Murderer Warren Hill will die Monday evening unless his attorneys can find a court that believes his mental capacity is diminished enough that it would be unconstitutional to execute him, or if a judge finds fault with the state's new method of execution.

If he is executed as planned, Hill will be the first in Georgia to be put to death using only one drug — the powerful barbiturate pentobarbital — instead the three that the state has been using in combination since 2008.

Hill still has appeals based on the mental retardation issue pending in the Georgia and U.S. Supreme Courts. And on Monday a Fulton County Superior Court judge is scheduled to hear the issue of the Department of Corrections' sudden change in its lethal injection protocol from three drugs to one drug. Last Tuesday, the day before Hill was initially scheduled to die, the prison system announced it was abandoning the three-drug cocktail — a sedative followed by the paralytic pancuronium bromide and then potassium chloride, which stops the heart. It was replaced with a single drug process, pentobarbital, the same as in six other states [a seventh uses a different sedative].

Later, on Monday evening, there will be vigils held in 11 Georgia cites to express outrage that the state is executing a mentally retarded man.

"In other states, Hill would not face the ultimate punishment due to his disability," said Suzanne Nossel, executive director of Amnesty International USA."Unless the Supreme Court steps in to prevent this execution, the state of Georgia will have committed a terrible injustice."

Hill was condemned for using a nail-studded 2-by-6 board in 1990 to beat to death fellow prisoner Joseph Handspike. At that time Hill was already incarcerated for murdering his 18-year-old girlfriend.

The judge presiding over the 1991 trial for Handspike's murder found Hill, with an IQ of 70, was more likely than not to be mentally disabled. But the judge also determined that the lawyer representing Hill at the time had not proven his mental disability beyond a reasonable doubt, the standard set in 1988 when Georgia became the first state to prohibit executing the mentally disabled.

Since then, the U.S. Supreme Court said it has said it is unconstitutional to to execute the mentally retarded who are at "special risk of wrongful execution." But also in that 2002 decision, the justices left it up to the states to determine what was required to show mental retardation; Georgia has the strictest standard.

"Mildly mentally retarded individuals like Warren Hill frequently defy the stereotypical image we often have of persons with the disability in part because they tend to make efforts to hide the symptoms," wrote Hill's attorney, Brian Kammer. He said if a defendant can prove retardation beyond a reasonable doubt, then he is likely so severely retarded that if he went to trial the death penalty would not be an option. "He may even be found incompetent to stand trial. This leaves the majority of mentally retarded persons in the criminal justice system, who are mildly mentally retarded, in the lurch, because it is the mildly mentally retarded whose symptoms can mislead ... about the significance or even the existence of the disability."