News » San Antonio News

Texas Forensic Science Commission Asks For AG Opinion on Bite-Mark Evidence


A state commission is asking Texas Attorney General Ken Paxton to weigh in on their finding that bite-mark testimony used to convict people of crimes constitutes junk science.

The Texas Forensic Science Commission in February recommended a moratorium on the use of the controversial method. That's because a six-month study of forensic dentists who were asked to analyze photographs of 100 injuries showed that the dentists couldn't even tell which injuries were bite marks, according to the Innocence Project.

The commission, which is a watchdog over forensic testimony and analyses in Texas, calls the method negligent. But there are two authorities governing expert testimony in the Lone Star State and the Texas Forensic Science Commission wants Paxton to decide which one supersedes the other. The commission itself, which was created by the Legislature in 2005, won't accredit bite-mark analysts for trial testimony because it believes the practice is unreliable. However, the Texas Rules of Evidence allow experts to testify as long as they are "qualified by knowledge, skill, experience, training or education if scientific, technical or other specialized knowledge will assist the trier of fact," which currently legally covers forensic dentists who testify at trials. 

The commission is also looking for clarification of the legal requirements forensic labs have in reporting negligent practices. In Texas, there are forensic crime laboratories that practice in accredited forensic sciences, like DNA analyses, and in unaccredited analyses, like bite-mark practitioners. According to the Texas Forensic Science Commission, the labs, which are required to report negligence, don't consider it a legal obligation to report bite-mark negligence to the commission because the method isn't accredited. That's because there's not a single entity that exists in Texas to accredit practitioners and the commission won't do it because they believe it's unreliable, according to the AG opinion request. 

For instance, in 1987, police in Dallas were investigating the murder of John and Sally Sweek. The couple was murdered in their apartment where John sold cocaine. A man named Steven Mack Chaney was a customer who bought coke from the couple, but he also owed them a $500 debt. Investigators initially believed the Sweek's drug supplier killed the couple, but when an informant told authorities that Chaney was responsible, police ran with with the tip. In 1989, a jury convicted Chaney and sentenced him to life in prison.

According to the Innocence Project, the key testimony used to send Chaney to the pen for life came from two forensic dentists, James Hales and Homer Campbell, who said an injury on John's forearm was a bite mark and that there was a "[o]ne to a million" chance someone who wasn't Chaney could have left that bite mark. Despite nine witnesses who testified to alibis for Chaney, he was still convicted and sentenced to life.

Fast forward to 2015 and Chaney had already spent a quarter of a century behind bars. But in October of that year, a judge reversed the conviction based on discredited bite-mark analysis. Chaney was released from prison. His, however, is not the only case. According to the Innocence Project, bite-mark testimony has resulted in 24 wrongful convictions or indictments.

However, the Texas Forensic Science Commission's moratorium on bite-mark testimony isn't legally binding, according to the Washington Post's Radley Balko, who says flawed convictions obtained through bite-mark testimony could be in the hundreds. Lynn Garcia, general legal counsel for the Texas Forensic Science Commission, wrote in the request that Paxton's opinion will help the body provide better guidance to the forensic community. Garcia did not return a request for comment.

Support Local Journalism.
Join the San Antonio Current Press Club

Local journalism is information. Information is power. And we believe everyone deserves access to accurate independent coverage of their community and state. Our readers helped us continue this coverage in 2020, and we are so grateful for the support.

Help us keep this coverage going in 2021. Whether it's a one-time acknowledgement of this article or an ongoing membership pledge, your support goes to local-based reporting from our small but mighty team.

Join the San Antonio Press Club for as little as $5 a month.