstrate. But it happens to theirs as well so I'm not some sort of super secretor or anything.

My point is, we should not be lending any sort of determination of fragility or robustness of a print based on what we think should happen when it's wiped/cleaned.

[NRivera]

... we should not be lending any sort of determination of fragility or robustness of a print based on what we think should happen when it's wiped/cleaned.

This, along with any implication as to the circumstances or time line under which the print was deposited.

[Simon Bunter]

I've worked on several previous cases where it's been possible to establish that the marks had been placed for several years before the crime. This was relatively easy to demonstrate, as the marks were still present when I attended the scene several months/years after the crime. This allowed me to test how robust/permanent the marks were.

In this case, however, the palm mark on the bar was not present when I attended the scene. This demonstrated that it was not permament but did this mean it was not robust? Essentially, the palm mark would have had to have been robust enough to survive the cleaning regime prior to the crime but not robust to survive whatever cleaning had taken place since. One plausible explanation for this was that the CSI explained it was police procedure to remove any marks they found at a crime scene before leaving the premises. Once the palm mark had been photographed by the police photographer it would seem that there was a concerted effort by police personnel to remove it.

Just to add a little more flavour to this case; the robbery occurred in 2012 and the defendant was excluded as a donor of the palm mark FOUR times before he was eventually identified in 2018...

[josher89]

If you're referring to the prints that were deposited in paint years before the crime occurred and were still visible after the crime occurred then yes, you are correct that their robustness was easy to demonstrate. I'm speaking of a latent print, not a plastic or patent print. One should not make any assumptions about its robustness unless you have prior knowledge (maybe that would be considered bias?) about how the print was deposited or had visual documentation of its deposition.

I believe it is a mischaracterization of print robustness when an example of a plastic print in paint is being used to offer that conclusion.

As with most science, it is based on observation. What we can observe, with multiple examples and especially over time, lends to our ability to produce reliable conclusions. It would be unfair for me to leave a print in fresh paint then reexamine it years later and say all prints are robust because I can see this one years after deposition. Each print needs to be taken on its own.

As a former CSI, can we opine that a prints looks 'fresh' because of how easy the powder sticks to it? Of course; and I did (never in a legal setting). But can we prove it? Not unless we were there when it was deposited. It shouldn't matter if there was a clean-up attempt in between time of deposition and discovery; we just heard that those attempts don't always wipe away the deposition matrix.

[Pat A. Wertheim]

I was retained by a public defender in San Diego a dozen or so years ago to review the fingerprint evidence against his client. The crime was "attempted burglary." The situation was that a woman was asleep in bed when she was awakened about midnight by the sound of a bedroom window being slid open. She sat up and saw a man at her window. She got up and went to the window as the man turned to leave. She saw him a few hundred feet away under a street light as he turned and looked at her while walking away. She called police who processed the window and recovered a single latent print. It was searched through AFIS and hit. The person was arrested.

When I examined the lift, there was no question it was the client's fingerprint, the far outside edge of his right thumb the way it would be impressed if the whole hand had been placed on a flat surface. But the lift had some unusual details. First, there were many tiny stria that trended in the same direction, but were not exactly parallel. Second, there was a plethora of tiny round specks reminiscent of water droplets, but very small and showing no directionality as one would expect to see on a vertical window pane. Third, the side of the right thumb was reported to be the only ridge detail on the window. There was no palm or other fingers as one might expect if the outside edge of the right thumb had touched simultaneously with the rest of the hand.

I flew to San Diego to meet the attorney. I told him I needed to visit the scene to resolve some issues with the latent print lift. The "attempted burglary" had occurred in February. It was the following September when I visited the scene, seven months after the alleged offense. The woman who had called the police showed us the window. I removed the screen, re-powdered the window, and -- SURPRISE!!! -- I pulled up a second lift of the same fingerprint that was on the police lift! Seven months on the exterior side of the window pane, exposed to the elements and previously powdered and lifted. The police evidence was absolutely genuine.

It turns out that the stria in the original lift were due to old tape that was breaking down. The patrol officer who lifted the print carried a tackle-box fingerprint kit in his trunk, where everything routinely baked in the hot sun. The solid presence of very tiny water droplets was due to a high pressure sprinkler head directly below the window spraying upward and being atomized by the window screen. As for the robustness of the print, one can only speculate on the residue on the client's fingers at the time he slid the window open.

After re-powdering that latent print on an exterior window surface seven months after the first lift, with high-pressure sprinkler spray hitting the window screen and drenching the window regularly in the intervening months, not to mention the other outside environmental conditions, I have been very loathe to speculate on the age of a latent print or the expected delicateness of a latent print. Sometimes, a latent print can be amazingly robust in its staying power.

POST SCRIPT: It was eventually discovered that the client had been seeing the complainant's daughter on the sly. The daughter had previously used the bedroom in question, but her mother had switched rooms with her a day or two before the "attempted burglary." Prior to that, the client would slide open the window and whisper to the girl, who would then go outside to see him. He had showed up unexpectedly on the night in question, but the girl had not warned him of the switched bedrooms. The client was trying to protect the daughter, his girlfriend, by not admitting their relationship. Once the daughter admitted the relationship to her mother, all charges were dropped against the client.

[Ernie Hamm]

This discussion about “freshness” of a latent print is not new. Over the years there have been numerous articles published (Pat, Kasey wrote one in 2003!!) in the Journal of Forensic Identification, Identification Canada, Fingerprint Whorld, et al on problems trying to determine the age of a latent print as well as recounting controlled experiments to demonstrate it is a problem. I even heard a story of an unnamed FBI latent print examiner that early in his career placed a latent on the underside of a desk calendar holder and, upon his retirement many, many years later, powdered the area and developed his ‘fresh’ latent print. No citation or names, just an anecdotal account.

[josher89]

This is an article that was published by Mr. Bunter where he conducted print processing using various matrices and developed those prints over time. Based on the appearance of the included images, one cannot opine as to when the prints were deposited but can objectively see that the older the print (from deposition to development), the poorer the quality of the impression.

The matrices that were used that included hydrophobic substances persisted longer than those of a hydrophilic nature. Which makes sense; oil and water don't mix all that well. Since most of the moisture that is present in the environment is water, it stands to reason that oily substances (or in this case, oily deposition of ridge detail), will prevail much longer than water-soluble substances.

SBCSEyeFPLongevityPaper.pdf

To follow up with my previous post, another article published by Mr. Bunter points to a

3D impression in a robust substance which was then ‘cast’ by the lift

as the reason for the persistence of a print. Again, plastic impressions should not count as a measure of longevity or robustness of a latent print.

[josher89]

before.jpg

after.jpg

Kinda hard to capture when you're not there but this is the before and after of my hand print on the lab countertop. I used 10% bleach to clean up the area after I touched it. The ridges were really easy to see when the area was still wet but faded slightly after it dried. (referencing my earlier post on this thread)

[Simon Bunter]

Hi. Those are some great examples of fingerprints persisting. I'll just clarify a couple of comments made by josher89.

I'm speaking of a latent print, not a plastic or patent print. One should not make any assumptions about its robustness...

I'm not quite sure what you mean by a "plastic" print. None of the prints I referred to earlier have been formed in plastic, although some have been patent and some have been permanent. The palm mark on the bar in this case was patent in that the CSI reported finding it without the need for development powders. It was not permanent, however, as it was not present when I examined the bar over six years later. I have not made any assumptions about this palm print; that was done by the prosecution expert who assumed that the print would be fragile enough to be removed by the described cleaning. He assumed it would be fragile because it "has the hallmarks of a more fragile mark". My entire point was that we should not make assumptions about what the mark is formed in or how robust or fragile it is.

It would be unfair for me to leave a print in fresh paint then reexamine it years later and say all prints are robust because I can see this one years after deposition. Each print needs to be taken on its own.

Of course I agree with this and in no way whatsoever was I saying that all prints are robust because one print in paint survived several years. What I am saying is that the palm mark on the bar in this case looked visually different to 'normal marks' suggesting it may have been formed in a substance other than sweat. If it was formed in something other than sweat then that substance could be fragile (like sweat) or robust. If it was formed in something robust then the palm mark could potentially have survived the described cleaning.

Although it sounds like we are disagreeing, I think josher89 and I are in agreement with a lot of these issues.

Long story short; regarding the eye witness evidence for the palm mark on the bar case:

If the offender was wearing gloves… the palm print must have survived the cleaning
If the offender did not touch the counter (or only touched it with his right hand)... the palm print must have survived the cleaning
If the offender was slim build… the palm print must have survived the cleaning