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