Fingerprint Dogma

[Guest]

Premise: Fingerprint Identification/Individualization is based on two basic "scientific" principles:
1. Permanence or Persistance
2. Uniqueness

The first mentioned principle does not seem to get us into any trouble. It is that second entry, uniqueness, that causes consternantion.

A quiz:
We constantly hear about biological uniqueness and there are some references to the axiom that "nature never repeats itself." Now, we know that nature does repeat itself, especially at the molecular and cellular levels. If it did not we would all be shocked at what was staring back at us from the mirror each morning, we would have no functioning organs nor an ability to heal ourselves. Let's face it, we would never have developed beyond our single cell beginings. And, how could we lay claim to that first principle, persistance, if nature could not recreate and maintain ridges? To those who would suggest that nature repeats itself only within the same host, I offer the phrase "stem cells." So I ask you, who was it that first suggested this priciple of biological uniqueness? At what level was uniqueness first observed? Where was this principle/theory first published? What experimentation was conducted to verify this observation? Who first applied this principle to fingerprint ridge detail?
Thank you all for your considered opinions.

[foren6]

Your questions and observations are extremely relative to the many problems that plague the forensic sciences, especially the so-called "science of fingerprints."

I, as well as others, suspect that the uniqueness aspect of fingerprints arose from the overly simplistic (and undemonstrated) idea that "nature never repeats itself" and "all snowflakes are unique." I agree with your point that if nature never repeated itself, we all would have different organ systems and anatomies. We also wouldn't have identical twins in existence. On the topic of identical twins, there have been documented similarities with twin fingerprints. However when "complete ten-print fingerprints" are compared, there are implied differences in minutia. But what about latent prints? There needs to be more research on this topic.

That leads me to another point. If you ask fingerprint examiners about research, invariably they will site work that was done 30-60 years ago that centered on embryology and fetal ridge development. This is all fine and dandy but it is often used to placate the person asking about research in the "fingerprint sciences" and evades the fact that there is a lack of research in latent print identification...the bread and butter of fingerprint comparison. Also, a common trend is to cite the so-called "50k study" that has been highly criticized and largly discredited. It is also curious that, to my knowledge, the 50k study has never been published in a scientific journal.

As a scientist I have been disappointed about the lack of scientific research to support many claims in the forensic sciences. Trying to determine the genesis of many claims in the forensic sciences is somewhat futile. I think some of it is generated by people who have lacked training and education in science and therefore lack the understanding on the importance of research. I mean afterall, if a dreamed up idea sounds valid...then it must be! Right? Wrong. It must be demonstrated through research.

If you study the history of forensic science you will find that many disciplines have been staffed with folks that lack any kind of scientific background. This is especially true in fingerprint comparison. This is starting to slowly change and will hopefully be accomplished in my lifetime. There is still a pervasive negative attitude about people with degrees that are trying to learn and practice fingerprint comparison. There seems to be a "guild mentality" among the more senior examiners that is forced upon younger people who want to learn to be fingerprint examiners, but have a degree. It's as if having a degree is threatening and serves to work against the person that posseses the degree. To get a flavor of the ignorance and hate that some fingerprint practitioners harbor, study the postings on this website and on ONIN. I want to know how many of these degree hating examiners have children that are sacrificing and working hard to get their degree? What hypocrasy and nonsense! But I digress.

I will suggest that you read Simon Cole's "Suspect Identities." You'll never hear the mainstream fingerprint crowd recommend this book, but it is a good read and it tackles the issues for which you are currently searching for an answer.

The bottom line is that research in fingerprint identification serves to possibly threaten the current status quo of fingerprint identification. After all, fingerprint identification is such a widely held assumption that lacks any serious or valid scientific study that any attempt for the fingerprint community to research it would only uncover the limits to what they can claim. The reason why the scientific community has not researched this topic is for the very reason that there has historically been a lack of research funding for this kind of inquiry. And funding is the stuff that fuels research.

Also, let me leave you with this parting thought. If you are contemplating a career in fingerprint comparison, please have a backup plan.

[Les Bush]

Hello guest

I'll keep this short because your identity is not known and I perceive a bias that is not objective. When the Law of Gravity was formulated what research went into that discovery? Has the Law of Gravity been disproven? It is a natural consequence due to the order of our universe and the birth of our planet. Ofcourse there are conditions by which the Law can be varied but generally it is sound. The same can be applied to the principles of fingerprint science. If you and I and your supporter Forensic6 were in a room and you still doubted the ability of fingerprints to separate our identities then please rest assured a fingerprint expert could do that for you. Study our texts and research the many experiments performed by experts then come back to me.

[Guest]

As regards gravity, and the origin of its theory, it goes far beyond the observance of Sir Isaac’s falling apple. The theory stated is:
Each particle of matter attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
The mathematical formula for determining gravity is:
Gravitational force = (G * m1 * m2) / (d2)
where G is the gravitational constant, m1 and m2 are the masses of the two objects for which you are calculating the force, and d is the distance between the centers of gravity of the two masses.
This theory has not only been proven over and over by scientists and researchers from Newton to Einstein, it continues to be examined today at major universities by physicists, mathematicians and cosmologists.
Now please notice that we have a formula, mathematically expressed which allows us to precisely calculate the effects gravity.
Would you please state the formula that I or any other person may use to establish the individualization of a latent print to a known source? If not a formula, than please cite the quantifiable standard which may be applied to such an exam.
By the way, the attempt to understand a phenomena and suggest the reasons or causes for its existence is not bias, its called science.

[Shaheen]

Without getting too much into the politics of it all, I would like to add a few plates of food for thought.

1) I believe that it is everyone's right (and responsibility if you are a forensic practitioner) to question or challenge how a conclusion is made. This is the basis of our adversarial system, and the reason why we engage in such debate.

On a healthy level, practitioners are naturally forced to improve their personal performance. It also forces the practitioner to become competent in the scientific reasoning that supports their profession, so that they can explain it to those who are not familiar with the premises, and who might otherwise be inclined to scepticism. So essentially you need to have the correct tools in order to engage in the debate yourself. This can only improve our profession.

So I appreciate the intention of "Guest" in this light who may not be familiar with the research into "embryology and fetal ridge development". It in essence shows that while the general shape of two fingerprints can be similar (very similar in the case of identical twins), the finer points (minutiae) in the fingerprint will be always different because fingerprints are formed in the womb as a result of pressures exerted on the foetus. Even with identical twins, these external pressures are random and so will be different for each foetus, resulting in different minutiae patterns. I can point you in the direction of these papers if you like.

2) We also need to be careful that our debate does not become unhealthy, or destructive.

In this regard, I have some comments and questions for foren6:

a) There will always be a need for more research. If you had reasonable resources, what specific research would you like conducted to satisfy your scepticism? To speak in generalities is unhelpful as there are different issues involved in different topics.

b) What are the inadequacies in the "embryology and fetal ridge development" research, and how can they be fixed or updated? I was not aware that in the last 30 - 60 years the way in which babies are made had changed... therefore I would like to understand why is it offensive for you to hear research from 30 years ago cited today, and secondly please enlighten us as to the deficiency in the work, because this is the only way in which we can improve.

Kind regards,
Shaheen

[Shaheen]

Dear Guest,

I appreciate your rebuttal re: gravity analogy. I agree on your comment on bias and science, and feel that earlier replies were more directed to the comments of foren6.

As an adjunct, I would point out that Newton's Law of Gravity was a first-approximation to Einstein's Theory of Relativity (from which you get the formula). I believe that what Les is trying to say is that in between Newton's law and the quantifiable equation, people didn't say "gravity does not exist". Instead they worked together to figure out what it was they were really dealing with. And they are still working on it, as you point out, so are we really 100% sure that the equation we have will apply in all cases?

In the same way, what we have now is a "first approximation" to fingerprint enhancement. And in some respects I believe that we need to continue to work on that approximation and build on it until we have, not necessarily a rigid equation, but a set of universal standards. And if you have seen earlier posts on CLPEX, you would know that we have been debating the variables and subjective elements of the fingerprint comparison for some time now for that very purpose.

On the other hand, we must examine the differences between the measurement of the gravity variables and the fingerprint variables. Mass and distance are fairly easy to quantify because we have spent a lot of time inventing sound methods of measurement. Clarity and quantity are a little more difficult to quantify at the moment as we have not been tackling the problem for long. But that is not to say that we will not come up with a good system as a result of our debate in the future.

In the meantime, instead of saying that "gravity does not exist", we will have to rely on the ACE-V method and its application by competent practitioners, as well as the ability of that practitioner to demonstrate their findings in court, and the process of re-examination, comparison and debate by other experts in court.

UNTIL - it is disproven as a science. Thankfully I don't think that is going to happen Maybe that's a bit of faith, maybe that's intuition. Maybe it's science!

I'm rambling now, it's time for some zzz.

Shaheen

[Guest]

In Scott's Fingerprint Mechanics, section 13 titled "Number of Characteristics Required for Identification," the author repeats the premise that "there is no valid scientific basis for requiring a minimum number of ridge characteristics....in order to establish positive identification" no less than three times stating that "It is necessary to to emphasize and reemphasize this statement in order to dispel misconceptions regarding minimum charcteristics and the frequently quoted twelve-point standard or rule."

I ask those responding to my posts to not merely refer me to previous studies or findings since that is not evidence that you know what they are. Please state what the findings were and who conducted the studies so that we can emphasize and reemphasize the support for fingerprint science. It is possible that many who participate in this forum do not have access to the studies alluded to in your posts.

[David Fairhurst]

Once again, in this forum, we have people using the words "law" and "theory" interchangeably and incorrectly.

A Natural Law describes the behaviour of a system. In mathematics and physics laws can be expressed as equations such as the one given for the Law of Gravity given By Guest above.
Examples of other laws.
Newton's 3 laws of motion.
1. An object will remain at rest, or in a state of constant straight line motion, unless acted upon by a force.
2. The accelleration of an object is proportional to the force acting upon it and inversely proportional to its mass.
3. For every force there is a reactive force equal in magnitude and opposite in direction.
Law 2 cam be formulated as F=ma. Can you, Guest, formulate the first and third laws?

Laws in biology are more complex, formulation may not be at all possible, as is the case with some of the laws of economics etc. This does not show them not to be laws. Laws describe what the output of a system will be given the input variables.

Theories, on the other hand, explain how a systen works.
Examples of famous theories:
Evolution by natural selection, plate tectonic theory of continental drift, atomic theory, germ theory of disease, chaos theory.
There is no generally accepted theory of gravity. Newton himself commented when defining the Law of Gravity that he could propose no explanatory theory of why his law holds true, and there is still much debate about why two objects exert an attractive force upon each other in this way.

Here are another couple of (not so serious) Laws for Guest and the rest of you to formulate.

Parkinson's Law: Work expands to fill the time allocated to complete it.
Murphy's Law: Whatever can go wrong, will go wrong.

Once again there is no theory to explain these laws, but many people still hold them to be true.

[Guest]

You are absolutely correct, Mr. Fairhurst. The distinction is extremely important.
My purpose is to stimulate thought, not excite controversy. Unfortunately, despite the Daubert successes, the scientifc basis for fingerprint identification continues to be an issue, hence the NIJ research grants into this issue. Now would anyone care to address the original questions I posed?

[David Fairhurst]

The Law of Physical/Natural/Biological Uniqueness states that all physical entities (above the molecular level) are unique in structure and can be distinguished from one-another.

Many theories have been applied in explanation of this law in relation to friction ridge skin. Alfred Hale's Theory of Differential Growth is the one refered to above, by Shaheen. Both Chaos and Fractal theories can be applied to biological growth throughout nature, not just to friction ridge skin. I admit that we do need to research more fully how these various theories do explain the Law of Uniqueness, but just as I believe that the Law of Gravity holds without a supporting theory, so I believe the Law of Uniqueness holds true.

Can you, Guest, argue with the following demonstration of the Law of Uniqueness?

I get 100 cocktail sticks and hold then in my hand 4 feet from the floor and let them fall. I now preceisely document the position and orientation of each of the sticks at rest on the floor. How many times do I have to repeat this process until I get a repeated result? Will the 100 cocktail sticks ever fall each in the same position and pointing in the same direction? What if I try to eliminate the variables such as where each stick is located in my hand at the start: devise an automated dropping device to hold and drop the sticks exactly the same way each time, drop the sticks in a vacuum to eliminate any effect of turbulence or wind on the motion of the sticks? Will I ever get a repeat result, or will increasingly precise measurement always show that there is some difference in how the sticks fall?

[Gerald Clough]

I do, in fact, recommend Suspect Identities for its coverage of the history of the field and current problems. Cole goes over the top in implying that genetics will replace fingerprints, but I understand that a "gee-whiz" notion provides a hook for book reviews and therefore something to catch an editor's eye when pitching a book that would otherwise have little general appeal.

Often, the debate becomes an all-or-nothing exercise. I don't think there will ever be an acceptable quantatative argument of uniqueness. (Or even a broadly accepted objective description of what the word means.) That shouldn't stop those so inclined and qualified from thinking deeply and seeking research paths.

But all proof need not be reachable by a deductive chain of generally accepted scientific facts. In the US, our criminal proof is, of course, "proof beyond a reasonable doubt." Although the Gessa jury charge on proof has been superceded a presumption that the jury will properly work it out for themselves, I'll paraphrase the old language as still a good way to explain the concept.

The doubt in "reasonable doubt" is the kind of doubt that would cause us to hesitate in the most important of our (the jurors') personal affairs. The court wisely stopped short of ennumerating those affairs, choice of spouse, purchase of a home, etc. People's frequent ill considered actions in those arenas in light of things that should have raised doubts rather threatens the analogy. But, jurors generally consider better their trial issues than their own personal experiences, so perhaps it still works.

Most of what presents as evidence at trial is not in any way ammenable to scientific analysis. Considerable expert testimony and opinion is likewise not scientifically "provable." It can nevertheless be argued coherantly so that a fact-finder may make a reasonable determination.

The point is that the principle that comparison of friction ridge impressions can determine identity beyond any sort of reasonable doubt is in no danger of being abandoned. To imagine anything else is pretty silly. Well, not silly, really, but ignorant. (There should be no offense taken to "ignorant". We are the most provably ignorant generation ever, there being more known today that individuals will never know than ever before.)

Things have changed and are changing. It's mostly good change. The bulk of the reasonable suspicion in Suspect Identifies cites error, from over-reaching to fraud to plain old poor work. It's good that, increasingly, we are expected to explain and argue our conclusions. Until we reach the unlikely position of absolute quantified proof, it is appropriate that conclusions be challanged. And it's appropriate that we be our own best critics and that we demand more of our own confidence in our conclusions. But the most easily, cheaply and commonly recovered valuable crime scene evidence we have available will not be abandoned or reduced to a commodity of doubtful value.

Some old notions, including some still in fashion, *will* be abandoned. But though the emperor's old clothes may have been largely illusory, stripped naked, he's still the emperor, and he still looks pretty good.

[foren6]

Shaheen,

Embryology studies are not demonstrations of identification of "latent prints." Instead they are studies into the "prioximate causation" of the formation of fingerprints. It is misleading when decades old embryology studies are brought up as proof that latent fingerprint identification has been scientifically studied in the past. The only thing that these embryology studies demonstrate is how the ridges are formed...which is important and is part of the large body of work within the field of embryology. It does not give scientific validity to LATENT PRINT IDENTIFICATION per se.

I am assuming that your comments about 'how babies are made has not changed within 30 years' is to be taken with humor, so I will leave it at that.

As far as latent print identification is concerned, a real need exists for understanding the limits for which fingerprint identification is reliable. For some reason everyone wants to ignore the very real problem of "points" and I realize that there is more to fingerprint identification than the existence of points. However, if you were to tell me that you had a latent print with 75 points of identification and a latent print with only eight points, assuming that latents were of the same quality, I would have a rough idea that the print that contained 75 points would be significantly larger than the print with only eight points. Having said that, it seems to me that the major erroneous identifications that have recently come to light seem to define a limit for which erroneous identifications are made. However, if you've noticed, these mistakes seem to always be swept under the rug and attributed to examiner error...even though some of the folks making the mistakes are senior examiners. My assertion is that what if these errors were a result of pushing the limits beyond resonable certainty? We will never know until latent print identification is adequately studied. It would also clear up the problem with the UK adopting minimum point standards and then abolishing them.

For research ideas, I think there should be an attempt to methodically classify the quality of fingerprints. I also think that simple research projects that explore the critical threshold of the number of points needed for identification, given the quality and the size of a given latent print, need to be performed. The difference between science and fingerprint comparison is simple. Science deals with limits. Scientifically sound concepts have limits. The limits are defined and scientists know if they have exceeded limits of certainty. I truly believe that fingerprint comparison can be a valid science. The fingerprint community can start by accepting people with scientific training into their ranks. I think there is evidence that this is starting to happen.

I think dialogue such as this is very important and healthy. Let me know if I can clarify my points in any way. I am not against latent fingerprint identification, I just want to see it develop into a science.

[Steve Skowron]

Just a quick message to those who would cite Simon Cole's work. Please visit the below web site and review the research done by a student of his, Rob Carpenter. Of special interest should be the 16 point mis-match. Some may say that this is scientific research done in an academic setting without bias. This "so-called" research could only "threaten the current status quo of fingerprint identification" if as Mr. Clough states; " We are the most provably ignorant generation ever".

Steve (no backup plan) Skowron

http://research.calit2.net/students/surf-it2005/?p=51

[Gerald Clough]

However, if you've noticed, these mistakes seem to always be swept under the rug and attributed to examiner error...even though some of the folks making the mistakes are senior examiners. My assertion is that what if these errors were a result of pushing the limits beyond resonable certainty? We will never know until latent print identification is adequately studied.

I don't think there can be much doubt that many of the errors we're talking about here are the result of pushing beyond proper limits, aggravated by other factors that militated for the mistakes to be confirmed. It may well be that this over-reaching is more likely to be associated with highly experienced examiners, for obvious reasons.

I think the needed study is as much inquiry into the culture and dynamics of latent units, the larger environment, as it is methodology of comparison. This seems evident from situations in which erroneous identifications were made and verified, sometimes by multiple examiners of different affiliations, and in which, once the error was discovered, everyone can then see that there was no match.

[Gerald Clough]

This "so-called" research could only "threaten the current status quo of fingerprint identification" if as Mr. Clough states; " We are the most provably ignorant generation ever".

The story does not appear in anything more than a campus blog and features equal portions of ignorance contributed by Carpenter and Cheung. It has no more effect on fingerprint identification than my twelve year old niece's diary.