JACKSON, Georgia (Reuters) - Georgia is set to execute later on Wednesday a man convicted of murdering a police officer in one of the highest-profile U.S. capital punishment cases in years, depending on the success or failure of last-minute legal maneuvering.
The case of Troy Davis has attracted international attention and an online protest that has accumulated nearly a million signatures because of doubts expressed in some quarters over whether he killed police officer Mark MacPhail in 1989.
Davis is scheduled to die by lethal injection at 7 p.m. local time at Georgia's Diagnostic and Classification prison for the murder of MacPhail outside a Burger King restaurant in Savannah, Georgia, in 1989. MacPhail's family say Davis is guilty and should be executed.
"Our hearts go out to them (MacPhail's family). We have nothing but sympathy and prayers for them but they are not getting justice if the wrong person is paying for what happened to their son, their brother," civil rights leader Al Sharpton told reporters at the prison.
Since Davis's conviction, seven of nine witnesses have changed or recanted their testimony, some have said they were coerced by police to testify against him and some say another man committed the crime.
No physical evidence linked Davis to the killing.
Once a death warrant was signed, Davis's best hope of avoiding execution had rested with the Georgia Board of Pardons and Paroles but on Tuesday it denied him clemency following a one-day hearing.
On Wednesday, his lawyers requested a polygraph in a bid to halt the execution and show his innocence, but prison officials rejected the entreaty.
The lawyers also filed a motion to stay in the county where the execution is set to take place. That was denied and Georgia's Supreme Court later turned down an appeal, according to media reports.
Defense lawyers planned to appeal that ruling to the U.S. Supreme Court, said Sara Totonchi, executive director of the Southern Center for Human Rights.
Defendants in capital cases in Georgia are much less likely to face the death penalty if they can afford legal counsel and Davis was assigned a court-appointed lawyer who was overworked and underfunded, Totonchi said.
"Davis was poor, from a poor neighborhood and was given a court-appointed lawyer at a time when Georgia was providing next to no funding (for the defense in capital cases) ... He slipped through the cracks," she said.
Several hundred supporters of Davis rallied in a somber mood in a wooded area on the grounds of Georgia's Diagnostic and Classification Prison where the execution was set to take place under the watchful eye of dozens of prison officers.
They listened to speeches and chanted slogans such as: "Please don't let Troy Davis die" and "I am Troy Davis."
Editing by Jerry Norton and Eric Walsh