The Georgia Supreme Court halted Monday's scheduled execution of a man convicted of killing a fellow prison inmate, turning aside his claim of mental disability and blocking the planned lethal injection on other grounds.

Warren Lee Hill had faced a scheduled 7 p.m. execution. But the high court said just hours beforehand it was unanimously staying the execution to consider his appeal challenging Georgia's recent switch to a single-drug execution method.

In a subsequent non-unanimous statement, the court denied Hill's request they review defense arguments that Hill should be spared because he is mentally disabled. The state has previously said Hill's defense lawyers failed to conclusively show a mental disability. Federal law prohibits states from executing the mentally disabled.

Hill was convicted in the Aug. 17, 1990, beating death of Joseph Handspike. Hill was serving a life sentence at the time for the shooting death of his 18-year-old girlfriend.

Hill's lawyers, among other issues, had challenged the state's recent switch from a three-drug lethal injection to a one-drug method. The change was announced days ago by state authorities.

Tags: death penalty, death row, stay, execution, execution drug, Warren Lee Hill, planned execution