The cause of Georgia death row inmate Warren Hill, who faces execution next month, received national attention this week after a New York Times editorial called on the state to spare the mentally disabled man.

In an editorial titled "An Urgent Plea for Mercy," the New York Times on Friday wrote the state Board of Pardons and Paroles "has the discretion and the duty to commute his sentence to life without parole. The legal and factual record strongly compels that just decision."

Hill's death warrant was signed Monday, and a 7 p.m. execution by lethal injection is set for July 18 at the Georgia Diagnostic and Classification Prison in Jackson, unless Pardons and Paroles grants him clemency.

Hill, who was already serving a life sentence at the Lee Correctional Institution for killing his girlfriend, was convicted in 1990 of killing a fellow inmate with a nail-studded board.

Although a state judge found that Hill more likely than not was mentally disabled when he killed inmate Joseph Handspike, the Georgia Supreme Court reversed that ruling because it said Hill had not proven he was mentally disabled beyond a reasonable doubt. His execution was then ordered.

Georgia is the only state in the country that sets such a high burden of proof for capital cases involving defendants who claim mental retardation.

Hill's death sentence was upheld on appeal to the U.S. Circuit Court of Appeals. The U.S. Supreme Court also declined to review the case.

The Times editorial called the state Supreme Court's requirement of the higher burden of proof a "stark constitutional error." In urging clemency, it also noted that jurors in the case said they would have given Hill a life sentence if they'd had the option, and some members of Handspike's family also do not want him executed.

Brian Kammer, one of Hill's lawyers, said the Board of Pardons and Paroles will be asked for clemency before the July 18 execution date.

Staff writer Bill Rankin contributed to this report