Bite analysis cited in effort to free man in Dallas killings

DALLAS— For a man who has been in prison for more than 25 years for the 1987 stabbing deaths of two people in Dallas are asking a judge to set him free, saying testimony analyzing bite marks on one of the victims is invalid.

The Dallas Morning News reports that in an affidavit filed Friday, dentist Jim Hales says he was wrong when he told a Dallas County jury in 1989 that there was a “1 to a million” chance that someone other than Steven Mark Chaney made the bite marks found on John Sweek’s body.

Lawyers for Chaney, a 59-yearold former construction worker, argue he is innocent. They are asking the judge for Chaney’s freedom based on the new evidence that the bite analysis was invalid and on allegations of prosecutor misconduct, including withholding evidence and eliciting false testimony.

A hearing in the case is set for Monday. The Dallas County district attorney’s office did not immediately return a call from The Associated Press for comment Sunday.

Lawyer Julie Lesser of the Dallas County public defender’s office wrote in a court document seeking Chaney’s acquittal and release from prison that “new evidence has gutted the case against him.” Chaney is serving a life sentence in the deaths of John and Sally Sweek.

During Chaney’s trial, prosecutors said he killed John Sweek to avoid paying a debt to the drug dealer. The prosecutors hired two forensic dentists who said they spent hours matching the bite marks on John Sweek’s arm to molds of Chaney’s teeth.

But in the affidavit filed Friday, Hales said the information he provided to jurors has since been invalidated.

“Conclusions that a particular individual is the biter and their dentition is a match when you are dealing with an open population are now understood to be scientifically unsound,” Hales said.

During the trial, Chaney’s lawyers presented nine witnesses who said they had spent time with Chaney the day of the slayings and that he couldn’t have been at the Sweeks’ home when they were killed.

At least one juror said after the trial that the bite evidence convinced her that he was guilty.

In recent years, forensic scientists have raised doubts about the reliability of bite mark evidence. In 2009, the National Academy of Sciences published a report that concluded there was insufficient scientific basis to conclusively match bite marks. The Texas Forensic Science Commission is reviewing cases in which bite analysis contributed to a conviction to determine whether those cases warrant further investigation.

Texas lawmakers passed legislation in 2013 that allows courts to grant inmates relief from their convictions if advancements in science undermine the evidence used in their cases. Chaney’s lawyers argue that he should be acquitted under that statute and freed.

The defense lawyers also argue that prosecutors knowingly presented false evidence that blood had been found on the bottom of Chaney’s tennis shoe. They say prosecutors withheld notes from another expert who said there was no blood on Chaney’s shoes.

They also say prosecutors elicited false testimony from a co-worker of Chaney’s, who initially told police that Chaney had asked him to be a “witness” to tell authorities that he had last been at the victims’ home a week before the killings. But at trial, the co-worker told the jury that Chaney had asked him to be an “alibi” witness.