T H E
D E T A I L
Monday, December 8, 2003
BREAKING NEWz you can
compiled by Jon Stimac
Rubber Finger Could Have Helped Frame Convicts -
SUNDAY TIMES, AU - Dec. 3, 2003
...investigators in a 1982 swindle could have used a rubber finger to
create the fingerprint that implicated convicted brothers...
Handprint Points to Conviction -
DELAWARE COUNTY TIMES, PA - Dec. 3, 2003
print in conjunction with suspects statement that he had never been in the
victims apartment were the key to conviction...
Fingerprint Trail Ends Life on the Lam -
TRI-VALLEY HERALD, CA
- Dec. 3, 2003
changed his name twice, started a family and moved to Texas, but he could
not erase his fingerprints...
Sprays Catch Elusive Fingerprints -
ABC SCIENCE ONLINE, AU -
Nov. 28, 2003
fingerprints might soon be lifted from rough surfaces...
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.
Last week, Paul Brannon
brought us instructions on building a CA fuming chamber
on a budget. This week, Craig Coppock relates some thoughts on minimum
information in fingerprint identification.
Minimum Information And Fingerprint Identification
The concept of forensic identification is based on the evaluation of
information. With fingerprint identification, information is analyzed and
compared to available exemplar and other sources to determine if the impressions
in question originated from one and the same source. Fingerprint identification
information sources are generally divided into three levels. Level one is macro
detail such as ridge flow and pattern type. Level two is the Galton
characteristics, or points of identification, such as bifurcations and ending
ridges. Level three information is contained in the shape and structure of the
ridges themselves. Of course, multiple types of forensic information can be
found in a fingerprint. Not only can all three levels be present, but other
information can also be available such as DNA, chemical information, as well as
information contained in the distortion of the print itself. These additional
sources of information are not considered as formal levels of comparison, yet
they may offer additional means to allow for individualization and/or evidence
For many decades, print examiners have been asked during testimony; “what the
minimum point requirement is for print identification?” At one time this was a
acceptable question since many countries required a minimum number of Galton
characteristics before an identification was legally accepted. However, there is
no statistical foundation for a minimum point requirement because examiners
perform both quantitative (level 2) and qualitative (level 3) examinations.
Clarity is based on multiple inter-dependent factors of distortion, which in
combination are thought by many examiners to be too complex to be effectively
quantized for statistical analysis. The detail being analyzed in a fingerprint
comparison is potentially the most multifarious of any forensic science.
An understanding of the information being analyzed and how it is being analyzed
is the key to deducing its value for identification purposes. Information is
always found in related groups of varying content. This can be thought of as
a principle of minimum information. A single bit of information is not
possible due to the fact that at the very least it will have a relationship with
one other bit of information such as its opposite value. The very fact that an
identifying characteristic is present is information. Its minimum opposite value
would be the fact that we know it is not missing. With this reasoning the lack
of information also has value. Additional information allows further information
correlation at relative quality and quantity values. Information can be
evidence. Its proper evaluation and correlation is imperative.
Thus, the discovery and documentation of a single characteristic generates more
information than the simple fact of that characteristic’s existence. With
comparative analysis, it generates information on its relative position, size,
shape. etc. Uniqueness, such as that of a Galton characteristic, is simply a
large grouping of information. Hence, uniqueness can be defined as; sufficient
information that allows for a relative distinction or possibly an
With fingerprint identification a variable threshold for individualization can
exist based on quantitative and qualitative information values. With threshold
comparisons this grouping aspect of discovered information is more noticeable as
the examiner focuses their attention on the limited details. Threshold
fingerprint identifications are based on the evaluation of groups of related
information of varying quality. Accordingly, there is never a single bit of
information that would make the difference between a conclusion of
individualization or non-individualization.
Most statistic models that support the validity of fingerprint identification
have been limited to specific levels of detail such as Galton points. The
ability to quantify and therefore consider third level detail in a statistical
model would further strengthen that model. However, even if the complexity of
statistical models involving third level detail could be overcome we would still
encounter the minimum information principle and its relative nature.
Craig A . Coppock
Forensic Specialist CLPE
Spokane County-City Forensic Unit
To discuss this Weekly Detail, log on to the CLPEX.com
More formal latent print discussions are available at
FUNNY FINGERPRINT FIND
"Large databases are being built up of fingerprint data and now DNA
data. The acuracy of this data is at best questionable. Fingerprints are
measured at 16 points. From this you do not get 16^16. I think that if you
measured fingerprints to an infinite acuracy you may find the theoretical
infinate number of fingerprints required to sustain the myth that no 2
fingerprints are the same but here in the real world we measure a finite number
of points and therefore have a finite number of prints and as the database
reaches that number there must be mistakes. The mistakes are already happening
with DNA and because this evidence is perported assumed to be infallible
innocent people are being arrested. If this evidence was only used to support
other evidence I would see it as a good thing but when it is used as the only
evidence then it is very bad. I think that in the future this DNA witch hunt
will be seen for what it is but for now innocent people will be caught up with
Contributed by Steve
Success and Feedback
You can help already effective employees improve by asking them this question
after they complete an assignment:
"What did you do the best?"
They get to brag a little and review their successes. Let them know that
you noticed and appreciated their good judgment and effort.
Timely feedback is particularly important for Generation-X employees. They
grew up with computers that quickly told them when they did something wrong:
misspelled a word, incorrectly downloaded a file or failed to destroy the
villain in a game.
If you put off giving negative feedback to Gen-Xers they often assume they're
doing well. And their reaction to your criticism - when you finally get
around to it - will be "Why didn't somebody tell me?"
So, don't put off critical [positive or negative] comments until a formal review
or coaching session. Give them the kind of quick response they've come to
expect from technology.
Dorothy Leeds, McGraw-Hill, and
Your Valuable Employees, Morrie Shechtman, Facts on Demand Press,
via Communication Briefings, September 2003, 800.722.9221, briefings.com.
Feel free to pass The Detail along to other examiners. This is a free
newsletter FOR latent print examiners, BY latent print examiners. There are no
copyrights on The Detail, and the website is open for all to visit.
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Until next Monday morning, don't work too hard or too little.
Have a GREAT week!