Good morning via the "Detail," a weekly e-mail newsletter that greets
latent print examiners around the glyobe 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
Last week, we reviewed the
new IAI requirements for latent print certification. This week, we will
read an discuss an article that was just published in the National Association
of Criminal Defense Lawyers publication.
THE MYTH OF FINGERPRINTS
There was a time – not very long ago – when we considered fingerprints to be the
gold standard of scientific evidence. We assumed that fingerprint analysts were
virtually infallible. Defense counsel not only rarely challenged the
admissibility of fingerprint testimony; but on many occasions they also
stipulated to the admission of the findings of fingerprint examiners.
However, in the past few years we have become more skeptical about the opinions
of fingerprint examiners. The initial shock came when proficiency tests
revealed a substantial margin of error, including false positives, in examiners’
findings.1 Finally, in 2002, the forensic community was stunned when
Judge Pollak excluded fingerprint testimony in United States v. Llera Plaza2,
before changing his mind. 3
To date, most of the attention has focused on the question of the
reliability of the process by which the fingerprint expert “matches” the inked
impression with the latent print found at the crime scene. Thanks in large part
to Robert Epstein, we now appreciate that even if each person’s fingerprint is
unique, the examiner has to work with incomplete, somewhat distorted impressions
of the fingerprint. Simply stated, it is a logical fallacy to leap from the
premise of the uniqueness of fingerprints to the conclusion of the reliability
of fingerprint comparison. That fact may enable the defense counsel to mount an
effective weight attack on prosecution fingerprint testimony even when the judge
rules the testimony admissible.
However, it is critical to realize that in a given case, fingerprint testimony
can have another Achilles heel. That weakness is the nature of the image which
the examiner compares to the inked impression. You should not assume that the
image being compared is the original image discovered at the crime scene. In
many cases today, the police have used computer technology to alter the original
image. Indeed, in some cases, the image compared to the inked impression is one
which the police have in a very real sense created!
The use of computers to manipulate images of fingerprint impressions is
proliferating. The practice began in the early 1990’s. However, it has become
so widespread that CBS News recently aired a 60 MINUTES II segment devoted to
the practice. The segment was entitled “The Hidden Clue.”4 During
the segment, reporter Jim Stewart enthusiastically announces that “[d]etectives
now have a new tool for cracking even the toughest of cases. Known as digital
fingerprint enhancement, it’s become the silver bullet among police forensic
units all across the country…”
Based on our conversations with forensic personnel, including the staff at the
New York Police Department (NYPD), the Miami-Dade Police Department (MDPD), and
the Los Angeles Sheriff’s Department (LASD), perhaps 20 percent of American law
enforcement agencies already have in-house technology for “touching up” or
“embellishing” the fingerprint image found at the crime scene. 5
What exactly does “touching up” entail?
Image enhancement. In some cases, that expression means image
enhancement. 4 Image enhancement is subtractive. The process relies
on computer software designed to improve the sharpness and contrast of a
photograph by eliminating background patterns and colors. Before a normal
photograph can be enhanced, the photographic image is digitized. 7
Digital images are composed of millions of tiny dots referred to as “pixels.”
Then, based on degradation models developed in research, the software
manipulates the pixels to filter out graininess and improve brightness and
Image enhancement has been adapted for use in fingerprint analysis. By way of
example, analysts have used the process to remove patterns from original latent
fingerprints, including the background on a check, the dot pattern on newsprint,
and the weave pattern on material that would otherwise interfere with
identification. They have also resorted to the process to improve the quality
of latent prints lifted off blood stained fabrics and other difficult surfaces.
Image creation. Although image enhancement can be controversial, even more
dramatically in some cases fingerprint analysts are now creating the image that
is eventually compared with the inked impression. Consider the case of
People of the State of California v. Gerald F. Mason. The case involved a
murder committed 45 years ago in El Sugundo, California. The police had found
latent impressions on the steering wheel of a stolen vehicle involved in the
case, but until the advent of computerized fingerprint technology the police
could not use the impressions. The prints were partials. The police assumed
that they belonged to the same person, but none of the prints was complete
enough to permit identification.
All that changed when the technology became available. Initially, the police
enlarged the partials. They then placed the enlargements on plastic
transparency paper. Next, they used the transparency papers to in effect place
one partial on top of another – to create a thumbprint that could be run through
a database. The El Sugundo Police Department lacked the technology to do so,
but they persuaded the Los Angeles Sheriff’s Department to enter the thumbprint
into its computer and execute an Automate Fingerprint Identification System
(AFIS) search for matches.
The computer identified a number of potential candidates. Candidate number ten
was Gerald F. Mason, a South Carolinian. Mason was the right age to have
committed the murder, and he matched the physical description of the killer.
The subsequent investigation uncovered other evidence incriminating Mason.
Mason was eventually extradited to California where he confessed to the
killing. Given the confession, the police probably got the right man. However,
the noteworthy aspect of the case is that the fingerprint image that was
compared to the database was one the El Segundo police had literally created.
LEGAL IMPLICATIONS OF THE TECHNOLOGY
In any case in which the prosecution claims that the police laboratory has
compared the defendant’s inked print to “a crime scene latent,” you can no
longer assume that the image compared to your client’s inked print was the
original crime scene print. That image may have been significantly altered or
even manufactured by the police. The advent of this new technology has
implications for every stage in the criminal justice process.
Pre-trial discovery. Demand to know whether the image compared to your
client’s inked print was the original impression found at the crime scene. If
not, how did the police obtain – or generate – the image that was compared? If
that image was created by computer, which software was used to produce the
image? What research has been done to validate the accuracy of that software
program? In applying the procedure, did the police observe the guidelines
recommended by the Association for Information and Image Management (AIIM)?
Insist that the police produce the original crime scene impression. If the
original impression is no longer available, inquire as to what happened to it?
Did someone destroy it? If so, who did so and why?
In Limine motions to exclude fingerprint testimony. This Achilles heel
provides a basis for excluding fingerprint testimony apart from a generalized
Daubert attack on the reliability of the comparison process.
To be sure, a Daubert attack is a possibility. There have been only a
few published opinions dealing with image enhancement technology. 9
Most jurisdictions have yet to pass on the admissibility of images produced by
this process. Mount a Daubert challenge. Remember that the question is
not the general validity of the image enhancement theory. Rather, the question
is the accuracy of the particular software which the police laboratory employed
to enhance or create the image in question. 10 Under Daubert,
the prosecution must establish “appropriate validation” for the validity of that
In addition, consider an alternative Federal Rule of Evidence 702 attack. As
amended, in 2000, Rule 702 now mandates that the proponent demonstrate both that
“the testimony is the product of reliable principles and methods” and that “the
witness has applied the principles and methods reliably to the facts of the
case.” Prior to that amendment, prosecutors sometimes argued that proof of
proper test procedure was not a required element of the foundation for expert
testimony. 11 They contended that violations of correct test
protocol cut to weight rather than admissibility. However, the 2000 amendment
forecloses that argument. As previously noted, AIIM has developed guidelines
for using imaging technology. If the police ignored or deviated from those
guidelines in the instant case, cite the amended version of the statute and urge
the trial judge to exclude under Rule 702.
If the original crime scene image is no longer available, press a best evidence
rule objection. There is a strong argument that the enhanced or generated image
is neither an “original” under Federal Rule 1001(3) or even a “duplicate” under
On their face, both subdivisions require a showing that the exhibit produced in
court “accurately” reflects the original, raw evidence. In the case of image
enhancement, the computer has subtracted pixels and changed the image. It is
undeniable that the enhanced image differs from the original. At the very
least, the enhanced image is an incomplete version of the original image. In
the case of a created fingerprint, it is even clearer that the exhibit proffered
in court differs from the partials found at the crime scene. If the computer
manipulated exhibits are neither originals nor duplicates and the prosecution
cannot establish an adequate excuse for the non-production of the original
image, Rule 1002 bars the fingerprint evidence.
Weight attacks at trial. To begin with, be conscious of the way you refer
to the exhibits. Refer to the original crime scene image as “the real
evidence.” In contrast, characterize the computer “manipulated” image as one
the police “created” or “manufactured.”
Be visual. Introduce the original image.
If the prosecution was foolish enough to neglect to introduce the original,
remind the jury that they have the “real evidence” only because you bothered to
present it to them. Contrast the original image with both the defendant’s inked
impression and the manipulated image. Point out all the evident differences
among the three. Doing so not only calls into question the reliability of the
ultimate opinion that the crime scene fingerprint is the defendant’s. Even more
importantly, doing so can call into question the credibility of the prosecution
If there are marked differences between the original image and the computer
manipulated image, some jurors may begin to think that the prosecution experts
have strained to mislead them. Some may suspect that the prosecution has
attempted to “manipulate” them just as the technician manipulated the pixels.
Computer manipulation of fingerprints is only the tip of the iceberg. Similar
techniques are being used in the analysis of blood spatters, toolmarks,
bitemarks, footwear impressions, gunshot residue, tire tread impressions, hair,
fiber, and videos. This is the summer of computerized make-believe in The
Matrix Reloaded and Terminator. Make certain that the jury
understands the difference between the courtroom and the theatre. In the
theatre, we enjoy fantasy; but in the courtroom, we want and need fact.
Grieve, Possession of Truth, 46 Journal of
Forensic Identification 521 (1996); Starrs, Forensic Science on the Ropes: An
Upper Cut to Fingerprinting, 20 Scientific Sleuthing Rev. 1 (Wint. 1996).
Then Robert Epstein released his influential article, Fingerprints Meet Daubert:
The Myth of Fingerprint ‘Science’ Is Revealed, 75 Southern California Law
Review 605 (2002).
179 F.Supp.2d 492 (E.D.Pa.2002)
188 F.Supp.2d 549 (E.E.Pa.2002).
A written version of this segment [was obtained] on
the internet at http://uttm.com/stories/2002/11/19/60ll/main530029.shtml.
Several departments use software developed by PC
Professionals. PC Professionals posts its client list at http://pcprosusa.com/clients.html.
See generally 2 P. Ginnalli & E.
Immwinkelried, Scientific Evidence 25-6.1 (2002 Supp.).
G. Joseph, Modern Visual Evidence 8-22 (1999),
You can contact AIIM at its International
headquarters. 1100 Wayne Avenue, Suite 1100, Silver Spring, Maryland 20910.
Its phone number is (301) 587-8202, its fax number (301) 587-2711, and its
Nooner v. State, 907 S.W.2d 677 (Ark, 1995); Dolan
v. State, 743 So.2d 544 (Fla.Dist.Ct.App. 1999); Wagner v. State, 707 So.2d 827
(Fla.App. 1998); State v. Hayden, 950 P.2d 1024 (Wash.App. 1998).
Risinger, Defining the ‘Task at Hand”:
Non-Science Forensic Science After Kumho Tire Co. v. Carmichael, 57
Washington & Lee Law Review 767 (2000).
Imwinkelried, The Debate in the DNA Cases Over
the Foundation for the Admission of Scientific Evidence: The Importance of Human
Error as a Cause of Forensic Misanalysis, 69 Washington University Law
Quarterly 19 (1991).
ABOUT THE AUTHORS
Edward J. Imwinkelried
University of California, Davis
Davis, CA 95616
Edward J. Imwinkelried is Distinguished Professor of Law and Director of Trial
Advocacy, University of California, Davis. He is the coauthor of Scientific
Evidence (3d Ed. 1999) and the Author of The Methods of Attacking Scientific
Evidence (3d ed. 1997). He is the expert testimony columnist for National Law
Journal and a forensic science columnist for Criminal Law Bulletin.
S1 Saddle River Road
Woodcliff Lake, NJ 07677
Michael Cherry, is a principal at GMC7 Inc. and a technologist who assisted NASA
in the development of celestial navigation imaging displays used by the Apollo
Moon Flight Simulator. He is a voting member of the evidentiary committee of
The Association for Information and Image Management (AIIM). He has appeared on
CNN Money Line. He is a Giga Expert who has published articles for the US
National Institute of Standards and Technology (NIST).
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To discuss specific questions raised in this article, log on to the CLPEX.com
board : (http://www.clpex.com/phpBB/viewforum.php?f=2)
Some of the questions might include:
1) Why do proficiency tests show a high error rate? (Addressed in The Detail
#54, and the Daubert Card)
2) Are you familiar with Judge Pollak’s decision to exclude fingerprint evidence
in the Llera-Plaza trial? Are you familiar with his reversal of that decision?
3) Do you use the ACE-V process to identify prints? Why do you feel ACE-V is a
reliable and valid process?
4) Are you familiar with California v. Mason case where two latent prints were
combined to be run in AFIS? (JFI Vol. No.) Do you feel this was a valid
5) Do you have the original image in this case? If not, where is it? Is it a
duplicate? Is it an accurate reproduction of the original evidence? How do you
know? (A best evidence rule may be invoked if the image is not an “original”
under FR 1001(3), or a “duplicate” under FR 1001(4))
6) Was the image you compared in this case the original impression found at the
crime scene? If not, how did you generate (enhance) the image that was compared?
7) If generated electronically, what software program was used? (could open up a
Daubert challenge to the accuracy of the particular software (or filter) used to
enhance the image)
8) Has that software program been appropriately validated? (under a Daubert
challenge, the prosecution must establish that “appropriate validation” has
occurred for that software program or filter that enhanced the image)
9) What guidelines did you follow in generating (enhancing) the image?
10) Is your testimony the product of reliable principles and methods? (under
Federal Rule of Evidence 702, this must be demonstrated)
11) Did you apply the principles and methods reliably to the image in this case?
(under Federal Rule of Evidence 702, this must be demonstrated)
12) Have you heard of AIIM? Are you aware of the AIIM guidelines at www.aiim.org?
Do you adhere to these guidelines? If not, why? Do you know about this
organization? Who is the President of AIIM?
13) Did you manipulate, create, or manufacture evidence in this case? Is your
image different than the original evidence?
So now you can imagine that no two
fingererprints are the same. It is a little bit like a living-room, in all the
world there will be no two the same living-rooms. Flowers, paintings, pictures,
trash, furniture and music will make every living-room unique!
Submitted by Michele Triplett
Copied on 4-21-03 from