DNA evidence tied Chanthakoummane to Sarah Walker’s murder at a model home in Collin County.
TEXAS, USA — Texas plans to execute Kosoul Chanthakoummane on Wednesday for the 2006 murder of a real estate agent in a Collin County model home. It would be the second execution this year in a state that typically puts more people to death than any other.
Chanthakoummane, now 41, is set to die for the murder of Sarah Walker, who was brutally beaten and stabbed to death while showing a home in a McKinney subdivision. The 40-year-old’s Rolex watch and ring were missing when police arrived.
Witnesses placed Chanthakoummane at the model home, and a bite mark on Walker’s back and blood under her fingernails and at the scene were linked to him, according to court records. The death row prisoner has long claimed he is innocent.
Over his nearly 15 years on death row, the prisoner’s attorneys have chipped away at the reliability of evidence against him. Forensic scientists have largely debunked the ability to match bite marks to an individual. And the witnesses who testified Chanthakoummane was the man they saw on the day of the murder had previously been hypnotized by police investigators, despite scientific evidence that the practice can distort memories.
But analysts also determined his DNA was on Walker’s fingernails and elsewhere at the crime scene, and that evidence largely has convinced the courts they have the right man. In his last appeals to Collin County and the Texas Court of Criminal Appeals filed last week, Chanthakoummane’s attorneys argued that the DNA evidence is also questionable.
Under a 2013 Texas “junk science” law, courts can overturn a conviction when the scientific evidence presented at trial has since changed or been discredited.
“Critically, current scientific knowledge contradicts the trial court’s previous finding that the ‘only reasonable inference’ to be drawn from the DNA evidence is that Mr. Chanthakoummane violently attacked Ms. Walker,” wrote attorneys Catherine Clare Bernhard and Eric J. Allen.
In a court filing, the Collin County district attorney’s office replied that “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.”
After Walker was killed, police initially looked at people close to her. Friends pointed to her ex-husband or romantic partners, and others reported foreign investors were upset with her for big losses in real estate deals, according to Chanthakoummane’s latest filing. Walker was also robbed and attacked at her home several months earlier, while Chanthakoummane was incarcerated in North Carolina for an armed robbery committed when he was 16.
DNA from blood samples and another real estate agent’s report shifted the investigation’s focus to Chanthakoummane. The other agent, who was selling a home near Walker’s model home, and her husband told police they saw an Asian man in a white Ford Mustang park across the street from the model home around the time of the murder. The couple later agreed to hypnosis by a Texas Ranger to see if they could remember more, but the state said the controversial practice did not significantly alter their testimony.
At trial, another real estate agent testified that the day before Walker’s murder, Chanthakoummane came to her home and asked to use the phone, saying his car broke down, according to court documents. She called the police when he refused to leave.
Chanthakoummane originally denied ever going to the model home, but under police interrogation said he went into the home to use the phone and drink some water after having car trouble. He said he didn’t see anyone inside and noted previous injuries on his hands could have left blood behind.
Police and prosecutors rejected the statement, but Chanthakoummane’s lawyers say new scientific research shows his DNA could have been transferred to Walker’s fingernails without any direct contact between them — for instance, if she touched an object he had left a blood mark on. The National Institute of Standards and Technology issued a draft report last year that said the possibility of such transfers can’t be ignored in criminal investigations.
Chanthakoummane’s lawyers noted an example of a man who was suspected of murder because his DNA was found on the fingernails of a homicide victim. It was later discovered the suspect had been injured on the day of the killing and ridden in the same ambulance as the homicide victim hours earlier, resulting in his DNA transfer.
Collin County Assistant Criminal District Attorney Lisa Braxton said the concept of DNA transfers, however, is not new.
“Contamination and transfer are and always have been a consideration in the interpretation of mixtures,” the prosecutor wrote in her filing. “And even if the review’s conclusions constituted ‘new’ science, Chanthakoummane presents no evidence that the lab misinterpreted the DNA mixture on the victim’s fingernails – or any other mixture, for that matter.”
Chanthakoummane’s last appeal also attempts to discredit witness testimony stating his car was outside the model home around the time of Walker’s murder. His lawyers stated that a former deputy chief of the Richardson Police Department told homicide investigators he spoke to Walker in the model home for several minutes around the time she is believed to have been killed. The deputy chief mentioned another car with a woman driving on the street, but not a white Mustang.
The prisoner’s attorneys also noted new DNA testing done last year on samples from a plant stand, thought by prosecutors to have been used to fatally beat Walker, did not match Chanthakoummane and instead possibly implicated another person.
“Unsurprisingly, the defense did not highlight the gaps and inconsistencies in the State’s theory, including the inconsistent accounts regarding when the white Mustang was observed near the crime scene,” Bernhard and Allen wrote.
In 2019, Chanthakoummane had argued for a new trial because his lawyer told jurors he was guilty against his wishes. The prisoner told the courts he insisted on maintaining his innocence, but instead, his lawyer said in his opening statement that Chanthakoummane wanted to rob Walker and ended up killing her.
The Court of Criminal Appeals rejected the prisoner’s pleas for a new trial, saying he could have raised the issue earlier, despite the U.S. Supreme Court ruling in 2018 that the Sixth Amendment guarantees a defendant the right to insist that his counsel refrain from admitting guilt.
Without court intervention Wednesday, Chanthakoummane will be injected with a lethal dose of pentobarbital in the state’s death chamber in Huntsville after 6 p.m.
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