ATLANTA Supporters of Georgia death row inmate Troy Davis on Thursday delivered petitions bearing 638,000 signatures to a state parole board that will decide next week whether to stop the condemned man's execution.
Davis, 41, was convicted of killing a Savannah police officer in 1989 and is due to be executed on September 21.
"There are incredible doubts that still remain," said Wende Gozan Brown, a spokeswoman for Amnesty International, one of the groups organizing the effort to halt the execution.
The Davis case has attracted international attention with former President Jimmy Carter and retired South African Archbishop Desmond Tutu among leaders who have expressed support for his clemency.
Davis was sentenced to death in Georgia's Chatham County for the murder of police officer Mark MacPhail, who was shot dead near a Burger King restaurant in Savannah. Davis' lawyers say it was a case of mistaken identity.
Amnesty International said some witnesses had recanted testimony used to convict Davis, and added there was "basically no physical evidence that links Davis to the crime".
Georgia's Board of Pardons and Paroles is scheduled to hold a clemency hearing on the case on Monday. The board has the power to commute the death sentence to life in prison or life without parole.
On Friday, Davis' supporters will hold a march in downtown Atlanta and a prayer service at Ebenezer Baptist Church, where the late Reverend Martin Luther King Jr. was pastor.
In an opinion column published Thursday in the Atlanta Journal Constitution newspaper, former FBI Director William Sessions called for Davis' sentence to be commuted to life in prison, saying the case was "permeated in doubt."
In an opposing column written in late 2008 and republished
on Thursday, Spencer Lawton, the district attorney who prosecuted Davis, wrote that the condemned man had a fair trial. The claim that seven witnesses in the trial had recanted their testimony was "not believable," Lawton wrote.
Lawton said the witnesses were all cross-examined by defense attorneys during Davis' trial and denied that they had been coerced by police.
Crime lab tests proved that shell casings recovered from an earlier shooting linked to Davis were fired from the same gun as casings found at the murder scene of the Savannah police officer, the former district attorney wrote.
(Editing by Colleen Jenkins and Cynthia Johnston)