(CBS/WGCL/AP) ATLANTA - Hours before the scheduled execution of condemned Georgia inmate Troy Davis, the defense's last effort, a request for a polygraph, has been blocked, defense attorneys say.
Attorney Stephen Marsh told The Associated Press on Wednesday that the Georgia Department of Corrections has denied his request to allow Davis to take a polygraph test. Davis is scheduled to die at 7 p.m. EDT Wednesday.
Davis has long claimed he is innocent of killing Mark MacPhail, an off-duty police officer working as a security guard in Savannah, Ga. But state and federal courts have repeatedly upheld his conviction.
Prosecutors and MacPhail's relatives say they have no doubt the right man is being punished.
Marsh had said he hoped the polygraph test would convince the state pardons board to reconsider a decision against clemency.
Additionally, Davis' attorneys have filed a last-minute appeal in Butts County Superior Court, south of Atlanta.
The appeal argues that ballistic testing that linked Davis to the shooting was flawed. It also says that trial testimony of "jailhouse snitch" Kevin McQueen was "absolutely false." McQueen testified that Davis had confessed to him that he murdered Savannah police officer MacPhail, reports CBS affiliate WGCL.
Davis was convicted in 1991 and sentenced to death in the 1989 killing of MacPhail.
Davis' supporters are planning to rally at the prison in Jackson in the hours leading up to his death.
Davis didn't request a special last meal. He planned to spend his final hours meeting with friends, family and supporters.