T  H  E      D  E  T  A  I  L

The Detail Archives

Discuss This Issue

Subscribe to The Detail

Monday, October 22, 2001

Welcome to the eleventh "Detail," a weekly e-mail newsletter that greets you 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.

BREAKING NEWz you can UzE...

Another 40 or so latent print related articles are now organized and available on the Articles page.  These comprise articles by authors (alphabetically) M-Z on the Southern California Association of Fingerprint Officers bibliography which reside on the SCAFO website.  The articles were made available by SCAFO, copied and organized for the CLPEX Articles page by Mary Drews, and updated on the site this week.  Other webmasters, please feel free to link directly to this page.  Again, thank you to all persons whose efforts have lead to the direct, "one-click" availability of these articles for latent print examiners!  

Scott's Fingerprint Mechanics...  A new, unread copy available for $80 at the CLPEX.com bookstore. (first e-mail get's it!)


The results are in!

About 50 respondents represented 15 states and two other countries in the following results:

Latent print examiner respondents were about 20% sworn, 80% civilian.

10% said their departments employed both.

More sworn latent print examiners were employed in city departments than county, state, and federal combined.

Even with the above, over twice as many respondents from CITY departments are civilian latent print examiners rather than sworn.

Less than 10 percent of county, state, and federal latent print examiners are sworn.


Man... that sounded like a bad logic puzzle!!


We are currently in the middle of a series of Details regarding whether or not the principles and methodologies of friction ridge skin analysis constitute scientific practice.  As we saw last week, the issue of there being "no standards" in the field of fingerprint examination can be easily addressed when we realize that the ACE-V methodology is used throughout the world, even though the exact words "Analysis" "Comparison" "Evaluation" and "Verification" may not be employed by every agency.  We also looked at how the entire ACE-V methodology is objective, with the exception of a portion of the evaluation phase.   Visit the CLPEX.com archives page for the entire article.

This week we are addressing whether or not identifying partial distorted latent prints is reliable and has been tested.  A portion of this question deals with the uniqueness contained within a print.  By using the word "partial," those raising these questions seem to misunderstand biological uniqueness.  The fact is, half of unique is still unique.  There are no levels of uniqueness.  As we saw in earlier Details, uniqueness begins smaller than a single ridge and builds from there, not the other way around.  Besides, I would argue that every print is partial.  Even fully-rolled inked prints do not contain all the detail in the tip of the finger.  Those who argue against the science of fingerprints are mixed on the concept of partial.  I believe they all admit uniqueness across an entire fingerprint (some grudgingly), and most admit biological uniqueness even in small areas of print.  But some even want to see scientific "proof" of this.

When we look at the concept of distortion, things get fuzzy.   (Sorry... I couldn't resist  :-)~

As with all prints being "partial," we also see all prints containing some sort of distortion.  To argue that distortion causes the science of fingerprints to be invalid is quite a stretch.  Even ideal inked prints contain distortion.  This is due to the transfer of three-dimensional detail into two-dimensional detail.  Not all the detail will ever transfer, because a dimension is being lost.  Therefore all fingerprints, latent or inked, have some level of distortion.

So we see that all fingerprints are partial distorted prints.  At some point, either the size of the print (quantity) or the distortion of the print (quality) will make individualization from that print impossible, but that determination is a subjective one by the examiner, and does not enter into the identification process.  Allow me to clarify this point; the subjective decision of the examiner as to the sufficiency or non-sufficiency of a latent impression for identification purposes does not affect the objectivity of the identification process. (ACE-V)  The determination that a print is "of value" happens before ACE-V and therefore does not affect the objectivity of the methodology.  We mentioned last week that on occasion, a thorough analysis of the latent print will sometimes cause the examiner to re-evaluate the print and determine that it is not of value for identification purposes, but in that situation the print would not be identified anyway, and the methodology would still remain objective.

So to conclude, all latent prints are partial and all latent prints are distorted.  The determination of sufficiency is a subjective determination based on a number of factors, including the examiners ability; training, experience, talent, motivation, daily variables, etc...    If a latent print is determined to be "of value," then either identification or elimination will result (if ideal known exemplars can be obtained.)

The issue of testing can be addressed in several ways.  The government in the Daubert decision (U.S. v. Mitchell) chose to highlight the fact that "...the ACE-V process and, in particular the opinion of the sufficiency of the information present, which completes the opinion of individualization, can easily be tested by the review of the evidence by other experts."  Another way to address testing is to offer the fact that billions of comparisons that have been conducted throughout the world for over a century, and not one "distorted fragment" of value has ever been found to contain the same detail as a print from another source.  Still another way to address this issue involves the astronomical statistical calculations involved in the 50K X 50K study mentioned in the second Detail.  Each of these concepts can be used to address testing the science behind the identification of "partial, distorted latent prints." 

Next week we will probably be completing this short series of Details defending our science with a discussion of the fingerprint / DNA comparison and the use of statistics in the identification process.  I say probably because I will be "on the road" all week, and I plan on being able to update the site and send the detail; but my new laptop has not arrived yet.  So we'll see.  We may have another abbreviated issue next week and finish up the week after.

If you would like to give YOUR input on the identification of "small distorted fragments," or offer another angle from which to address this issue, please make your way to the discussion forum and express your viewpoints.


Cummins and Midlo (from last week) sold! This week I offer an as-new Scott's Fingerprint Mechanics for $80!  (first e-mail gets it!)  Receipt provided with order for agency reimbursement, if applicable.

Added another 40 latent print-related articles to the Articles page.  If you know of other online articles that are not referenced, your help in building the links would be greatly appreciated!  If you are surfing a particular topic, please consider copying and pasting links to online information into an e-mail for me to utilize when adding to the Articles page.  Your help would be greatly appreciated by all!  Thanks again, Mary Drews, for doing this with the SCAFO bibliography!

Feel free to pass the link to The Detail along to other examiners. This is a free service FOR latent print examiners, BY latent print examiners. There are no copyrights on The Detail, and the website is open for all to visit.

If you have not yet signed up to receive the Weekly Detail in YOUR e-mail inbox, go ahead and join the list now so you don't miss out!

Until next Monday morning, don't work too hard or too little.
Have a GREAT week!


The Detail Archives

Discuss This Issue

Subscribe to The Detail