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Monday, March 13, 2006

The purpose of the Detail is to help keep you informed of the current state of affairs in the latent print community, to provide an avenue to circulate original fingerprint-related articles, and to announce important events as they happen in our field.
Breaking NEWz you can UzE...
compiled by Jon Stimac

Fingerprint Experts Boycott Conference over McKie Affair Ė SUNDAY HERALD, UK - March 12, 2006 fingerprint conference to be held in Scotland this week will be boycotted...

FBI Error a `watershed' in Fingerprinting Ė CHICAGO TRIBUNE, IL - March 12, 2006 ...FBI experts mistakenly matched fingerprints on a bag of detonators in Madrid...

Defendant Insists Fingerprints are Wrong Ė  RECORD COURIER, NV - March 12, 2006 ...confronted with matching fingerprints, defendant continued to insist that he is not a suspect...

Rape Verdict Hangs on Lone Fingerprint Ė  MIAMI HERALD, FL - March 10, 2006 ...jury will begin deliberations in the kidnapping and rape of a toddler...

Recent CLPEX Posting Activity
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Moderated by Steve Everist

miss shirley mckie
thedelightfulmissfabulous 1618 Mon Mar 13, 2006 1:47 am

Processing Cigarettes
M Semler 100 Sat Mar 11, 2006 6:12 pm

The V in ACE-V?
Mark Mills 2347 Sat Mar 11, 2006 12:07 am

US DOJ OIG Mayfield report
John Vanderkolk 96 Fri Mar 10, 2006 11:44 pm

Dr. Dror's interview on BBC - fingerprint reliability
Alice Maceo 919 Fri Mar 10, 2006 9:17 am

CSI Volunteers to do forensic work (Denver)
Shaheen 1569 Thu Mar 09, 2006 8:24 pm

"FBI ordered McKie case swept under carpet"-The Sc
Patrick Warrick 324 Wed Mar 08, 2006 9:48 pm

g. 248 Mon Mar 06, 2006 11:56 pm

redlion62 263 Mon Mar 06, 2006 9:35 pm


No major updates on the website this week.


Last week

we looked at an article by the late Carey Chapman on the history of the IAI.

This week

we look at the transcripts from a recent BBC interview of Dr. Itiel Dror, a UK researcher looking into context bias in latent print examination.

What kind of errors can fingerprint experts make?

What does that mean in terms of the reliability of fingerprint identification?  

Dr. Dror was interviewed about these issues by the BBC in February 2006 in light of the McKie case.  For more information, see:

Below is an edited transcript of the interview (if you want to view the interview Ďliveí on-line, then go to

Interviewer: Dr. Itiel Dror of Southampton University conducted experiments with experienced fingerprint experts.  Four out of five of them were found to contradict their own earlier decisions in certain circumstances.  This evening Dr. Dror came in to our Southampton studio and I asked him if his study proved that it is possible to make an honest and genuine mistake.

Dr. Itiel Dror:
That is correct, and itís more than that, Iíve done a few studies and itís not only that you can make an honest mistake and be genuine, but in the study that we have done, we took fingerprints from real criminal cases and presented them again to the same experts but provided a different context. In the different context the experts made different and contradictory decisions to the one they made earlier.  So itís not that different experts have different criteria to decide if itís an identification or not, but the same expert in a different context makes different decisions on the same fingerprint.

Interviewer: Yes, in this case what you did, was that you took fingerprints which these experts had previously identified correctly, but then five years later gave them the same fingerprints and strongly suggested to them that they were misidentifications, right?

Dr. Itiel Dror: Correct, in one study I did strongly suggest to them, but in another study I only slightly suggested to them that it is a misidentification  (when it was in fact an identification) or vice-versa (i.e., that it was an identification when in fact it was not). The context manipulated their expectation and affected how they judged the fingerprints. It didnít matter that the same fingerprints were judged by them differently in the past.

Interviewer: Youíve got a simple way to show the sort of thing youíre getting at.

Dr. Itiel Dror: Yes, we have examples where the context can affect what you see.  If you look at the numbers here youíre going to see 12, 13 and 14:



But if I show you this diagram, you will see the letters A, B and C:



In fact the information I showed you is exactly the same, and you interpreted the middle information as the number 13, or as the letter B, depending on the context:



This example shows you how a perceptual context can affect how you perceive information. However, we do not only have such perceptual context, we also have higher cognitive expectations and context which affect the mind. The mind is not a camera; itís not a passive machine.  So the higher cognitive context, what you expect to see, what you hope to see, what other people see, etc.,  affects what you actually see and that may cause a lot of distortions in your perception and evaluation of information.

Interviewer: Right, so the point would be that in a context where you have already been led to believe that a fingerprint has been misidentified, you are seeing it as a misidentification is almost analogous to what we saw there, where the statements ĎI saw Bí and ĎI saw 13í would both be true.

Dr. Itiel Dror: Absolutely, and when we are talking about the expectations on the higher cognitive level, such affects would be even stronger than the perceptual context that I illustrated.  So if you have a bias, youíve kind of made your mind up unconsciously. When you come and look at the information, the brain will interpret and evaluate it in a certain way because we are very active in how we see and process information.  An example would be when you go to the airport and you wait for somebody to come out of the arrival hall.  You may incorrectly think that many people coming out are the person youíre waiting to see, this is because youíre hoping and expecting to see that person.  This kind of phenomena is the way the brain works, the way the mind works, and thatís what happens in fingerprints and in other areas where the mind can affect what we actually see.

Interviewer: Right, but this is a pretty important point, isnít it?  Youíre not challenging the idea that fingerprint identification is a science in the sense that everyone has unique fingerprints, but just in the same way you see someone coming out of the airport is in fact someone completely different.

Dr. Itiel Dror: Absolutely, Iím not challenging fingerprints as a science or the reliability of fingerprints, but when fingerprints are very hard to call, then you have a lot of elements that can influence the people who evaluate them.  Itís very important to examine the cognitive and the psychological influences that affect fingerprint identification.  The same phenomena we talked about is not limited to fingerprints or even forensic evidence; take how they evaluated whether or not Saddam Hussein had the weapons of mass destruction and many people made a mistake; or the police shooting of the innocent Brazilian man in London.  The psychological state, e.g., what people think around you and what you expect, all put you in a certain frame of mind. This frame of mind will affect how you see things and how you interpret them and it can all be done on a very subconscious level.  Itís not intentional, thatís how the brain works.

Interviewer: Right, now the problem here presumably is that while the fingerprint bureaus may be very good at identifying fingerprints, they are not necessarily very good at cognitive psychology.

Dr. Itiel Dror: Absolutely, that is what is needed in the fingerprint bureaus and in the fingerprint community, and they are doing so; they are starting to look into cognitive psychology, the psychology of fingerprint identification. It plays a major role in the processing, in the decision-making model of fingerprint and in other forensic identification. Examining this perspective has been relatively neglected in the fingerprint community.

Interviewer: Final point.  Can the public in that case, in your opinion, trust fingerprints as evidence in trials, in quite the unambiguous way that they have been presented up till now?

Dr. Itiel Dror: I think fingerprints is a very reliable forensic evidence.  The most problematic fingerprint is still much more reliable than eye witness testimony.  If somebody testifies they witnessed a crime and they are sure, a 100%, that they can identify the suspect, that is much less reliable than a very problematic fingerprint.  However, when you look at fingerprints, because itís such a highly skilled profession, a lot of the identification falls on the human expert. There are different types of mistakes and human errors that an expert can make.  We have mistakes which are just dishonesty, where you intentionally make a mistake. But when youíre honest and you try to do your job you can still make mistakes.  It can be negligence (e.g., that you havenít paid attention), it can be incompetence (e.g., that you havenít been trained properly), or it can be the cognitive phenomena that weíve talked about that can affect what youíre doing.  The last one is not the responsibility and the fault of the specific expert, itís more the system that has failed to take into account and to train fingerprint experts in this area.  Nevertheless, in the vast majority of cases, fingerprints are very reliable and important.  I think itís very important to have an inquiry on this in Scotland, because itís not only the issue of the McKieís, but also that of the specific experts involved; and more than that and most important, the fingerprint domain itself.  All these issues are still open and issues that I think an inquiry should look into and shed light on.

Interviewer: Dr. Dror, thank you very much indeed for joining us.

Dr. Itiel Dror: I appreciate the opportunity to discuss these issues.

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Until next Monday morning, don't work too hard or too little.

Have a GREAT week!