AUSTIN, Texas - Two Texas death row inmates are pushing for the state to ban forensic hypnosis in criminal cases.

Hypnosis played a critical part in the arrest and conviction of Charles Don Flores, 48, and Kosoul Chanthakoummane, 37, the Dallas Morning News reported . Both men allege their convictions were based on "junk science" and their executions have been delayed.

Flores was convicted in the 1998 killing of Elizabeth "Betty" Black. A neighbour was hypnotized to help her remember the features of two men she witnessed entering the victim's home the morning of the slaying.

Chanthakoummane was convicted in 2007 in the stabbing death of real estate agent Sarah Walker. A hypnotized witness helped the police identify Chanthakoummane through a sketch.

Texas has a robust forensic hypnosis program, where police officers are trained statewide to sharpen or recall witnesses' lost memories. The Texas Rangers have conducted two dozen hypnosis sessions over the past two years.

Half of all U.S. states have banned using memories retrieved from hypnosis as evidence in criminal cases, according to a 2012 study.

"Hypnosis is utilized in a very small percentage of cases and is conducted only by specially trained forensic hypnotists," said Tom Vinger, Texas Department of Public Safety spokesman. "Any information gained through hypnosis must be corroborated with other information/evidence during the course of a criminal investigation."

Some experts caution that hypnosis can alter memories or create false ones.

"It's pretty easy to have people change or modify memories, at least to some extent, by the use of hypnosis," said Joseph Green, a professor at Ohio State University at Lima. He said that memory techniques like hypnosis are "fraught with pitfalls and danger, leading questions and bias from the interviewer."

Some of the state's rules outlining best practices for forensic hypnosis weren't followed in Flores' case. For example, the hypnosis session wasn't taped from the first interaction with the witness. Also, an officer working on the investigation helped conduct the hypnosis, which is typically prohibited.

"Are there some cases out there where a police officer did a bad job on hypnosis? Yes," said Marx Howell, who helped design the Texas' forensic hypnosis program. "But Texas has the most well-organized, comprehensive program in the United States."

Flores is waiting for a judge to decide whether he'll be granted a new trial after the Texas Court of Criminal Appeals blocked his execution in 2016.

Chanthakoummane has a hearing set for July in McKinney. Last June, the appeals court sent his case back to trial court in Collin County to review whether scientifically invalid testimony was used to convict him.

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Information from: The Dallas Morning News, http://www.dallasnews.com

News from © The Associated Press, 2018