Texas Executes Man Whose Conviction Relied on Discredited Forensics

Texas on August 17, 2022 exe­cut­ed Kosoul Chanthakoummane (pic­tured), whose con­vic­tion pros­e­cu­tors obtained with dis­cred­it­ed foren­sic tes­ti­mo­ny. He was the sec­ond defen­dant of col­or in less than a month to be put to death over the objec­tion of the victim’s family.

Chanthakoummane was con­vict­ed and sen­tenced to death in Collin County for the 2006 mur­der of Sarah Walker, a real estate agent who was found mur­dered in a mod­el home. He has long main­tained his innocence. 

Chanthakoummane’s con­vic­tion relied on bite-mark analy­sis and wit­ness hyp­no­sis, two dis­cred­it­ed foren­sic tech­niques, and sta­tis­ti­cal­ly flawed DNA tes­ti­mo­ny. The son of Laotian refugees who escaped to the United States dur­ing the Vietnam war, Chanthakoummane admits that he stopped in the mod­el home because he was hav­ing car trou­ble. While there, he says, he got a glass of water from the sink, leav­ing behind his DNA. Prosecutors say his DNA was found under Walker’s fin­ger­nails and in var­i­ous loca­tions through­out the house.

Walker’s father, Joe Walker, said in a video, ​“I don’t have any hate towards him at all. I don’t want him put to death.”

When her body was dis­cov­ered, Sarah Walker had a bite mark on the back of her neck. Prosecutors retained foren­sic den­tistry con­sul­tant Brent Hutson to try to link Chanthakoummane to that bite. Hutson made a mold of the bite and, using Adobe Photoshop, com­pared it to a mold of Chanthakoummane’s teeth. At tri­al, Hutson tes­ti­fied that he was ​“unable to exclude [Chanthakoummane] from that pop­u­la­tion of indi­vid­u­als that could have inflict­ed this injury.”

Bite mark evi­dence is noto­ri­ous­ly unre­li­able and was been dis­cred­it­ed by the National Academies of Science, which, in its land­mark August 2009 report by its National Research Council, Strengthening Forensic Science in the United States: A Path Forward, found ​“no evi­dence of an exist­ing sci­en­tif­ic basis for iden­ti­fy­ing an indi­vid­ual to the exclu­sion of all oth­ers.” As of 2019, false bite mark tes­ti­mo­ny had been impli­cat­ed in 31 wrong­ful con­vic­tions. In 2016, the Texas Forensic Science Commission joined the National Academies in con­clud­ing that ​“there is no sci­en­tif­ic basis for stat­ing that a par­tic­u­lar pat­terned injury can be asso­ci­at­ed to an individual’s den­ti­tion,” and rec­om­mend­ed that bitemark tes­ti­mo­ny no longer be per­mit­ted in criminal cases.

Prosecutors also pre­sent­ed tes­ti­mo­ny from two wit­ness­es who tes­ti­fied that they had seen a ​“man of Asian descent” walk­ing toward the mod­el home on the day of Walker’s mur­der. However, Texas Ranger Richard Shing had hyp­no­tized the wit­ness­es, encour­ag­ing them to use their ​“mind’s eye” to imag­ine the sus­pect from dif­fer­ent angles. Hypnosis of wit­ness­es and sus­pects was wide­ly used by the Texas Rangers until 2021, when they sus­pend­ed its use because it can lead to false or misleading testimony.

In seek­ing the death penal­ty against Chanthakoummane, pros­e­cu­tors ignored the vocal objec­tions of the victim’s fam­i­ly. At Sarah Walker’s funer­al, her father asked those in atten­dance to pray for her mur­der­er. He also told pros­e­cu­tors that he did not want them to seek the death penal­ty. In a video, Joe Walker, who has since died, said, ​“I’d be fool­ish to say I wasn’t angry about [the mur­der]. But I’m not angry enough to reject the Lord and his teach­ings. … Our Lord said that the greater the sin­ner, the more enti­tled they are to mercy.” 

In 2017, the Texas Court of Criminal Appeals (TCCA) grant­ed Chanthakoummane a stay of exe­cu­tion and direct­ed the tri­al court to hold a hear­ing on his junk sci­ence claims. At that hear­ing, Chanthakoummane pre­sent­ed expert tes­ti­mo­ny that the hyp­not­i­cal­ly refreshed tes­ti­mo­ny against him was unre­li­able, that bite-mark iden­ti­fi­ca­tion tes­ti­mo­ny has no sci­en­tif­ic valid­i­ty, and that the pros­e­cu­tion tes­ti­mo­ny on DNA relied on erro­neous data in the FBI DNA data­base and flawed sta­tis­ti­cal method­ol­o­gy. The tri­al court reject­ed his claims, sign­ing the pro­posed factfind­ing sub­mit­ted by Collin County prosecutors verbatim.

In 2020, a bad­ly divid­ed TCCA vot­ed to uphold his con­vic­tion and death sen­tence. Four judges agreed that Chanthakoummane had shown that the pros­e­cu­tion had pre­sent­ed false DNA tes­ti­mo­ny, but found that prop­er DNA analy­sis would still have point­ed to him as hav­ing been present at the crime scene and the con­trib­u­tor of DNA found under the victim’s fin­ger­nails. The major­i­ty also agreed that the bite-mark tes­ti­mo­ny had been dis­cred­it­ed, but deemed its use harm­less in light of the remain­ing evi­dence against him. The court also reject­ed Chanthakoummane’s chal­lenge to the use of hyp­not­i­cal­ly-induced tes­ti­mo­ny on pro­ce­dur­al grounds, say­ing that the flawed nature of the prac­tice was already known and should have been raised at the time of tri­al. Three judges dis­sent­ed, say­ing the court should have agreed to review the con­sti­tu­tion­al­i­ty of the hypnosis evidence.

Chanthakoummane is one of six­teen defen­dants sen­tenced to death in Collin County, three-quar­ters of whom have been Asian (2), Black (3), or Latinx (7). Eight of those defen­dants have now been exe­cut­ed, six of whom were Black (2), Latinx (3), or Asian (1).

[UPDATED TO REFLECT THAT THE EXECUTION WENT FORWARD ON AUGUST 17, 2022.]