THE IDENTIFICATION PROCESS:  
TWGFAST AND THE SEARCH FOR SCIENCE

(This article is reprinted from the October 1999 issue of FINGERPRINT WHORLD Vol 25 No 98 pp 315 -- 325.  The article was given as a lecture at the The Fingerprint Society Lectures, Liverpool, March 19^th --21^st, 1999.  Thanks to Dusty Clark, CAL--DOJ, for sharing this article).

by DAVID GRIEVE, EDITOR
Journal of Forensic Identification
International Association for Identification

In 1995, the Technical Working Group on Friction Ridge Analysis, Study and Technology, probably known more commonly by the acronym TWGFAST, was established.  With continuing sponsorship from the FBI, TWGFAST created what may be described as the first peer review panel ever assembled in the US to address technical issues related to latent print operations.  The initial 1995 group was presented with the task of reviewing the status of latent print examination within our country and was asked to determine if some form of written guidelines pertaining to specific aspects of the discipline might be warranted and beneficial. That 1995 group concluded that a collective exploration into latent print activities was, indeed, a worthy project that was both needed and justified.  The group has since been enlarged to about 40 participants and encompasses a remarkably balanced cross--section of American agencies representing federal, state and local departments.  In February, 1999, all technical working groups supported by the FBI were renamed as scientific working groups and, as a result, TWGFAST now sports a new acronym which sounds like the last call before closing in a neighborhood pub -- SWGFAST.

SWGFAST, by any name, has thus far provided three published guidelines which address the topics of examiner prerequisites, training to competency and quality assurance.  These guidelines offer models of what may be described as “best judgement” from a group of highly dedicated and professional participants who also represent a broad spectrum of philosophies and approaches.  The guidelines are products of a consensus, one first achieved within the committee which drafted them and, then, within the entire working group who literally tore them apart and put them back together.  The proposals which survived this consensus--building process then faced the scrutiny of public review which included general publication and several open forums conducted at various International Association for Identification meetings.  All comments received were then discussed and debated by the group, and many were included in the document before final adoption was achieved.   These three guidelines have since been endorsed by the IAI and are now a matter of public record.  While compliance with these guidelines is strictly voluntary, I believe any agency or individual would be wise to heed the collective wisdom contained within them.  In addition, adopted guidelines have been reviewed by the American Society of Crime Laboratory Directors Laboratory Accreditation Board and have been incorporated into their laboratory accreditation process.

Three additional topics are currently under discussion by SWGFAST, including one dealing with the very broad subject of friction ridge identification standards.  This committee, which I chair, has undertaken what we knew would be a most ambitious, demanding and controversial area of study, but a topic which is vitally important.  Achieving consensus standards in a discipline as entrenched as fingerprints is not an easy task.  Our respective ways of doing business have a long history, and they have served us, for the most part, reasonably well in spite of some glaring examples to the contrary.  Our committee has made considerable progress toward reaching common ground, although we do not yet have a final document for full working group consideration.

Some practitioners outside SWGFAST have argued that we do not need to formulate consensus standards and that status quo is just where we ought to be.  Their comments have omitted the fact that status quo is often different from one agency to another, from one region to another and certainly from one country to another.  Perhaps, as these people claim, exploration into methods and procedures, let alone identification standards, will prove to a waste of time and effort.  Nevertheless, if we have achieved a position of nirvana in fingerprints, then a review of what we are doing, how we do it, and more important, why we are doing it, does no harm.  On the other hand, if we can improve our understanding of the entire process by conducting such a review, then we will surely gain.  Any such review must be extremely thorough and as objective as possible.  We must examine not only the validity of our results, but the fundamental basis for how and why we execute each activity involved in analysis.  Probably most difficult of all, we must clearly delineate our explanations, reasons and justifications by use of a language that is clear to all, for if we cannot comprehend each other, then we cannot expect anyone outside our area of expertise to do the same.

I am not here today as an official representative of SWGFAST, nor do the opinions or statements I express represent any position adopted or endorsed by
   SWGFAST or the committee I chair. My views are, indeed, my own.  Instead, I offer these observations based upon the 34 years I have been a fingerprint examiner, and the more than 30 years during which I have been actively involved as a fingerprint trainer.  For the first 14 years, I provided instruction as required and did so in a manner generally patterned after the way I was trained – extensive repetition of the subject matter, considerable one--on--one guidance, and a strict adherence to what I believed were the unshakable principles of fingerprint identification.  However, during the past 16 years, I have been an instructor in a system that trains all new scientists, including fingerprint examiners, by means of highly formal, structured programs that are not unlike university courses.  My students are required to live in the vicinity of my training laboratory for a minimum of two years, although most will be transferred upon completion of training.   For these two years, my students devote their full time to the task of learning and I devote my full time to the task of instruction.  These students must have a university degree in one of the sciences, but prior experience with fingerprints is not required, nor is it desirable.  This simply means they enter the program with no preconceived notions, either good or bad.  Using what I define as a modified heuristic process, I have trained nearly 50 individuals, and by all internal and external skills--assessment testing, including their performance in actual casework, they are all doing exceptionally well.

Development of this training program required me to reexamine what I had been taught according to the same standards of science applied to all other forensic science disciplines.  I happen to work in a laboratory environment, and while I firmly believe that fingerprint analysis should be a laboratory responsibility, I discovered that much of what I had been told about fingerprint identification did not fully satisfy scientific scrutiny regardless of whether the process is conducted in the laboratory or as a police function.  I also determined that what I had not been taught was, in many respects, more important than what I had been taught incorrectly.  So, with your indulgence, I would like to relate some of the explanations about basic concepts that I have learned and what I provide to my students, concepts which I believe must be clearly understood before the first fingerprint is ever examined.  Many of these have been discussed in committee, and I believe some of these will be put forth in our final document.

One of the fundamental principles governing the world around us requires nearly all living organisms to possess a high degree of sameness between a male and a female before successful propagation can occur.  This requirement of sufficient sameness is integral to a natural order that enables the endless variety of plants and animals inhabiting this earth to maintain their integrity as a species.  The true marvel of nature is that the product of this procreation will not only reveal the same general attributes and characteristics as those of the parents, but the new entity will also be amazingly unlike any other of that species.  The level of this variation is so profound that all new organisms differ from all those that lived in the past, are living in the present or will live in the future.

How this occurs as part of nature's incredible order has been studied for centuries in an effort to comprehend those mechanisms which enable any given representative of a species to display both the sameness of inherited traits and the differences of novel features, and exploration into our understanding of how continues in the monumental project to unravel the complete composition of human DNA.  However, the why of nature's plan was barely understood, if at all, until Charles Darwin advanced his explanation of just what natural selection and species survival were all about.

Continuous biological variation, nature's requisite for survival, applies equally for all species, including our own.  As human beings, we all possess distinctive attributes and characteristics which describe our genus, and our catalog of sameness establishes a comprehensive and detailed inventory of the particular animal known as Homo Sapiens. Our biological classification defines us as a species and distinguishes us from all other forms of life.  Indeed, our list of class characteristics, those shared by each and every human being, is a rather formidable one, with common attributes ranging form a general description of our outward appearance to the chemical arrangement of our molecular construction.  Yet, in spite of the extensive list of what encompasses the sameness to all human beings everywhere, each individual member of our species is also distinctly different from all others in far more diverse ways than are the obvious bonds of our common traits.  

In spite of our high degree of sameness, the even higher level of difference we possess allows for reliable and often needed methods of distinguishing one person from another.  Successful differentiation depends upon an accurate awareness as to which parts of our characteristics catalog are truly common to all and which parts are distinctly individual.  To differentiate  properly, we cannot interchange those characteristics which we actually have in common with those which are truly individual, and, more importantly, we must never assign the false label of commonality to those features that are properly unique.  Only with reliable knowledge can we devise methods which recognize those features that are the properties of only one person.  Only with accurate knowledge can we achieve sufficient precision in that recognition to ensure verifiable protocols, thus establishing a science.

Fingerprints are the most commonly used means of differentiation in the world today, largely because they can differentiate to the level of individualization.  As such, fingerprint practitioners freely refer to the protocols they utilize as being scientific in their application as well as their foundation.  Yet in spite of an almost universal acceptance of fingerprint usage, the methods upon which this means of differentiation is practiced have few, if any, globally accepted guidelines or standards.  This lack of international protocols and standards extends beyond just some quirks or eccentricities peculiar to a particular region or nation, but pertains to disparities in the fundamental concepts, attitudes and approaches that direct the various applications.  These disparities are based in large part, I believe, upon misunderstandings concerning just what about us is truly the same and what about is truly different, and this, in turn, has led to a wide--spread substitution of dogma for science in the very core of the process.

Dogma is a strict adherence to some idea, one often presented as a pure and simple truth, but as Oscar Wilde noted, truth is rarely pure and never simple.  Dogma demands that one has a belief in the particular doctrine as a matter of faith as well as a devotion to its purpose as a matter of duty.  Dependence upon a dogmatic approach may be appropriate in some forms of applications as long as matters of faith are not confused with matters of science.  However, as a guide for developing the protocols for differentiation by fingerprints, dogma falls noticeably short, as evident by the following examples:

· the establishment of arbitrary minimum quantity requirements, either formal or informal, before an identification can be reported;

· the variations in these arbitrary minimum quantity standards around the globe;

· exceptions to the arbitrary minimum quantity requirements based upon the nature of the crime or if marks of the same person are found twice;

· a lack of agreement as to what constitutes the elements of a minimum quantity requirement;

· conclusions as to individualization which are expressed in terms of full or partial or probable;

· written reports which state that some number of so--called “matching” characteristics were observed between two impressions, yet disavowing any specific conclusion as to identity;

· and inferences that a single fingerprint impression could have multiple origins as required in a literal interpretation of the IAI's Resolution V, the amended version of the infamous Resolution VII.

Regardless of the rational for these practices and others, they are not rooted in science.  In fact, science abhors the inconsistencies that dogma creates.  We are told repeatedly fingerprints are unique to each person, then we are taught the “proof” of that statement is based upon alleged empirical data in which no two people have been found to have the same skin arrangements, as if we continue to look because we are not sure.  We are told repeatedly that ridge formations of certain shapes are called individualizing characteristics, then we are taught that two different individuals can have some of these individualizing characteristics in presumed commonality.  In North American, and coming soon to the UK, we are taught that there is no minimum numerical quantity of characteristics needed to make an identification, then we declare a latent to be without value for identification purposes because it has an insufficient quantity of points.  We are told repeatedly that fingerprint differentiation is infallible, and, in the UK, you were taught that 16 points and triple check made it truly infallible, then we are confronted with specific instances of incorrect identifications, even in the UK.  Dogma disposes of these inconsistencies by shifting attention away from any questioning of rationale to the issue of individual ability and determination.  According to dogma, the cause of contradictions is not due to what is being taught or how it is applied, but to the person performing the task, thus making any fall from grace an isolated breech of faith.  Dogma, therefore, encourages a certain distrust of others and promotes the attitude that all other examiners would be nearly perfect if they would simply do things as I do, or were as devoted as I am.

Teaching dogma is relatively easy.  All that is needed is an extended training time for repeating credos and platitudes until they have taken root in the student. What is usually not taught is the protocol of the scientific method, how to formulate a hypothesis, the prudent value in the formulation of a counter or null hypothesis, the ways in which experimentation and comparative analysis are used to prove or disprove the stated theory, and the means by which evaluation and validation are applied to the results. In short, students are usually not properly taught about sameness and difference, at least not in a way that enables them to understand what each truly is, how each is caused and to what extent each may be recognized.

Because recognition is an essential element of comparative analysis, I think it is important to comment briefly about this important topic.  We routinely and almost instantly recognize a spouse, a child, a friend, a co--worker, or even a celebrity or public official, with little awareness as to the complexity of the task.  Recognition as a process is based upon a largely subconscious comparison of sameness and difference between some current information we receive and stored mental images created by our prior observations and experiences with the same person.  We acquire these incredibly detailed stored images over a span of time during which we catalog the person's individual traits. This stored information is then tested and refined each time it is accessed, a process which reinforces what we have right and modifies what we have wrong.  In the recognition process, our analysis will often rely upon the most subtle and minute examples of agreement and discrepancy between the current information and the stored images.  While this process involves a multitude of steps, the results are remarkably precise and reliable.

As the information we receive becomes increasingly abstract, we will still attempt to associate new information with previously stored images.   This applies equally to all objects we encounter for the first time, either people or things.  We may see an unknown flower or tree, yet the abstract shape of the new image will conform to our stored images of similar flowers and trees.  We will note the sameness in these new shapes to our stored image file, and while we perceive the differences of the new shape, the overwhelming degree of sameness convinces us we can classify the new image as a flower or tree.  As new objects become almost entirely abstract in shape or form, the recognition process still depends upon a review of sameness and difference to previously stored information.

The human brain excels at organization, and will always attempt to restructure abstract information, particularly irregular shapes and forms, into some image with which we already have a level of familiarity.  This restructuring can be noted in examples as far--ranging as seeing Orion in the stars, elephants in a cloud or a face in the shroud of Turin.  The human brain searches images already stored and tries to establish a link from one or more previously stored images to the abstract form.  Once this link is established, it becomes very difficult for us to break away from that image and once again see the abstract shape as it truly exists.

Fingerprint examination involves recognition during which images are compared, but with notable exceptions.  Instead of a directed comparison of what we are seeing to stored mental images, we are confronted with two current visual images to determine if they are from the same origin.  To accomplish this, we must examine the two images for sameness and difference, but our perceptions as to what is actually sameness and what is actually difference rely upon our past experiences in analyzing similar abstract forms.  How we process the new information, therefore, will depend upon what we have been taught about sameness and difference in the images before us and how we have previously stored similar images.  If we are taught incorrectly as to what constitutes sameness or difference in certain shapes, then our ability to differentiate accurately becomes impaired.  If we are taught that general ridge forms and shapes are the elemental factors determining individuality, then we can easily fail to observe sameness and difference beyond this level. If we are further taught that all specific types of shapes and  forms have sameness, we can easily disregard or minimize the critical elements of difference that are available.  In the presence of overwhelming difference in the two images, the association of false sameness to some of its isolated parts usually causes no harm.  In the presence of minimal information, the failure to denote properly which is which usually leads to indecision.  In the presence of minimal, confusing information, the assignment of false sameness to instances of actual difference can be disastrous.

Systematic efforts to recognize differentiation began in the late 1870s when Alphonse Bertillon devised what he called  “anthropometrics,” a system based upon the hypothesis that no two people are exactly alike in all detail.  The Bertillon system therefore attempted to denote individual differences, and did so according to a series of diverse bone measurements.  According to Bertillon's theory, differentiation would become evident by a process of elimination, beginning with full body height as a key to offer the initial segregation, then progressing along a path of greater and greater discrimination.  The only true issue in Bertillon's approach was the extent of the measurements that would be required before individuality could be demonstrated.

Bertillon's creation enjoyed nearly two decades of acceptance before fingerprints were introduced to replace anthropometrics as an advantageous means of differentiation.  Fingerprints were heralded as a superior system that offered greater simplicity in operations and greater accuracy in the results.  Promotion of fingerprints as the more reliable method produced an inevitable clash between the radically different approaches.  However, romanticized, if not dogmatized, accounts of the development and advancement of both anthropometrics and fingerprints tend to distort the significance of these two events.  Bertillon is often portrayed as an irascible fossil who stumbled upon an inherently flawed and intractable system doomed to failure even before it began.  The champions of fingerprints, on the other hand, are all recalled as innovative pioneers who, with the possible exception of Henry Faulds, are practically angelic in their vision.   William Herschel is remembered as a man of almost divine inspiration, but someone who was, unfortunately, ahead of his time.  Edward Richard Henry is revered as a man of practical insight who almost single--handedly convinced the world of the infallibility of fingerprints.  Even Faulds, the only person slighted without knighthood, is characterized as an incredible visionary who was exceedingly progressive in his advocacy of utilizing crime scene marks.

Among those singled out for homage during the advent of fingerprints,  Francis Galton is generally given exceptional praise.  Galton was selected, albeit second--hand, to pursue the first scientific study related to fingerprints in the famous Faulds to Darwin to Galton exchange.  Recognized as an “expert” in anthropometrics, Galton began his research in 1888 with the full expectation of validating anthropometrics, and included a thumb print as more of an appeasement to Faulds than an initial belief in fingerprint individuality.  Educated in medicine and specializing in genetics, Galton brought impeccable credentials to an inquiry that until that time had been largely nothing more than intuitive.  Although Herschel and Faulds would later be vindicated, neither man had operated on much more than speculation backed with very limited empirical data.  Galton's study, completed in 1892, supposedly provided the missing proof.

A careful examination of the supposed foundation for fingerprint individuality provided by Galton, especially when contrasted to the foundation used by Bertillon, reveals that in the one vital requirement for differentiation, Bertillon was correct, while Galton was essentially wrong.  Bertillon's premise was deeply rooted in the biological uniqueness of all human beings, and presented a most convincing argument that has been substantiated by nearly one hundred years of fingerprint application.  In fact, the true foundation for friction ridge differentiation rests with the basis of anthropometrics, not with Galton's alleged scientific conclusions about fingerprints.  In this crucial aspect of sameness and difference, it was Bertillon who practiced science.  Conversely, Galton was the person who relied upon dogma, and key factors of that dogma persist to this day.

Science can only be as precise as the accuracy in its measurements, and here is where Bertillon encountered his greatest difficulty.  His instruments of measurement, while appearing advanced for his time, are, by today's standards, simply too imprecise to accomplish the task reliably and consistently.  If modern devices could be employed to record eleven body measurements similar to the anthropometric procedure but did so with nanometer precision, differentiation would be assured, even between identical twins.  True, the factor of permanence would remain a problem, but only with those who had not yet reached full bone growth or those who experienced later life changes occurring over an extended period of time.

As much as Bertillon, either knowingly or from intuition, capitalized upon the essence of biological variation, Galton largely ignored the subject.  Evident throughout his study were the hypotheses of a geneticist who had been trained to believe that all common species traits must be inextricably linked to heredity, and all people had fingerprints in common.  To his credit, neither Galton nor any other scientist of his time had access to what occurs during fetal development of friction ridge skin – the swelling and receding of volar pads, the chaotic formation of tactile nerves and sweat pores by the thousands, the explosive growth of cells around each pore to form ridge units, and the final transformation of thousands and thousands of units into separate ridge paths – with each stage influenced as much or more by a series of incalculable external stresses as they are by the overall genetic blueprint.  Without this knowledge, Galton could only assume that the influences of genetics were the deciding factors in fingerprint design, and the variations he observed were the product of what he called unknown messages possibly augmented by the normal and expected rate of mutation.   He may have been aware that the inside of the hands and bottoms of the feet had more than three times the concentration of sweat pores than any other area of the body, thus increasing the rate of so--called randomness, but it s apparent that he failed to appreciate just how individual the growth and development of each pore would be.

Instead of building his foundation upon the infinite examples of human differentiation appearing throughout the entire friction ridge skin.  Galton addressed only one  aspect of this amazing display of biological uniqueness, those ridge events which were highly recognizable and describable, thus permitting convenient labels as to shape and form.  He concentrated his attention, and the attention of those who followed, upon the terminus of a ridge path, the single isolated ridge unit and the ridge paths which split to form two paths, and he declared that the location of such events was obviously random.  In one sense, his observation possessed a certain truth, for the occurrence of these events are unpredictable and thus create no discernible pattern.  But absence of a repeatable pattern is but one facet of the individuality contained within a one--of--a--kind design.  By overlooking the entire display of uniqueness, Galton had little choice but to exploit the readily observable randomness of only a small portion of the design, and he justified the claim of uniqueness upon statistical probability, not biological variation.  This statistical approach, therefore, relies upon the location of a quantity of gross features with almost complete disregard for what other information may be present.  Using a calculation of simple probability, Galton reasoned that an agreement of twelve such random gross features between two fingerprints from different people would never occur because the odds against such repetition exceeded the world's population.  

Galton's discussion and explanation concerning individuality argued that the friction ridge gross features of each person were statistically unique, but not directly the result of inherent biological variation.  The repercussions of this approach have largely been responsible for a certain dogmatic attitude that has prevailed for nearly one hundred years.  While statistical probability can be applied to many scientific explorations, attempts to demonstrate differentiation by statistical analysis, no matter how large the numbers involved, does not preclude duplication from occurring at any given time.  Since duplication can occur, no matter how remote the possibility, statistical probability cannot predict when such duplication may happen again or again.  The statistical probability of any one person selecting the correct numbers of a lottery is astronomical, implying that the lottery can never be won.  Yet lotteries have winners, and prizes are shared with regularity.

The awareness that statistical probability, even those utilizing huge numbers, does not prohibit duplication at any time encouraged the addition of an empirical corollary to the basis of statistical isolation by fingerprints.  In essence, the empirical approach states that millions of fingerprints have been compared daily for nearly a century, but, to date, no two like fingerprints from two different people have ever been found.  While this claim may seem to substantiate the validity of Galton's statistical probability calculation, relying upon this type of so--called empirical evidence also implied persistent monitoring was required because there was a chance of duplication, no matter how remote.  This principle of uncertainty was demonstrated by a recent study conducted within the US in which all state bureaus were asked if they had ever discovered fingerprint duplication in two different people.  Once again, the biological origin of differentiation becomes neglected while anecdotal information is preferred.  This is the equivalent to polling how many times people have observed an object fall up as a scientific explanation of gravity.  The result may obtain staggering numbers, but even staggering numbers do not furnish proof.  The old reference that an infinite number of monkeys with an infinite number of typewriters and given an infinite amount of time will reproduce Hamlet only illustrates the vastness of infinity, not the statistical isolation of what constitutes genius.

The reliance Galton placed upon a statistical demonstration of fingerprint non--duplication has another flaw which is often repeated as part of prevalent dogmatic discourse.  Statistical individuality assumes that differentiation will be determined only after a certain quantity of randomness in relational ridge formations has been located and observed.  Conversely, statistical probability also assumes that once the quantity value necessary for statistical certainty has been determined, a progressively decreasing number will automatically include an exponentially larger and larger portion of the population.  Statistical inclusion declares an inability to differentiate, and implies that those formations existing below the threshold quantity have a shared commonality, a shared sameness.  This approach, in essence, refutes biological differentiation as a natural and consistent occurrence and strongly suggests that a significant part of any fingerprint is not actually unique.  This creates the conundrum as to whether anything which is unique in its entirety can be constructed of parts which have indistinguishable commonality with something else.  The most appropriate answer depends upon the manner in which differentiation is perceived as opposed to how differentiation truly exists.  In short, statistical analysis is meaningless unless we have correctly determined what is sameness and what is difference within our species.

Any expression that parts of a fingerprint are actually a shared class trait of sameness while other parts are an example of non--repeated difference disputes the very premise of biological differentiation and severely weakens the foundation fingerprint individuality itself.  Perhaps more important than this apparent dichotomy to nature's prohibition against exact duplication is the mind--set such contradiction creates within the examiner.  Those who state, and many have, that they found two different fingerprints which shared a certain number of points in common commit more than a violation of a fundamental tenet of nature and, by default, the fingerprint science.  Such statements reveal an uniformed allegiance to dogma as well as a resounding rejection of all science.  Indeed, unique entities may share certain characteristics and attributes which are included in the definition of a particular class, but they may never share what has been acquired through the one--of--a--kind experience of individualized fetal growth.  To imply otherwise promotes a basis for myth and superstition which so often arise when knowledge and understanding are replaced by the closed--mindedness of self--perpetuating dogma.

Either biological uniqueness exists or it does not.  All of our observation since recorded study states that biological uniqueness is the lynch pin for survival, and this uniqueness cannot be partial, quasi, sometimes, nearly or virtual.  Based upon all we know, the prohibition against exact duplication is absolute, and even cloning cannot inviolate this decree. Nature has always cloned.  Monozygotic twins begin and remain genetically identical, yet, after fetal growth, are distinctly unique.  Any portion of a fingerprint, no matter how large or small, has only one source of origin, and all features of that fingerprint,  no matter how minute or noticeable, originated from a single source.  Since all features are individual, all have the potential to reveal differentiation.  As with anthropometrics, differentiation requires a series of measurements which can verify or disprove the identity of the individual when compared to a known standard.  As with anthropometrics, the central issue is just to what extent measurement will be required before individuality can be concluded.  As with anthropometrics, the accuracy and reliability of the results will be directly related to the capability for precision in this measurement.  When measurement includes all available features, the resulting analysis, a comparison and evaluation are founded upon science.     When measurement excludes certain areas of discriminating features and presumes sameness to others, the resulting examination is buried in dogma.

Galton established a de facto base measurement by selecting ridge formations of distinctive and familiar shape, although these only included a small portion of the individuality within each fingerprint.  His emphasis upon a marked event occurring to a ridge path directed attention to a highly restricted category of information, and even planted the concept that formations of similar shape were almost interchangeable, that is, a bifurcation is a bifurcation is a bifurcation.  Even adding directionality – bifurcations opening upward, downward, right or left -- does not state categorically that each and every bifurcation is unique, as is each and every ending ridge, island, enclosure or other gross formation.  These are not elemental portions of friction ridge skin any more than a nose is an elemental part of a face, and one quick glance around this room will demonstrate what biological variation is all about.

As I stated previously, the human brain excels at organization, and processes new information by establishing links to that which is already stored.  We tend not to process information for which some link cannot be readily established. What we do have stored is the result of what we have learned, either what we have been taught or what we have acquired through experience. If we are trained to ignore morphological shapes or forms, such as ridge edges, ridge pores, or creases, then they will have little or no significance. If we are trained that a given shape or form has a presumed commonality to other shapes or forms of similar appearance, then we will have a difficult task to perceive anything but sameness.  We will, of course, note direction and relationship to other gross formations, but we still will not readily see what we have not been trained to see.  As a result, we will compare part of an image to part of an image, and in many instances, that will be enough to differentiate.  In the other instances, unfortunately, we will fail to either correctly identify or to identify in error.  However, if we are taught to understand and recognize that every feature of a fingerprint is distinctly individual and unique to that one person only, then we compare full image to full image, and we are only limited by the accuracy of measurement each image possesses.

All images involved in fingerprint comparisons are only reproductions of the original morphological arrangement of friction ridge skin.  Precision of measurement is determined by the quality of that reproduction, and as any examiner knows, the range of that quality can be considerable.  Crime scene marks will display a quality influenced by factors often too numerous to estimate, and even inked standards will reveal extensive variation in quality depending upon the subject's skin, the medium used, the recording surface and the skill of the operator.  Accuracy of measurement, therefore, will be determined according to the degree of clarity.  Accuracy of measurement determines to what extent difference can be readily observed in any given area of an image, and, in essence, controls the quantity of information required before differentiation can be demonstrated and assured.  For any fixed numerical standard to be valid, the factor of quality, one which is at least co--equal in importance as quantity, must be assigned a similar numerical equivalent.  However, since quality cannot be quantified, a fixed numerical quantity standard has no scientific basis.

Lack of clarity in minute detail does increase the need for a greater quantity of information, but diminished clarity does not assign commonality or sameness to any of the features that may be present in an image.  By that, I mean that nothing about even the smallest element of a ridge is a class characteristic of a fingerprint, but remains something as different as the entire entity who grew it.  Our inability to obtain a high level of accuracy in our measurement only disguises the specific features of uniqueness, but never removes or transforms these manifestations of individuality into something that is shared by another person.  Surely recognition of sameness or difference may be difficult and even impossible, but what we view, no matter how small or indistinct, is still unique.

The dogmatic approach claims we are unique because we have different fingerprints.  Science states we have different fingerprints because we are unique. Just as we must correctly delineate among what is truly sameness, what is truly difference, and what is nothing more than our inability to measure sameness or difference with sufficient precision, we must understand the distinction between cause and effect.  It matters little whether we can demonstrate uniqueness with statistics or not, for the truth will remain the truth in spite of what we can or cannot demonstrate according to our own mathematics.  Mankind must get over its arrogance in believing that nature's truth can only be mankind's truth when and if mankind says so.  In addition to different noses, we have different ears and different lips, two types of impressions which are constantly challenged because they do not have the same foundation as fingerprints.  I maintain that all traits obtained by biological variation possess uniqueness precisely for the same fundamental reason.  For proof, we only have to marvel at the fact that we as a species, in spite of our best efforts to the contrary, have managed to survive because we are all products of biological variation.  This natural law is the reality that encouraged Bertillon to isolate difference from sameness which Galton failed to do properly.

I am not a champion of Bertillon, nor am I necessarily a detractor of Galton, but I believe that I am an examiner who became a scientist, and I train others to be scientists.  I am also one who believes the fingerprint profession has a compelling need for greater standardization in all of what we do, but particularly in the identification process, the act of differentiating one person from another.  Differentiation by fingerprint will always be valid when it is based upon scientific principles derived from understanding both the cause and effect of uniqueness.  As a result, our understanding of why and how differentiation by fingerprint is possible must be the same in the United States, Canada, Great Britain or any other nation on earth.  The Friction Ridge Identification Standards Committee of SWGFAST has begun the work of proposing standards for US examiners, but these will not succeed unless we first establish a mutual understanding of what constitutes sameness and difference in friction ridge structure, unless we first achieve a mutual acceptance of what we mean in the very language we use, unless we first derive a mutual agreement in the principles and methods applied to differentiation, unless we first develop a mutual approach to the training of others in these fundamentals, and unless we first affirm a mutual regard for the science that supports our efforts.  The excellent work done by David Ashbaugh in “Ridgeology” is only a beginning to what we must learn and understand.  We must continue that effort by reaching our mutual understanding, acceptance, agreement, approach and regard with the ultimate goal of an international accord.

Several years ago, I received initial support from the Illinois State Police and the US State Department to my proposal to conduct an international congress to begin this long and difficult process. Unfortunately, the proposal has languished for lack of funding.  My hope is that the day is not far off when concerned examiners from throughout the world can meet to begin the monumental task of developing this mutual understanding in the spirit of the 1995 Ne'urim Declaration, which reaffirmed the principle of the 1973 IAI Standardization Committee report.  I have an abiding faith that we are not as diverse as we may seem, at least not the results we obtain, and that there is a higher level of sameness in what we do than what we say we do.  We begin, I believe, by clearly defining our terms, by clearly delineating our purpose as well as our methods, and by strictly adhering to science by discarding the dogma.  The time to begin this most difficult challenge is now.

[Editor – This outstanding article presents an important topic “the search for science” or what could be called the search for scientific standards.  The establishment of standards based on proper scientific methods is what I believe is the underlying goal for each of the many scientific working groups and why I am such a strong proponent of the SWG's.  As regular readers of THE PRINT will recognize, this editor has long advocated that we need scientific standards to establish consistency in the workplace and ultimately for judicial review.  This is not to recommend “point counting,” as Dave so aptly rebuts and succinctly declares “since quality cannot be quantified, a fixed numerical quantity standard has no scientific basis.”   I would add my two cents worth of argument (editorial prerogative) for any “point counters.”  How many circles which supposedly indicate minutia points on a skeletonized image does it take to go to court?  Without any ridge detail quality, the image below is what you have accepted for comparison.  It includes level 1 and 2 detail, but without quality of ridge detail, what is your confidence in the ridge paths and ridge terminations, and ultimately in a conclusion.  So, how many of the little tailed markers does it take?  A few examiners continue to offer a waning debate while they cling to numbers.  The debate that counts has been two--fold:  the professional debate within the forums of professional meetings (SWGFAST has done that internally, and at IAI and state meetings with the presenting of its Quality Assurance guidelines) and the judicial debate.  The judicial debate was provided in the Bryan Mitchell case and the court did not require a number.  I would call for the point counters to relinquish their position and accept the standards which have now been established.]

This article was printed in “THE PRINT”
Volume 15(5) September / October 1999, pp 1 -10
and has been obtained from the online library provided by the
Southern California Association of Fingerprint Officers
www.scafo.org