SAVANNAH, Ga. - Georgia death row inmate Troy Anthony Davis failed to prove his innocence after the U.S. Supreme Court gave him a rare chance to clear his name, a federal judge ruled Tuesday.

The ruling by U.S. District Court Judge William T. Moore Jr. sets the stage for Georgia to resume plans for Davis' execution nearly 20 years after a Savannah jury sentenced him to death for the slaying of off-duty Savannah police officer Mark MacPhail.

In June, Moore heard two days of testimony from witnesses who sought to cast doubt on Davis' conviction. Some said they falsely incriminated Davis at his 1991 trial, either out of spite or under pressure from police. Others said they had heard another man confess to being MacPhail's killer.

In his ruling, the judge concluded, "while executing an innocent person would violate the United States Constitution, Mr. Davis has failed to prove his innocence."

Davis' sister, Martina Correia, isn't giving up hope.

"We will continue to fight. And we'll appeal," she said. "I have to talk to the lawyers and find out what the next steps are."

An attorney for Davis, Stephen Marsh, said they were still reviewing the ruling and had no immediate comment.

The U.S. Supreme Court ordered the evidentiary hearing for Davis a year ago. The move was extraordinary because federal death penalty appeals normally look only at questions of due process and violations of constitutional rights. Appeals based on condemned inmates' claims of innocence are routinely rejected.

A jury sentenced Davis, 41, to death for killing MacPhail, an off-duty police officer who was shot twice while rushing to help a homeless man being attacked outside a bus station.

The victim's mother, Anneliese MacPhail, said she was pleased by the ruling but nervous that it may not stick.

"I'm not holding my breath," said MacPhail, 76. "We've been through too much to think this is over soon. For 19 years we've been going back and forth, and too often in the 11th hour something happens."

Davis has been spared from execution three times as his attorneys pushed their argument that new evidence shows police ignored MacPhail's real killer as they rushed to pin the shooting on Davis.

Prosecutors argued Davis' lawyers were simply rehashing old testimony already rejected by a jury and blaming another man for the crime through hearsay accusations that no trial court would consider.

At the June hearing before Moore, two witnesses testified they lied at Davis' 1991 trial when they told jurors he confessed to the shooting. One said police pressured him into naming Davis as the killer.

Also, two men told the judge another man, Sylvester Coles, told them after the trial that he, not Davis, had been the shooter. However, the judge warned he might give little weight to their stories because Davis' lawyers didn't subpoena Coles to answer the accusation in open court. The judge barred a third witness with a similar story from testifying.

Davis' case has become a rallying point for death penalty opponents and groups such as Amnesty International and the NAACP. Dignitaries advocating that his case be reopened have included former President Jimmy Carter, Pope Benedict XVI and Nobel Peace Prize laureate Archbishop Desmond Tutu.

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