CLPEX Chat Board

I just had a student call to ask me about a question she had on a test she was taking.

The essay question was:

There are five general types of fingerprint patterns. Name and describe each and tell what percent of the population has each type.


The answer given by the instructor....hope you're sittin' down.......

plain arch 5%

tented arch 5%

whorl 30 - 35%

finger loop 65%

and my personal favorite the

THUMB LOOP also 65%

I had just HAD to share!!

Thumb Loop?

Sounds like some kind of torture device.

Hmmm

How can you expect students to be able to handle mathematics when the teacher certainly can't.

The population adds up to at least 105% (not including the thumb loop!)

I wonder if "finger" and "thumb" are being used as a dumbed down version of "ulnar" and "radial" to denote the slope.

Still, the maths is very suspect

I am the student representative for the course that I am on and I have to say that the level of teaching in fingerprinting was disappointing to say the least. The best lesson we had was when a gentleman came from the Fingerprint Bureau in Birmingham to give us a talk.

I wish he would come back every week.

Can I ask what you would recommend that I read to help me learn certain aspects of fingerprinting.

A) The identification process and writing the reports that go with it
B) The science behind the latent fingerprint, what is the composition of sweat etc.
C) How to get a job (well I can but hope!)

Any advice would be helpful

Hi Emma

For reading, I would recommend beginning with David Ashbaugh's original paper, "Ridgeology." It was published in a number of periodicals and should be easy to find. Follow that with his book, "Quantitative-Qualitative Friction Ridge Analysis." This is the best general current information on the science behind what fingerprint examiners do and why they do it.

For history, Colin Beavan's book, "Fingerprints," is a wonderful read. Another book with a fascinating discussion of fingerprint history is Simon Cole's book, "Suspect Identities," if you can get past the negative attitude that pervades his writing.

This forum (at least, the serious discussions) has some of the best information available for the understanding of what fingerprint examiners do. Because it is presented in conversational form with dissenting views, you can see all sides of the current issues. Even the latest research can be gleaned here before its actual publication because the researchers continually post and add their comments to the threads, and many of the threads are started by our best and brightest researchers. For the most current topics of discussion and ideas in the business, you simply cannot beat the information you read here.

As for getting a job, my advice is to seek out internships with fingerprint bureau. Don't restrict yourself to those within driving distance of your home, but search far afield. In the absence of an internship, volunteer with a crime laboratory or fingerprint bureau. I know the cost to you will be considerable for going through an internship, even more so as a simple volunteer. There will be rent, transportation, etc., but consider the cost as just another form of expense for your education. And you will get stuck with all of the dirty, least productive work in the laboratory (mixing chemicals, washing glassware, etc.) But you will become intimately acquainted with the work itself, as well. In my agency, we almost always hire former interns and volunteers in preference to other applicants.

Thanks for your advice. I have Ashbaugh's book and have read his papers. I have also read some of Simon Cole's papers and I certainly agree with the the comments about his negativity, I always feel agreived when reading his papers as if I was a fingerprint expert myself, not that I am in any way shape or form.

Does anyone know if there are any studies being undertaken at the moment about the uniqueness of fingerprints. From what I read, Cole does not agree that a hundred's years worth of examinations and never finding two identical fingerprints as evidence enough of uniqueness.

Anyway, thanks again.

In court, Dr. Simon Cole does not dispute the uniqueness of fingerprints. He readily agrees that whole fingerprints are unique. And he testifies, when pressed, that he believes the methodology we use is probably reliable. But he remaines wedded to the idea that until we have conducted validation studies to PROVE the reliability of ACE-V and establish an error rate associated with it, the use of fingerprints in court should be suspended. I agree with him that we need those validation studies. There are several noted researchers working on such studies from different approaches. But we shouldn't "throw the baby out with the bathwater." His testimony is a far cry from his published material. In court, he is actually a very weak witness for the defense when challenging fingerprints and even seems to tip the scales in favor of the prosecution for the admission of the fingerprint evidence. His criticism has merit, but his written articles go too far. Fortunately, his testimony does not come across the way his writing does.

EmmaC
If you have some room in your schedule, may I suggest a class in statistics and a class in cognitive psychology (how people perceive, reason, and remember). Both are hot topics in many of the forensic challenges.
I think all of the briefs for Commonwealth v. Patterson, the Mass. case on simultaneous/cluster prints is on CLPEX -- those will give you a feel for some of the hot issues in challenges to fingerprint IDs and, by extension, other forensic areas.

As to Cole, I think his major point has to do with partial latents. I don't think anyone is arguing uniqueness and permanence as to good quality complete prints. The argument starts when one gets into poor quality prints of small areas of a finger.

Fingerprint Residue
The components of sweat transferred to different surfaces may differ from that found on the surface of skin. Studies that have analyzed the chemical makeup of sweat examine the content in its purest state. This does not take into account the variety of contaminates picked up by friction ridge skin during ordinary, everyday use. The law enforcement community began to examine latent print residues critically and scientifically in the late 1960s.

Many environmental contaminants have been detected both in analyses of sweat and fingerprint residues. Caution must be exercised in determining whether such compounds might indeed be contaminants or as compounds derived from an endogenous source (ingested or absorbed). There may be some overlap between compounds present in the contaminant and ones from an endogenous source, which could lead to overestimates of the quantity of such compounds. (Think hair gel, makeup, perfumes, food residue, nicotine, etc.)

Latent print residue is a complex mixture of many different types of substances. Derived primarily from the three secretory glands (eccrine, apocrine and sebaceous), sweat is deposited on virtually every surface touched by hands.

For years, fingerprint scientists have sought new methods or tried to improve existing methods for the visualization of latents. At an overall level, all successful methods of latent print enhancement are targeted toward some known component of latent print residue. Although a complete understanding of all individual components in latent print residue and their quantities has not been attained, many of the compounds present are known. Some methods target water-soluble components while others target lipids. The best method, then, depends on the latent, the surface, and any environmentally induced changes. At another level, enhancement methods exploit the chemistry of latent residue components and their potential reactions and interactions.

For more information read Advances in Fingerprint Technology - Second Edition