September/October 2003, Page p36

The myth of fingerprints
By Edward J. Imwinkelried; Michael Cherry

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 science community was stunned when Judge Pollak excluded fingerprint testimony in United States v. Llera Plaza,2 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 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 fingeprint 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 1990s. However, it has become so widespread that CBS News recently aired a 6O 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 County 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?

The technology
Image enhancement. In some cases, that expression means image enhancement.6 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 contrast.
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 printing 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 Segundo, 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 the other — to create a thumbprint that could be run through a database. The El Segundo 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 Automated Fingerprint Information 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 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)?8

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 the 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 program.

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 Rule 1001(4).

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 prosecu

tion witnesses.
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 splatters, 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.

Notes
1. 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).
2. 179 F.Supp.2d 492 (E.D.Pa. 2002))
3. 188 F.Supp.2d 549 (E.D.Pa. 2002).
4. A written version of the segment is available on the Internet at http://uttm.com/stories/2002/11/19/60II/main530029.shtml.
5. Several departments use software developed by PC Professionals. PC Professionals posts its client list at http://pcprosusa.com/clients.html.
6. See generally 2 P. Giannelli & E. Immwinkelried, Scientific Evidence 25-6.1 (2002 Supp.).
7.G. Joseph, Modern Visual Evidence 8-22 (1999).
8. 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 toll free number is (800) 477-2446, its FAX number (301) 587-2711, and its E-mail address aiim@aiim.org.
9. 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).
10. Risinger, Defining the ‘Task at Hand’: Non-Science Forensic Science After Kumho Tire Co. v. Carmichael, 57 Washington & Lee Law Review 767 (2000).
11. 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).


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