ATLANTA — A federal appeals court gave a last-minute reprieve Friday to a Georgia man set to be executed for the 1989 killing of an off-duty police officer even though several witnesses have changed their accounts of the crime.

Troy Davis, 40, was scheduled to be executed Monday. But the three-judge panel of the 11th U.S. Circuit Court of Appeals ordered defense attorneys and prosecutors to draft briefs that address whether Davis can meet "stringent requirements" to pursue the next round of appeals.

Davis' supporters have called for a new trial because seven of the nine key witnesses against him have recanted their testimony, and the doubts about his guilt have won him the support of former President Jimmy Carter and other prominent advocates.

"I'm ecstatic. This movement is building and building and building," said Martina Correia, Davis' sister. "This is going to crumble the justice system in Georgia if they don't do the right thing."

Savannah Officer Mark MacPhail was working off-duty as a security guard at a bus station when he rushed to help a homeless man who had been pistol-whipped at a nearby parking lot. He was shot twice when he approached Davis and two other men.

Witnesses identified Davis as the shooter, and prosecutors at the 1991 trial said Davis wore a "smirk on his face" as he fired the gun.

But Davis' lawyers say new evidence proves their client was a victim of mistaken identity. Besides those who have recanted their testimony, three others who did not testify have said Sylvester "Red" Coles — who testified against Davis at his trial — confessed to the killing.

Coles refused to talk about the case when contacted by The Associated Press during a 2007 court appearance and has no listed phone number.

Prosecutors have said the case is closed. In court hearings, they said some of the affidavits repeat what a jury trial already has heard, while others are irrelevant because they came from witnesses who never testified.

Savannah District Attorney Spencer Lawton also said he doubts the new testimony meets the legal standards for a new trial. And while the recantations may seem persuasive to some, Lawton said, "to others of us it invites a suggestion of manipulation, making it very difficult to believe."

Georgia's pardons board postponed Davis' execution in 2007 less than 24 hours before it was to be carried out.

Over the next few months, a divided Georgia Supreme Court twice rejected Davis' request for a new trial, and the pardons board turned down another bid for clemency after considering the case again.

Then, two hours before his scheduled Sept. 23 execution, the Supreme Court issued a stay, sparking a celebration among Davis' supporters gathered outside the state prison. But the court cleared the way for the execution this month when it decided against giving Davis another hearing.

His supporters have tried to ratchet up the public relations campaign by holding rallies in Paris, Montreal, Brussels, London and Milan. The European Union's legislature issued a statement this week warning that Davis' execution is a "great risk of miscarriage of justice."

Lawton, though, contended the real victim of the high-profile campaign has been MacPhail's family. They have lived through a succession of legal challenges that have also tested "their faith and hope" since Davis' conviction 17 years ago, he said.

"For every minute of that time," he said, "Officer MacPhail's family has suffered the agony of uncertainty."