Convicted killer to be executed in Georgia ATLANTA (Reuters) - Georgia will execute a two-time convicted killer on Tuesday if appeals based on the state's ban on capital punishment for those labeled "mentally retarded" fail. Warren Lee Hill, 52, killed a fellow prisoner, Joseph Handspike, in August 1990 by beating him to death. Hill was serving a life sentence for the 1986 shooting death of his 18-year-old girlfriend, Myra Wright. In a series of appeals, Hill's attorneys have argued his execution should be halted because he suffers from what they termed mental retardation. In 1988, Georgia became the first U.S. state to enact a law banning the execution of mentally retarded defendants. But according to death penalty experts, Georgia has perhaps the toughest standard in the nation for defining mental retardation, requiring proof "beyond a reasonable doubt." Last week, Brian Kammer, one of Hill's attorneys, filed affidavits in a Georgia court by three doctors who evaluated Hill for the state 13 years ago and now believe after further review that he is mentally retarded. "There is now unanimous consensus among all experts who have evaluated Mr. Hill over the last 22 years," Kammer told Reuters on Monday. Mr. Hill should be deemed to have met Georgia's uniquely stringent burden of proof for proving mental retardation. However, in court documents, the state of Georgia says the three state doctors reviewed "extensive materials" before concluding in 2000 that he was not mentally disabled, and were thoroughly cross-examined by Hill's attorneys at the time. The doctors noted in 2000 that Hill had been a recruiter for the U.S. Navy, budgeted his money and was a "father figure" for his siblings, the state said in court documents. In the new affidavits, one doctor called the earlier evaluation of Hill "extremely and unusually rushed" while another said his opinions of Hill in 2000 were "unreliable because of my lack of experience at the time." A third doctor cited "advances in the understanding of mental retardation" since 2000 as a reason for changing his findings. Hill's execution, scheduled for 7 p.m. EST, would be the second this year in the United States, according to the nonprofit Death Penalty Information Center. Georgia delayed Hill's execution last summer as it announced the switch from a three-drug cocktail that included the sedative pentobarbital to pentobarbital alone. Georgia officials did not say what prompted the change to the single drug. But in a legal challenge, Kammer said Georgia's supply of pancuronium bromide - one of the three drugs previously used in lethal injections - expired on July 1. Kammer argued corrections officials did not give the required notice under state law of the change, depriving his client adequate time to review the new procedure. The Georgia Supreme Court turned down the appeal on February 4. There are two executions in the United States scheduled for Thursday, one in Georgia and a second in Texas, according to the Death Penalty Information Center. Editing By David Adams and Alden Bentley