Mentally disabled, 54 year old Warren Hill is on death row in the state of Georgia where he is scheduled to die.
Hill will be executed at 7pm Tuesday, barring a US supreme court-issued stay.
Press TV reports: Hill was serving life in prison for the murder of his partner but was sentenced to death after he fatally beat a fellow prisoner in 1990.
Hill’s lawyers and advocates filed a petition with the US Supreme Court on Thursday to stop the execution based on his disability.
The victim’s family as well as multiple legal and medical organizations have also called for clemency.
But Georgia has maintained that the state requires proof beyond a reasonable doubt of that disability.
In 2002, the US Supreme Court ruled against the execution of mentally retarded prisoners, but left each state with the authority to determine the case.
“Every single expert who has examined him, including those retained by the state, agrees that Mr. Hill has intellectual disability,” his lawyer Brian Kammer said in a statement.
“Mr. Hill faces execution despite the fact that he has had lifelong, well-documented intellectual disability, which should exclude him from facing a death sentence,” he said.