Prosecutors, who told jurors at Chaney's 1987 trial that Chaney killed the Sweeks over a drug debt, based their case on an expert witness who testified there was only a one-in-a-million chance that a bite on John Sweek's arm came from anyone other than Chaney. In the years following Chaney's conviction and sentence to life in prison, scientific studied showed bite-mark evidence to be unreliable at best.
In its decision, the Texas Court of Criminal Appeals ruled that bite-mark evidence no longer being considered legitimate would've changed the outcome of Chaney's trial.
"Instead of supporting the conclusions that Chaney bit John at the time of the murders, the evidence would now show, at most, only that John might have been bitten two to three days before the murders and that if John was bitten by someone, that person could be Chaney (or anyone else on the planet whose dentition has not been excluded)," Judge Barbara Parker Hervey wrote in her decision.
“Today’s decision is groundbreaking, a huge step forward in the fight against the weaponized use of unreliable evidence passed off as science." – M. Chris Fabricant, the Innocence Project
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As Chaney sat in jail, attorneys from the Innocence Project and Dallas County's Conviction Integrity Unit took up his case, working to discredit the pseudo-scientific testimony used to convict him — Texas passed a law in 2013 allowing inmates to challenge conviction based on now-discredited science — and finding new suspects in the case by testing DNA found at the scene of the murders. None of the DNA at the crime scene matched Chaney.
In 2015, Chaney's conviction was overturned and he was released on bond. A year later, former Dallas County prosecutor Neil Pask testified at a Dallas County hearing that Chaney should be found actually innocent, rather than merely having his conviction overturned. Pask said that he'd been wrongly swayed by the bite-mark evidence in the case.
M. Chris Fabricant, director of strategic litigation for the Innocence Project, said Wednesday that Chaney's exoneration by the Texas Court of Criminal Appeals is a key step forward in the fight against junk science being used as evidence.
“Today’s decision is groundbreaking, a huge step forward in the fight against the weaponized use of unreliable evidence passed off as science in our courts,” Fabricant said. “We are encouraged that the law is beginning to catch up with scientific reality. The scientific community is unanimous in concluding that bite-mark evidence has no place in our courtrooms and has all too often been used to destroy the lives of innocent people, convicting them for crimes they had nothing to do with. Hopefully, this decision will be a turning point in purging unscientific and unreliable forensics, which has no place in any criminal trials, from our legal system.”
While Chaney has been out of prison for more than three years, Wednesday's ruling is an important one for his future. Being found "actually innocent" is one of the requirements imposed by Texas on those who seek compensation for the time they spent in prison after being wrongfully convicted. The state pays eligible exonerees $80,000 for each year they spent in prison in a lump sum in addition to annual annuity payments.
