To Err Is Human


permanent, can result in other problems for the AFIS machine as it tries to compare fingerprints. In addition, electronic sensing adds "noise" that can distort fingerprint images. Anyone who has scanned images and then tried to print them or project them through a multimedia projector has experienced this phenomenon to one degree or another.

Interestingly the AFIS was developed to use the same processes that the fingerprint examiner uses in manually comparing fingerprints, but


FBI examiners subsequently verified the identification. The court also appointed an independent examiner, not employed by the FBI, to examine the fingerprint, and he agreed that the fingerprint belonged to Mayfield. It should be pointed out that the database includes not only criminals but also anyone who has ever served in the military or worked in law enforcement or a security position. In this case public records show that Mayfield was arrested for burglary in Wichita, Kansas, on December 22, 1984, in addition to having served in the army.

Prior to the AFIS "hit," law-enforcement officers had no reason to believe Mayfield had any involvement in the bombings. The investigation commenced solely on the basis of the fingerprint. By mid-April 2004 Spanish officials were questioning whether the print was Mayfield's. In response the FBI sent a team of fingerprint examiners to Madrid to view the evidence directly only to learn it had been destroyed.

According to a motion filed in the U.S. district court in Oregon, Spanish officials ultimately linked the latent print to a different individual and the FBI began a reexamination. Two FBI latent print examiners flew to Spain to examine the best possible digital image maintained by Spanish officials. Four additional FBI examiners back in Quantico, Virginia, then joined the effort. On May 24, 2004, the FBI withdrew its previous fingerprint identification.

i the machine cannot compensate for complex visual textures, sweat pores, or ridge thickness, all of which can be factored in by the human examiner. Without the benefit of the "art" the human examiner has developed over years of training and experience, AFIS evaluation is incomplete.

The public tends to put more faith in computers than in people because, as everyone knows, humans make mistakes. There is a notion that AFIS is foolproof, but it is not. After all, humans made computers, and a human must make the ultimate decision as to fingerprint identification or nonidentification. So, errors can and sometimes do happen. High-profile cases, by their very nature, draw lots of interest and publicity, and when an error has been made on a fingerprint case, it tends to distort the perceived accuracy of the field. In fact, the error rate for fingerprint identification, whether assisted by AFIS or not, has been very low through the years.

The goal of forensic evidence is the identification of the perpetrator of a crime. Firearms and fingerprint evidence both offer the opportunity for positive identification. Firearms identification is limited to identifying the responsible firearm or ammunition component, while fingerprint identification is capable of identifying the responsible individual. The combination of firearms and fingerprint evidence offers insight into both who committed a crime and how that crime may have been committed.

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