A DNA test on a single hair has cast doubt on the guilt of a Texas man put to death 10 years ago for a off-licence murder.
The execution went ahead after then governor George Bush's staff failed to tell him the condemned man was asking for genetic analysis of the strand.
The hair had been the only piece of physical evidence linking Claude Jones to the crime scene. But the recently-completed DNA analysis found it did not belong to Jones and instead may have come from the murder victim.
Barry Scheck, co-founder of the Innocence Project, a New York legal centre that uses DNA to exonerate inmates and worked on Jones' case, said the hair did not prove an innocent man was put to death.
But he said the findings meant the evidence was insufficient under Texas law to convict Jones.
Jones, 60, a career criminal who steadfastly denied killing off-licence owner Allen Hilzendager outside the town of Point Blank in 1989, was executed by lethal injection on December 7 2000, in the closing weeks of Mr Bush's term as governor and in the middle of the turbulent recount dispute in Florida that ended with him elected US president.
As the execution drew near, Jones was pressing the governor's office for permission for a DNA test on the hair. But the briefing papers Mr Bush was given by his staff did not include the testing request and Mr Bush denied a reprieve, according to state documents obtained by the Innocence Project.
Mr Scheck said he believed "to a moral certainty" that Mr Bush would have granted a 30-day reprieve had he known Jones was seeking DNA testing.
"It is absolutely outrageous that no-one told him that Claude Jones was asking for a DNA test," Mr Scheck said. "If you can't rely on the governor's staff to inform him, something is really wrong with the system."
Mr Bush had previously shown a willingness to test DNA evidence that could prove guilt or innocence in death penalty cases. Earlier in 2000, he had granted a reprieve to a death row inmate so Mr Scheck and other lawyers could have evidence tested. The test confirmed the man's guilt and he was executed.
A spokesman for Mr Bush, who is on a book tour, declined to comment yesterday.
The other primary evidence against Jones came from one of two alleged accomplices, Timothy Jordan, who did not enter the off licence but was believed to have planned the robbery and provided the gun.
Jordan gave evidence that Jones had told him he was the trigger man. But under Texas law, accomplice testimony is not enough to convict someone and must be supported by other evidence. The only other evidence was the hair.
But more than three years after the execution, Jordan recanted his claim that Jones admitted being the gunman. In an affidavit he said he was scared and "I testified to what they told me to say".
But Joe Hilzendager, the murder victim's brother, said: "I still think he was guilty. I think they executed the right man."
Former San Jacinto County sheriff Lacy Rogers also said he was convinced Jones committed the crime "without a doubt in my mind".
Authorities said Jones' his getaway driver was Danny Dixon, previously convicted of shooting a girl between the eyes and burying her in a cemetery.
During the trial a forensic expert said he examined the hair under a microscope and concluded that it could have come from Jones, but not from Dixon or the store owner. No DNA test was performed for the trial.
At the trial prosecutors stressed Jones' brutal past. While serving a 21-year prison sentence in Kansas, he poured a flammable liquid on his cellmate and set him on fire, killing him.
Jones was the last person put to death during Mr Bush's time as governor.