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Yet another innocence frontier

Scent lineups.

The Innocence Project of Texas said Friday that scent identification lineups, in which trained dogs determine if a suspect’s smell matches the smell of crime scene evidence, are based on faulty science and have led to a number of wrongful convictions.

The group, which tries to free the wrongly convicted, said it will release a report next week detailing at least five cases in which innocent people were arrested following scent ID lineups conducted by a Fort Bend sheriff’s deputy who trains dogs. Two of the five were jailed for capital murder before the charges against them were dropped.

Deputy Keith Pikett has spent about 20 years training dogs named Clue, James Bond and Columbo to sniff out possible criminals in more than 2,000 scent identification lineups. But the lineups have come under attack from some in the legal community, and Pikett is being sued by two people who claim they were wrongly implicated in crimes because of Pikett’s scent lineups.


Texas and Florida are the only states that regularly use scent identifications, [Jeff Blackburn, chief counsel for the Innocence Project of Texas,] said. The Innocence Project of Florida is reviewing about 20 cases involving a now dead dog handler who worked on three cases that later resulted in exonerations. Florida has since begun to restrict the use of scent lineups.

During a scent lineup, an officer wipes individual pieces of gauze or cloth on a suspect and several other people, and then places them in separate coffee cans, according to the lawsuits against Pikett. A trained dog is presented a piece of crime scene evidence, and is then led by Pikett to each can for a whiff. The dog is supposed to signal Pikett if it sniffs a match.


The lawsuits aren’t the first time someone took action against Pikett. In 2008, a now former Harris County assistant prosecutor e-mailed his colleagues to warn them about the “unreliable evidence” that came from Pikett’s work with Houston police, according to an affidavit.

Dr. Alejandro del Carmen, the chairman of the University of Texas at Arlington’s criminology and criminal justice department, compared scent identification to primitive criminology theories that identified suspects by body type. The once-accepted theory was that skinny people were too shy and heavy people too lazy to commit crimes.

“As a trained criminologist and a Ph.D., I find it nerve-racking that the justice system would rely on the ability of a dog to predict someone’s guilt or innocence,” del Carmen said.

Go read about Clever Hans if you’re unfamiliar with the potential pitfalls of relying on animals in this fashion. Grits, who has been following this for awhile, has more. The fact that only Texas is doing this should raise red flags about this practice. Maybe when dogs can be called to the stand to be cross-examined it’ll be different, but until then I think they ought to stick to search-and-rescue and tracking fugitives.

UPDATE: More from Grits.

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  1. […] Chron had a good story yesterday about “scent lineups” and the problems they’ve caused in criminal cases. Since one of the main arguments raised by […]

  2. […] can read that report here (PDF). I’ve blogged about this before here and here, and of course Grits is a comprehensive resource. It occurs to me that this is the sort of […]