Few law enforcement institutions have been so thoroughly discredited in recent years as the FBI's forensic laboratory. In 1997, the Bureau's inspector general (IG) at the time issued a devastating report, stigmatizing one instance after another of mishandled and contaminated evidence, inept technicians, and outright fabrication. The IG concluded that there were "serious and credible allegations of incompetence" and perjured courtroom testimony.

My view is that taken as a whole, forensic evidence as used by prosecutors is inherently untrustworthy. Of course the apex forensic hero of prosecutors, long promoted as the bottom line in reliability -- at least until the arrival of DNA matching -- has been the fingerprint.

Fingerprints entered the arsenal of police and prosecutors in the late 19th century, touted as "scientific" in the manner of other fashionable methods of that time in the identification of supposed criminals, such as phrenology. Decade after decade people have been sent to prison for years or dispatched to the death cell, solely on the basis of a single, or even a partial print. In the United States, part of the mystique stems from the "one discrepancy rule," which has supposedly governed the FBI's fingerprint analysis. The rule says that identifications are subject to a standard of "100 percent certainty," where a single difference in appearance is supposed to preclude identification.

The 1997 lab scandals threw a shadow over the FBI's forensic procedures as a whole, and the criminal defense bar began to raise protests against prosecutorial use of latent fingerprint identification evidence, as produced by FBI procedures.

Now, at last, in 2006, the FBI's current inspector general, Glenn Fine, has grudgingly administered what should properly be regarded as the deathblow to fingerprint evidence as used by the FBI and indeed by law enforcement generally.

The case reviewed by Inspector General Fine, at the request of U.S. Rep. John Conyers and U.S. Sen. Russell Feingold, concerns the false arrest by the FBI of Brandon Mayfield, a lawyer from Beaverton, Ore.

On March 11, 2004, several bombs exploded in Madrid's subway system with 191 killed and more than 2,000 injured. Shortly thereafter, the Spanish police discovered a blue plastic bag filled with detonators in a van parked near the Alcala de Heneres train station in Madrid, whence all of the trains involved in the bombing had originated on the fatal day.

The Spanish police were able to lift a number of latent prints off the bag. On March 17, they transmitted digital images of these fingerprints to the FBI's crime lab in Virginia. The lab ran the images through its prized IAFIS, otherwise known as the integrated, automated, fingerprint identification system, containing a database of some 20 million fingerprints.

The IAFIS computer spat out 20 "candidate prints," with the warning that these 20 candidates were "close non-match." Then the FBI examiners went to work with their magnifying glasses, assessing ridges and forks between the sample of 20 and the images from Spain. In a trice the doubts of the IAFIS computer were thrust aside, and senior fingerprint examiner Terry Green determined that he had found "a 100 percent match" with one of the Spanish prints of the fourth-ranked print in the IAFIS batch of 20 close non-matches. Green said this fourth-ranked print came from the left index finger of Brandon Mayfield. Mayfield's prints were in the FBI's master file, not because he had been arrested or charged with any crime, but because he was a former U.S. Army lieutenant.

The FBI lost no time in alerting the U.S. Prosecutor's office in Portland. Surreptitious tapping and surveillance of Mayfield began. On April 2, 2004, the FBI sent a letter to the Spanish police informing them that they had a big break in the case, with a positive identification of the print on the bag of detonators.

Ten days later, the forensic science division of the Spanish national police sent the FBI its own analysis. It held that the purported match of Mayfield's print was "conclusively negative."

On April 14, the U.S. prosecutor in Portland became aware of the fact that the Spanish authorities were vigorously disputing the match with Mayfield's left forefinger. But by now the prosecutor and his team were scenting blood. Through covert surveillance they had learned that Mayfield was married to an Egyptian woman, had recently converted to Islam, was a regular attendee at the Bilal mosque in Portland, and had as one of his clients in a child custody dispute an American Muslim called Jeffrey Battle. Battle, a black man, had just been convicted of trying to go to Afghanistan to fight for the Taliban.

Mayfield had no idea that the FBI had been tapping his phones and secretly rummaging through his office. The first time he became aware that he was a citizen under suspicion was on the afternoon of May 6. On that day, eight FBI agents showed up at his law office, seized him, cuffed his hands behind his back, and ridiculed his protestations.

Mayfield ended up with two federal public defenders, Steven Wax and Christopher Schatz. Like many such, these two were dedicated to the interest of their client, tireless and resourceful.

The two public defenders went before Judge Jones and asked that as a material witness he be kept under house arrest, there being scant apparent evidence against him. Judge Jones finally compelled the U.S. Prosecutor to say what evidence he had against Mayfield. A fingerprint, said the U.S. Prosecutor, withholding from the court the fact that this fingerprint was highly controversial and had been explicitly disqualified by the Spanish police.

The federal defenders questioned the imprisonment of their client, faced penalties of the utmost gravity, on the basis of a fingerprint. Judge Jones allowed as how he had sent people to prison for life on the basis of a single fingerprint. Mayfield's attorneys asked to see a copy of the allegedly matched fingerprints and have them evaluated by their own expert witness. Knowing he was on thin ice the U.S. Prosecutor refused, claiming it was an issue of national security. Under pressure from Judge Jones, himself pressured by the assiduous federal defenders, the U.S. Prosecutor finally agreed he would give the prints to an independent evaluator selected by Judge Jones.

The prints were given to Kenneth R. Moses of San Francisco, an SFPD veteran who runs a company called Forensic Identification Services, which, among other things, proclaims its skills in "computer enhancement of fingerprints." It was "quite difficult," Moses said, because of "blurring and some blotting out," but yes, the FBI had it right, and there was "100 percent certainty" that one of the prints on the blue bag in Madrid derived from the left index finger of Brandon Mayfield.

Moses transmitted this confident opinion by phone to Judge Jones on the morning of May 19. Immediately following Moses' assertion, the U.S. attorney stepped forward to confide to Judge Jones dismaying news from Madrid from the Spanish police that very morning. The news "cast some doubt on the identification." This information, he added, "was classified or potentially classified."

The prosecutors then huddled with the judge in his chambers. After 20 minutes, Judge Jones stormed back out and announced that the prosecutors needed to tell the defense lawyers what they had just told him. The prosecutor duly informed the courtroom that the Spanish police had identified the fingerprint as belonging to the right middle finger of Ouhnane Daoud, an Algerian national living in Spain. Daoud was under arrest as a suspect in the bombing. Judge Jones ordered Mayfield to be freed.

Five days later, on May 24, the warrant for his detention was dismissed.

The FBI sent two of their senior fingerprint analysts to Spain on a mission to salvage the Bureau from humiliation. The two analysts did their best, returning with the claim that the fingerprint sent to the FBI by the Spanish police was of "no value for identification purposes," a claim that the Inspector General later shot down by pointing that only a few weeks thereafter, the FBI's latent fingerprint unit concurred with the Spanish national police lab's determination that the print on the bag matched the right middle finger of Ouhnane Daoud.

The inspector general writes the bottom line on the "science" of fingerprint matching. He gets the FBI's top examiner to admit that if Mayfield had "been like the Maytag repair man" and not a Muslim convert married to an Egyptian, "the laboratory might have revisited the identification with more skepticism."

And Daoud's fingerprint match? I don't know, but if he were convicted on the basis of fingerprints alone, I would say there are grounds for an appeal.

Alexander Cockburn is coeditor with Jeffrey St. Clair of the muckraking newsletter CounterPunch. He is also co-author of the new book "Dime's Worth of Difference: Beyond the Lesser of Two Evils," available through www.counterpunch.com. To find out more about Alexander Cockburn and read features by other columnists and cartoonists, visit the Creators Syndicate Web page at www.creators.com. COPYRIGHT 2006 CREATORS SYNDICATE, INC.