Tracking down dozens — maybe hundreds — of other potentially innocent victims of junk science won’t be nearly as easy. There is no central repository of cases in which bite-mark testimony was key. There’s no database of dentists who testified about bite marks. And the cases are mostly decades old, and experts, defense lawyers and prosecutors have moved on or died. As Chaney settles into life on the outside after just a couple weeks of freedom — learning to use a cellphone and the TV remote — lawyers and criminal justice officials statewide are trying to figure out how to find others like Chaney. The Texas Forensic Science Commission, a tiny agency charged with overseeing the use of science in courtrooms, is working to ferret out those cases while ensuring that wrongful convictions based on faulty bite-mark interpretations don’t continue.
But it’s a lofty task, and the commission, with four employees and a $500,000 annual budget, can’t do it without help.
“We rely on the community’s willingness to step forward and take an introspective look at their work,” said Lynn Robitaille Garcia, the Forensic Science Commission’s executive director.
Since the 1950s, prosecutors have invoked the testimony of dentists who compared molds of suspects’ teeth to bite marks left at a crime scene.
In Chaney’s case, Dr. Jim Hales told the jury that there was a “one-to-a-million chance” that anybody but the Dallas construction worker had made a bite mark found on the body of one of the victims, John Sweek. (Chaney hasn’t been fully exonerated, and his case isn’t finally settled.)
In recent years, though, the nation’s foremost forensic science bodies have concluded that no scientific data exists to support the notion that such an exact match can be made.
In 2009, the National Academy of Sciences published a report that concluded there was insufficient scientific basis to conclusively match bite marks.
The Associated Press reported in 2013 that at least 24 people had been exonerated in cases in which bite-mark evidence played a central role in the conviction.
And even the American Board of Forensic Odontologists, the body that certifies dentists who analyze bite marks, has decided the evidence can’t be used to draw strong conclusions, such as in Chaney’s trial.
“People had made statements about the validity of bite marks that were greatly exaggerated,” said Dr. Adam Freeman, a forensic odontologist and the incoming American Board of Forensic Odontologists president.
Hales, in an affidavit filed with the court, acknowledged that the testimony he gave in Chaney’s case is inaccurate.
Chaney’s case is likely to be just the first of many reviewed.
In a set of bizarre Waco cases, at least three men were convicted of murder in trials that hinged on testimony from the same dentists involved in Chaney’s case. Two of the men were exonerated by DNA after spending a total of nearly two decades in prison.
The third man, David Spence, was sentenced to death and executed in 1997. His son, Jason Spence, wants prosecutors and the commission to reopen the case.
“I want his name cleared,” said Spence, who lives in Alabama. “They took away my father over something he did not do.”
To find more bite-mark cases, the Texas Forensic Science Commission will comb through legal documents available online. They’ll also ask prosecutors and defense lawyers to review old cases.
Dallas County District Attorney Susan Hawk is the first prosecutor in the nation to agree to an inmate’s release from prison because of faulty dental testimony. Other counties have taken note of the Chaney case, and some are reviewing old cases and mulling whether to continue using bite-mark evidence in prosecutions.
In Tarrant County, prosecutors are working with the medical examiner to determine how many involved bite marks. “We aren’t expecting it to be a large number,” said Samantha K. Jordan, a spokeswoman for District Attorney Sharen Wilson.
In Harris County, prosecutors will no longer go forward with cases in which a bite mark is the lone evidence.
Using bite evidence
The Forensic Science Commission has experience with searches for cases involving outdated science. But in many of those instances the forensic work in question was done in labs that track cases in a database.
Bite-mark cases are harder to identify, Robitaille Garcia said, partly because the work was usually conducted by individual dentists in their offices. No central bank of records in those cases exists. She hopes that the forensic odontologists board, which certifies some, but not all, such doctors, can also help.
Freeman, however, said his organization wants to help, but it did not track cases in which dentists testified.
“It’s terrifying to me that somebody could be convicted wrongfully,” Freeman said. “I would love to have a great solution, and I don’t.”
As if the task of identifying potentially innocent inmates wasn’t daunting enough, the commission must also weigh in on whether dental analysis should be used in a more limited scope or rejected altogether.
Freeman and the forensic odontologists board argue that bite-mark evidence should be used for limited purposes. It should only be used, he said, in cases where the suspects are known and the bite mark is identifiable.
“I wouldn’t say we should throw it away,” he said. “It should be put in the proper context.”
Lisa Tanner, an assistant attorney general who prosecutes violent cases statewide, said bite marks shouldn’t be relied on as the sole evidence in any case. But she and some other local prosecutors said that in certain instances the analysis can be useful.
In 2010, she prosecuted Blaine Milam in the death of his girlfriend’s 13-month-old daughter. The child had been beaten so catastrophically that the medical examiner could not determine which of the injuries killed her. In what was described as an effort to exorcise demons from the baby, Milam and the child’s mother left more than 20 bite marks on her tiny body.
“It was the worst thing I’ve ever seen,” Tanner said.
Evidence in the case, including DNA analysis, pointed to Milam and the baby’s mother, Jesseca Bain Carson. The bite-mark evidence, Tanner said, helped the jury understand what role each played in the murder.
A bite-mark analyst took molds of Milam’s teeth and of Carson’s teeth. His were jagged. Hers were straight. The dentist showed the jury photos of bruises on the baby’s elbows, knees, shoulder and neck. More of the bite marks, the dentist said, aligned with Milam’s jagged teeth.
“What the hell kind of human does that?” Tanner said. The jury decided Milam was the kind of human who deserved the death penalty. The baby’s mother was sentenced to life without parole.
Milam’s lawyer, Thomas Smith, did not return phone calls seeking comment.
Chaney said he hopes his case will serve as a warning to other prosecutors. He said the evidence shouldn’t be used under any circumstances.
“It’s not like fingerprints or DNA,” Chaney said. “What you are getting is somebody’s opinion, and it’s not fact.”
Chris Fabricant, director of strategic litigation at the New York-based Innocence Project, pointed to a study the forensic odontologists board conducted last year that concluded many of the dentists in the group couldn’t even identify which injuries were bite marks.
“There is no basic or applied research that supports any claims that bite-mark experts routinely make,” Fabricant said. “It has no business in criminal court, period.”