Troy Davis has been scheduled to die on Georgia's death row three previous times. Friday night at an Atlanta rally and march, Davis' supporters said this time will be different.

Their numbers were greater, their voices are louder and they are hopeful that their appeals for clemency will be answered by the Georgia Board of Pardons and Paroles.

Hundreds of supporters marched through the downtown streets of the Georgia capital chanting "Free Troy Davis." Others carried signs that read, "Too Much Doubt."

However, unless something dramatic happens, Davis, 42, will die by lethal injection on Wednesday for the 1989 murder of Savannah police officer Mark MacPhail.

The case has drawn international attention. Davis' advocates say he was convicted on flimsy evidence.

Since his 1991 conviction, seven of the nine witnesses against him have recanted or contradicted their testimony. No physical evidence was presented linking Davis to the killing.

One of Davis' sisters told CNN she had spoken to him Friday, and that he was moved by the show of support. His family has maintained he is innocent.

"Someone asked us if had started making preparations for his final days," Kimberly Davis said. "We are not. We have actually (been) looking past those final days."

Hope is just about all Davis has right now. The pardons and paroles board denied him clemency once before. The board has never changed its mind in any case for the past 33 years.

On Thursday, supporters delivered to the pardons and paroles board a 663,000-name petition asking for clemency.

MacPhail's family has steadfastly asserted that Davis was the killer, as has the man who prosecuted him.

"I'm just disappointed so many people have been led to believe nobody has paid attention to these recantations. It is simply not the case," former Chatham County District Attorney Spencer Lawton once told CNN affiliate WTOC.

"On what grounds are the recantations more believable than the testimony in court? None."

Reviewing Davis' claims of innocence last year, the U.S. District Court for the Southern District of Georgia found that Davis "vastly overstates the value of his evidence of innocence."

"Some of the evidence is not credible and would be disregarded by a reasonable juror," Judge William T. Moore wrote in a 172-page opinion. "Other evidence that Mr. Davis brought forward is too general to provide anything more than smoke and mirrors," the court found.