Georgia Dept. of Corrections, File, Associated Press
FILE - This undated file photo provided by the Georgia Department of Corrections shows convicted murderer Warren Lee Hill. The Georgia death row inmate who has come within hours of execution three times is once again scheduled for execution this week

ATLANTA — A Georgia death row inmate who has come within hours of execution three times is once again scheduled to die this week.

Warren Lee Hill, 54, who was sentenced to death in August 1991, was first scheduled to die two and a half years ago. Challenges filed by his lawyers have provided temporary reprieves on three occasions and twice have effectively halted all executions in Georgia for months at a time.

His case has also drawn national attention to Georgia's toughest-in-the-nation standard for death row inmates to prove intellectual disability in order to be spared execution on those grounds. State law and a 2002 U.S. Supreme Court ruling prohibit the execution of the intellectually disabled, but Georgia requires proof beyond a reasonable doubt of that disability.

Hill was sentenced to death in Lee County for the 1990 beating death of fellow inmate Joseph Handspike. At the time Hill was already serving a life sentence for murder in the 1986 slaying of his girlfriend.

Hill began exhibiting signs of intellectual disability at an early age, and all doctors who have examined Hill now agree he's intellectually disabled, Hill's lawyers have argued. The state has consistently argued Hill's defense has failed to prove beyond a reasonable doubt that he is intellectually disabled, and Georgia's strictest-in-the-nation standard has repeatedly been upheld by state and federal courts.

Hill has a mild intellectual disability, giving him the emotional capacity of an 11-year-old, Brian Kammer, a lawyer for Hill told The Associated Press.

"That's who we're going to execute if we execute Warren Hill — a boy in a man's body," Kammer said. "An 11-year-old can write letters and can talk articulately at times, but we don't expect an 11-year-old to be able to handle difficult situations without help."

Lawyers for the state have repeatedly argued Hill is not intellectually disabled, saying he provided for his family from an early age and was a recruiter in the military, in addition to other evidence.

A U.S. Supreme Court opinion from May that invalidated a Florida law said people facing the death penalty must have a fair opportunity to show the Constitution prohibits their execution.

Hill's lawyers argued that decision also invalidates Georgia's strict standard because psychiatric diagnoses are subject to a degree of uncertainty that is virtually impossible to overcome.

The state's lawyers reject that argument, saying Georgia's the burden of proof is not in conflict with the U.S. Supreme Court decision and that the high court in its 2002 decision left that up to the states.

Hill still has a federal appeal pending, and his lawyers are also asking the U.S. Supreme Court to consider his arguments based on the high court's ruling in the Florida case. He also has a clemency hearing Monday before the State Board of Pardons and Paroles, the only entity in Georgia that can commute a death sentence to life without parole.

Hill was first set for execution in July 2012. But the day before he was set to die, the state announced it was changing its execution method from a three-drug combination to a single drug injection and reset his execution for about a week later.

Hill's lawyers filed challenges to the state's last-minute switch in execution protocol, saying that change required a public hearing before it could be instituted under existing administrative procedures. The Georgia Supreme Court halted the execution less than two hours before Hill was to be put to death to give the justices time to consider that challenge.

Executions in Georgia were effectively put on hold for about six months while that challenge was pending.

The Georgia Supreme Court ruled in February 2013 that the execution method change was legal. The next day, a new execution date two weeks later was set for Hill.

Days before the execution was set to happen, Hill's lawyers submitted statements from the three doctors who examined Hill in 2000 and testified at his trial that he was not intellectually disabled. The doctors wrote in new statements that they had been rushed at the time of Hill's trial and new scientific developments had surfaced since then. All three reviewed facts and documents in the case and wrote that they believed Hill is intellectually disabled.

As Hill was being prepared for lethal injection, an 11th Circuit panel issued a stay to give the judges time to review the new doctor statements. The three-judge panel cited procedural rules in an April 2013 ruling rejecting Hill's request to submit his case to a federal court for reconsideration based on the new statements.

Hill's third scheduled execution date was in July 2013. A Fulton County Superior Court judge issued a temporary stay to consider Hill's challenge to a new state law prohibiting the release of information about the source of Georgia's supply of lethal injection drugs. The Georgia Supreme Court in May upheld that law.

Executions were effectively stopped for about 10 months while that challenge was considered.

He is now set to be executed at 7 p.m. Tuesday.