The Innocence Project of Texas has raised questions about using sniffer dogs to single out potential suspects.

But on March 16, 2006, Buchanek found himself sitting in the interrogation room. This time, he was on the other side of the table. The day before, his neighbor and friend, Sally Blackwell, was found strangled to death with a rope. Her body was left in a field five miles from her home.

Buchanek sat in the interrogation room with three homicide investigators, former brothers on the force. But the investigators were no longer friends. Buchanek was now the prime suspect in Blackwell's murder.

"They told me they knew I did it and that I was going to spend the rest of my life on death row," Buchanek told CNN.

The story of how a veteran law enforcement officer became a murder suspect is at the heart of a controversy over an investigative forensic tool called dog-scent lineups.

The Innocence Project of Texas calls the practice "junk science that's being used by prosecutors and judges to convict people." The nonprofit group, which is dedicated to discovering and overturning wrongful convictions, wants state governments to ban the use of dog-scent lineups. It says an unknown number of people have been wrongly accused or convicted from the dog-scent lineups.

Supporters say dog-scent lineups are a powerful crime-fighting tool helping investigators crack cases across the country.

Buchanek was identified as a murder suspect, not because of crime-scene evidence but because of two bloodhounds, "Jag" and "James Bond."

The dogs belong to Fort Bend County Sheriff's Deputy Keith Pikett. He and his team of dogs have become celebrities in Texas law enforcement circles for their work on hundreds of cases across the state.

In Buchanek's case, homicide detectives in this county southwest of Houston had Pikett's bloodhounds sniff crime-scene evidence, such as the rope used to strangle the victim. The dogs matched the scent to Buchanek. 

Despite repeated denials, Buchanek lived under a cloud of suspicion for five months. His former Sheriff's Office colleagues believed the dogs over him and his pleas of innocence. But the dogs were wrong.

DNA evidence implicated another man, who pleaded guilty to the murder.

"It's left me with a pretty bad taste for law enforcement," Buchanek said. "It's pretty much ruined my life altogether."

Buchanek has filed a civil rights lawsuit against Pikett, the dog handler in Fort Bend County, as well as the Victoria Sheriff's Office and the Victoria Police Department. Buchanek is seeking unspecified damages claiming his constitutional rights were violated when he was falsely accused and that he suffered mental anguish as a result.

Pikett and his dogs have assisted in hundreds of investigations for law enforcement agencies across Texas. Pikett refused CNN's interview requests, but his attorney says Pikett is on the "cutting edge" of collecting dog-scent forensic evidence.

Buchanek accuses the investigators, including Pikett, of "leading" the dogs to his home because Buchanek knew the murder victim through work and church.

Pikett's attorney denies this. "The dogs were pulling him (Pikett)," said Randall Morse, the assistant county attorney in Fort Bend County who is representing the dog handler. "Pikett did not lead the dogs. The trail was valid."

Morse said Pikett is a respected officer of the law who has helped developed protocols for dog-scent lineups over the last two decades. "He's been accused 20 different ways of cheating; critics are trying to throw up smoke to get defendants off," Morse said.

Victoria County Sheriff T. Micheal O'Connor said dog-scent lineups, like other investigative aids, are a "vital tool in working toward a determination of a case." He opposes banning the technique.

"We will use them again if it merits this type of service," he said. "I feel they're credible. I've watched those dogs. I looked on in absolute amazement."

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