A convicted murderer was executed at the Texas State Penitentiary in Huntsville more than 16 years after he committed the crime that got him sentenced to death.

Kosoul Chanthakoummane was found guilty of murdering real estate agent Sarah Walker in 2006, as reported by The Dallas Express. He stabbed her more than 30 times inside a model home in Collin County.

Walker was one of the top agents for her firm and the mother of two children.

Chanthakoummane was on parole from a prison stint in North Carolina for a prior aggravated kidnapping and robbery when he killed Walker. His DNA was found under her fingernails, and his bloody fingerprints were found on the scene.

Still, Chanthakoummane maintained his innocence and his current attorneys argued that new “scientific” developments indicated that their client’s DNA could have been transferred to the victim without any direct contact.

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However, during the original trial, Chanthakoummane’s attorney at the time told the jury that he “did go into a model home, and that’s where Sarah Walker was. And he wanted to rob her, and it didn’t go the right way, and he killed her.”

Some of the evidence supporting Chanthakoummane’s guilt has been called into question.

For example, a bite mark on Walker’s neck was said to have been matched to Chanthakoummane, but in recent years, the Texas Forensic Science Commission has raised serious concerns about the practice of such “identifications.”

Similarly, several of the witnesses who claimed they saw Chanthakoummane at the crime scene had been interrogated by forensic hypnotists to “sharpen or recall [their] lost memories.”

Still, the office of Collin County’s district attorney rejected claims that the conviction had been based on “junk science.”

The office argued to the court, “Chanthakoummane presents no new science in the field of DNA analysis, and even if there were something new, he fails to show it would have prevented his conviction.”

The average time spent on death row in Texas is a little over 11 years, according to the Texas Department of Criminal Justice. However, the state’s existing death row population has been awaiting execution for more than 17 years on average.

Before his execution by lethal injection, Chanthakoummane said, “To Mrs. Walker’s family, I pray that my death will bring them peace.”