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Monday, September 1, 2003

BREAKING NEWz you can UzE...
compiled by Jon Stimac

Missing Prints Could Affect Case - FT. WORTH STAR-TELEGRAM, TX  - Aug. 30, 2003 ...fingerprints lifted from a 1996 murder were inadvertently destroyed by police...

Fingerprints Lead to Arrest in 1969 Slaying - HOUSTON CHRONICLE, TX  - Aug. 26, 2003 ...the matching prints police needed to solve the case were found in the FBI's Automated Fingerprint Identification System...

Good morning via the "Detail," a weekly e-mail newsletter that greets latent print examiners around the globe every Monday morning. 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.


A course entitled "The Detection, Recovery, and Examination of Footwear Impression Evidence" is being taught in Jacksonville, Florida, this coming November 3-7, 2003.  If it is possible for you to mention this course on your web page, I would appreciate it.


Bill Bodziak



Last week, Carl Bessman shared some images and the story of a recent increase in the number of contaminated (with glue) latent prints found on bad checks in Iowa.  This week, David Fairhurst shares an article he wrote for Dave Charlton in Fingerprint Whorld a short while back.  It continues some thoughts posted recently on the CLPEX.com message board. 


Is Fingerprint Examination an Art or a Science?
by David Fairhurst

I was a somewhat surprised when Dave Charlton approached me at The National Fingerprint Conference asked me to write a series of articles for Fingerprint Whorld’. What could he possibly want me to write about? Is he really so short of material? As it turned out he had read the few thoughts I had posted the day before on the CLPEX.com chat board, and wanted me to ‘pad it out a bit’. Well I don’t consider myself a good essayist, having failed English Language O-Level at the first attempt and always having struggled to meet the word count on assignments at university, but after some thought, a good meal and a few drinks I realized that I could probably put something together that might be worth publishing.

The question of whether there is a place for art in fingerprint examination is like asking what happens to white light when it passes through a prism. The answer depends on the direction from which you look at it, and your answers will cover the whole spectrum. Before we attempt anything else we need to ask the eternal question "What is art?" or, more specifically, "What do we mean by ‘art’?" This is where I have to reach for my dictionary. I always like to start with the etymology of a word, particularly if its origin is Latin. I did rather better in Latin than I did in English at school. The word ‘art’ is derived from the Latin word ‘ars’ meaning craftsmanship. This is, of course, where we get the word ‘artisan’, and it leads us to the first group of definitions I would like to address.

Art – the exercise of human skill. To become proficient an examiner needs training, experience and practice to develop the skills required. It may be said that someone has got fingerprint examination ‘down to a fine art’, meaning they are highly proficient at it. There may also be ‘the art of fingerprint examination’ using ‘art’ to mean the method or skills employed, or even as a knack as in ‘the art of threading a needle’. Can we say then that fingerprint examination is artistic? Sticking strictly to these definitions we can, but would you be comfortable in saying so in the witness box? I have deliberately used the word ‘artistic’ in this question because of its closer association with the other group of definitions in my dictionary.

Art – the creation of works of beauty or other special significance. In this group of definitions we encounter concepts that are difficult to apply to our practice. Imagination, creativity and aesthetics are the focus of this art. Opinions formed in this field are derived from concepts such as taste and style rather than from a rigid protocol. Opposing opinions are equally valid because no rules exist to govern the process of forming those opinions. I think the Chrysler Building in New York is more beautiful than the Empire State Building but I wouldn’t say that anyone having the contrary view was wrong, though we do disagree. We each appreciate different aspects of the two things that we are comparing in different ways. Can this approach be used in fingerprint examination? If it were, could we expect a court to accept our opinions as evidence?

In the first usage there is no contradiction in describing fingerprint examination as an art. This is because art is not used in contradiction to science as it is in the second. This popular dichotomy of art and science, deeply rooted in academic society and the division of studies into Arts and Sciences, does not really exist. Indeed, if you follow the hierarchy of academic degrees from Bachelor through Master you reach Doctor and the distinction disappears, Artists and Scientists both become Philosophers. Art and Science are not mutually exclusive. There are aspects of each in everything and nothing is purely one without the other. Take as an example Leonardo da Vinci, the most talented painter, sculptor and architect of his time, if not of all time. But here also was an engineer, anatomist and inventor of equal stature. Artist and Scientist combined, perfectly. Looking closer to home, the history of fingerprints features two men worthy of mention here, Thomas Bewick and Nehemiah Grew. The former is described as an author, naturalist and artist. He used his artistic ability to embellish his work with impressions of fingerprints, probably his own. His engravings show that Bewick must have made a detailed study of the structure of the skin. The latter is described as a botanist and physician who published research in scientific journals. Grew’s artistic ability however was equally important to his work as his scientific method was, as anyone who has seen his drawings of hands and friction ridges would agree.

So, if there is a place for artistic ability in science, is there a place for it in fingerprint examination? What Bewick and Grew did was look at the ridges on their hands and held an image of them in their mind’s eye. Then, using their respective skills, created an impression of that image in wood or on paper. During this process they would be constantly looking back and forth between the hand and the impression comparing the two, making sure that the impression matched the hand as closely as it needed to for their own purpose. Is this not what fingerprint examiners do? Of course we do not create the impressions we examine, but we do look carefully at one impression, store an accurate image of it in our visual memory, then look at the other impression, compare the two and decide whether they match closely enough for us to make an identification. Artists use the ability to store an image in the memory and compare it with another to create works of art and we use it to examine fingerprints.

If Leonardo da Vinci used the same ability in painting the Mona Lisa and he did when he made his sketches of flying machines and submarines; if this was the same ability that Bewick used when he carved his mark into wooden stamps, and Grew used in his anatomical drawings of friction ridges; if this is the same ability that is used in fingerprint comparison; aren’t we artists?

A Psychological Model of the Fingerprint Comparison Process.

Recognition is a natural function of the human brain. Every day we see objects, people, faces, we hear sounds, we observe behaviour. Our sensory organs encode this input into nerve impulse patterns. Our brains automatically process these impulse patterns, comparing them with all the stored examples in our memory to try to match them up. When a match is found the input is recognised1.

“I see a man. It’s my friend Ben. I hear him laughing. I know he is amused”.

When no match is found the brain seeks out a tag for that object/person/sound/behaviour/etc before it is stored in the memory. The tag could be a name, the time, the place or any other associated sensory input. The tag is the means by which the memory is recognised when it is remembered. Tagging is not a completely subconscious process however. Subconsciously attached tags can be ineffective and loose. They are sufficient for short term recognition but may not survive the transition into long term memory. Rehearsal is a common and effective means of improving long term memory2. It reinforces the attachment of tag to memory. Another well known memory technique is the mnemonic. Making up a rhyme or story involves conscious thought and reasoning. This not only reinforces the attachment of the tag but it makes the tag itself more distinctive and more effective. If no tag is attached to a memory, or the tag is not effective, then recognition cannot occur. The memory may be recalled but without a tag it cannot be recognised.

This process has been likened to an AFIS computer system. A set of fingerprints is scanned in, encoded, searched through the database and either matched to a known set or filed in the database with its own unique reference number so that it can be matched with subsequent sets of prints from the same person when they are searched3. The tag in this case is the unique reference number assigned to the prints. That number allows the operator to link the prints with other data and to find out who the prints belong to.

This model of the psychology of recognition can be applied to how a fingerprint examiner works. At the start of a search and compare exercise the examiner observes a feature of the latent print and forms a mental image of it. The examiner’s brain automatically compares this mental image with all the images of fingerprints stored in the memory attempting to recognise it. Occasionally, with some examiners, recognition occurs at this stage. They disappear into the files and return seconds later with the matching form. A “Memory Ident”. To some this ability may seem amazing but it is explained by the model as the effective tagging of long term memories leading to efficient recognition. That feeling that most of us get from time to time, that we’ve seen a print before but we can’t remember when or where, is an untagged or ineffectively tagged memory.

Most of the time the latent print remains unrecognised at this stage and is tagged as “What I’m looking for.” and memorised. Most fingerprint comparison takes place in short term memory4 so this loose tagging suffices. However, there are techniques which can assist the examiner in remembering the mental image of the latent print. The sequence of features in a target group can be rehearsed mentally or verbally. Drawing the target is also a form or rehearsal. Assigning names to features turns the sequence into a mnemonic. It has been noted that the more imaginative the name the easier it is to recognise the feature (fig. 1)3, this is because the mental reasoning needed to associate the name with the feature increases its strength as a memory tag.
In the search for the latent print each inked print is scanned in turn, observed features are searched through the memory, until something matches with the memorised target and is recognised as “What I’m looking for”. During the one-to-one comparison of latent and inked prints that follows this whole process is repeated with all features of the latent print being memorised and then looked for in the inked print.

We can fit this whole process into an expanded AFIS analogy (fig. 2). The latent print is scanned in, encoded and searched through the tenprint database. The memory ident is a latent-tenprint hit. If the latent print is not identified it is filed in the unidentified latents database with its own unique reference number. The inked prints are then scanned in, coded and searched through the unidentified latents database. An ident at this stage is a tenprint-latent hit. This may seem to be back-to-front at first but remember this; it is the print you are looking at that is being searched through your memory database where you have filed “What you are looking for”.

Figure 1. Imaginative names for features can aid recognition.
a) bowtie, b) handshake, c) banana, d) chicane

Figure 2. The expanded AFIS analogy.

The Science of Fingerprint Examination.

As described above, fingerprint comparison is a mental process. Just like any other mental or physical task, all it takes to effectively apply the innate abilities of observation, memory, comparison and recognition to the tasks of comparing fingerprints is operational training and practice. No knowledge of why fingerprints are unique and persistent, of the history of fingerprint or of law is needed. I know this is an over-used analogy but you don’t need to know how an internal combustion engine works to drive a car. You don’t have to know who Benz and Ford were or what they did. You don’t even have to know the Highway Code to make a car move. All you need to know is what the pedals do, when and how to change gear and how the steering wheel works. You need to practice if you’re not going to stall the engine, spin out of control, or crash into a brick wall. You do, however, need to know the Highway Code if you want to drive on the public road. Moreover, if you’re going to explain to a Coroner how a manufacturing fault caused a fatal accident you need to know your stuff. You need to be an ‘expert’.

Fingerprint comparison, an art, skill, craft1 or mental process, is only one part of the examination process described by Ashbaugh by the acronym ACE: Analysis, Comparison, Evaluation2,3. So can we say that fingerprint examination is a science?

Once again let’s start with the origin of the word. It’s Latin again, lucky me.

Sc/io –ire –ivi –itum vt. know; have skill in.

Scienti/a –ae f. knowledge: skill.

Sci/ens –entis pres.p. scio a. knowing; versed in. –enter ad. expertly.4

Clearly we have some justification here to describe any skill or expertise a science, but that’s ancient Latin not modern English.

The concept that science is knowledge persists throughout all of the English dictionaries I studied. Collins English Dictionary, 21st Century Edition, lists six.

1 – The systematic study of the nature and behaviour of the material and physical universe, based on observation, experiment and measurement, and the formulation of laws to describe these facts in general terms.

2 – The knowledge so obtained or the practice of obtaining it.

3 – Any particular branch of this knowledge: the pure and applied sciences.

4 – Any body of knowledge organized in a systematic manner.

5 – Skill or technique.

6 – archaic. Knowledge.5

Fingerprint identification rests on a foundation of years of scientific research. We acknowledge people such as Bidloo, Purkinje and Galton as great scientists of their times and recognise how their work can be applied to our discipline. Those characters from our history not traditionally recognised as scientists worked in a scientific manner. Herschel’s demonstrations of persistence were simple scientific experiments. Henry’s classification system uses a mathematical algorhythm to organise fingerprints in a systematic manner. That, by the definitions above, is science.

To fully understand the fingerprint examination process and to explain how and why it works to other people the examiner must have an extensive breadth and depth of knowledge.  The two fundamental principles of friction ridge identification are uniqueness and permanence. The understanding of how The Law of Natural Uniqueness is applied to friction ridges through The Theory of Differential Growth stems from knowledge of how friction ridges develop in the foetus (embryology). Permanence, or persistence, is rooted in the structure and growth of the skin tissue (histology). Proper application of the comparison process requires an understanding of how the brain works (psychology). Accurate analysis of distortion relies, in part, upon knowledge of how a flexible curved surface deforms when it comes into contact with a hard plane surface (geometry). Some latent prints can be made visible by fluorescence or by the application of powders (physics). Some Latent prints could not be developed without knowing the constituents of sweat (physiology) and how they react with other chemicals (chemistry). I could go on but there is one word that will cover every applicable science that relates to fingerprints. The scope of Ridgeology3 is to draw together all related aspects of the pure sciences under one umbrella term, and to apply them to forensic friction ridge identification. Some question the need to make up a word now to describe a practise over a century old6, but new words are being invented all the time, to describe new concepts. Only time will tell whether the word itself survives, but the concept is sound. Ridgeology is the science of fingerprint examination.

I fear, however, that we may all be missing the point in this debate. Television drama series such as ‘CSI’ are raising the general public’s awareness, and their expectations, of our work. When the people I meet hear that I work in fingerprints they reveal their preconceptions. To them I am a forensic scientist. DNA profiling is recognised as a scientific identification method. The trust that people place in DNA profiling rests in its science. If we do not meet the expectations of the public we will not be trusted. In courts worldwide lawyers and scientists are beginning to question all aspects of our work. Challenges are being made seeking to make fingerprint evidence inadmissible on the basis that is not scientific. How would these challenges fare when the experts themselves deny that they are scientists? In an increasingly technological and scientific world no-one can afford to stand still. Advances and improvements must be made. Knowledge and understanding must be increased or we will not survive.

Just as Darwin concluded that changes in the demands of the environment, competition for food and predation were the causes of evolution by natural selection; I conclude that the expectations of the police, the judicial system and the public, competition from other forensic identification sciences, and the challenges put forward by our critics will result in the evolution of the fingerprint service into a widely accepted and self-acknowledged scientific profession.

Acknowledgments and References.

Is Fingerprint Examination an Art?

My thoughts on the place of artistic talent in fingerprint examination were inspired by the teaching of Pat A. Wertheim, who relates his experiences and thoughts in “The Ability Equation.” Journal of Forensic Identification, 46(2), 1996.

A Psychological Model of the Fingerprint Comparison Process.

Thanks to the examiners who came up with the names for the features in figure 1, whose names are unknown to me.

1. Ashbaugh, David R. “Quantitative-Qualitative Friction Ridge Analysis, An Introduction to Basic and Advanced Ridgeology” CRC Press LLC, 1999.

2. Weinman, John BA PhD, “An Outline of Psychology as Applied to Medicine” 2nd ed. IOP Publishing, 1987.

3. Wertheim, Pat A. Training course on “Advanced Ridgeology Comparison Techniques”, 2001.

4. Ashbaugh, David R. “Ridgeology” Journal of Forensic Identification, 41(1), 1991.

The Science of Fingerprint Examination.

Thanks to the participants of the long running debate on this topic, especially to those whom I asked personally for their opinions.

1. Leadbetter, Martin, “There is no Crisis” Fingerprint Whorld, 29(111), 2003.

2. Ashbaugh, David R. “Quantitative-Qualitative Friction Ridge Analysis, An Introduction to Basic and Advanced Ridgeology” CRC Press LLC, 1999.

3. Ashbaugh, David R. “Ridgeology” Journal of Forensic Identification, 41(1), 1991.

4. Collins Gem Latin-English English-Latin Dictionary, William Collins Sons & Co. Ltd. 1957

5. Collins English Dictionary, 21st Century Edition, William Collins Sons & Co. Ltd. 2000

6. Leadbetter, Martin, “Third Level detail” Fingerprint Whorld, 29(111), 2003.

This article was originally published in Fingerprint Whorld, and was made available to CLPEX with the permission of the editor, Dave Charlton.



"CSI Miami: A double shooting at a nightclub is the first case worked on by new fingerprint tech Ben McFadden. Ben is young and hot and can't believe that Caleigh won't go out with him."

Submitted by Jon Stimac: "(I never thought I'd see - or read about - a "soap opera" specific to forensics!)"
Copied on 8-29-03 from http://www.filmjerk.com/new/article602.html


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