ATLANTA -- After years of appeals and a recent wave of international protest surrounding his impending execution, Troy Anthony Davis has again reached the end of the line. His repeated claims of innocence have culminated into one final plea to the state Board of Pardons and Paroles, a five-member body here that is weighing clemency in Davis' case.

Supporters seeking to halt the execution descended on Atlanta this morning in a last-ditch effort to persuade the board. Davis' representatives were set to begin presenting their case at a 9 a.m. hearing.

The board has the sole authority in the state for granting clemency, and may commute Davis' death sentence to life without parole or life. It usually denies such requests, as it has in multiple cases this year. Georgia is one of just three states in which the governor does not have the authority to grant clemency.

Today's hearing is not open to the public or the media.

The board has not granted clemency since May 2008, when confessed killer Samuel David Crowe was spared just hours from his execution, said Steve Hayes, the board's director of public affairs.

Davis was convicted 20 years ago and sentenced to die for the 1989 slaying of Savannah, Ga., police officer Mark MacPhail, a Columbus High graduate whose mother still lives in Columbus. Davis has exhausted his appeals, and, should the pardons and paroles board turn him down, state officials intend to proceed with his execution at 7 p.m. Wednesday at the Georgia Diagnostic and Classification Prison in Jackson, Ga.

At issue today is the testimony of several witnesses who have recently changed or recanted their original statements to authorities.

"I think what's very troubling is there really is no physical evidence that links Troy directly to this crime, and that seven of nine witnesses have recanted or changed their testimony is very compelling because the case relied so heavily on witness testimony," Laura Moye, head of Amnesty International's Death Penalty Abolition Campaign, said in an interview this morning. "If he is not granted clemency today, we won't be going away. We're not going to sit by if the state of Georgia does plan to carry out an execution. We will continue to raise our voices and say, 'Not in my name.'"

Hundreds of thousands of people have signed petitions urging the board to spare Davis because of their doubts about his guilt, and prominent figures such as former President Jimmy Carter and Pope Benedict XVI have called for a new trial.

"Rather than make the wrong decision, rather than take a chance of killing a person with too much doubt in front of you, the world is saying to the parole board, ?Stop,'" said Ed DuBose, president of the Georgia State Conference of the NAACP, which held a support rally in Columbus for Davis last week. DuBose said he expects some Davis supporters from Columbus to come to Atlanta today.

Family members of MacPhail, meanwhile, say they have no doubt the right man is on death row.

"They keep trying their best to prove his innocence and there's nothing there. He was found guilty and he is still guilty.," said Joan MacPhail, Mark MacPhail's widow. "I think Amnesty International has done their business to give Davis a falsehood that he's going to be exonerated or going to have a commuted sentence or whatever they're trying to accomplish, which is abolish the death penalty.

"I think that when Wednesday is done with, they're going to leave them high and dry and the death is going to settle, and what's next?"

Davis, for his part, has long maintained he did not fire the shots that killed MacPhail. DuBose said he has visited Davis on death row and is convinced of his innocence. "Troy Davis tells the same story the same way each time," he said.

Some Davis supporters say another man with Davis the night of the shooting was responsible for MacPhail's death.

But last year, Judge William T. Moore Jr. of U.S. District Court dismissed the witness recantations as lacking credibility, adding Davis' new evidence amounted to little more than "smoke and mirrors." Moore wrote that "? while executing an innocent person would violate the United States Constitution, Mr. Davis has failed to prove his innocence."

Moore's ruling came after a rare evidentiary hearing ordered by the U.S. Supreme Court, which has since denied a final appeal from Davis.

"I think people are losing sight of things through this process," said Randy Robertson, vice president of the state Fraternal Order of Police, and a close friend of MacPhail's mother, Anneliese MacPhail. "They're thinking of the death penalty, and all we're looking at is the justice that comes with it.

Joan MacPhail said she and her family "wouldn't miss (today's hearing) for the world."

"We believe that the justice system will do what it's designed to do," she said. "Even though they've given Troy so many opportunities to prove his innocence, time and time he hasn't. So I think this is it. I don't really see us going anywhere further."

She added, "I really do believe that we are going to have some closure. ? You can't replace that loss, but I do believe we are actually going to have justice served at this time."

McClatchy-Tribune News Service