A federal appeals court on Thursday delayed the execution of an Alabama inmate — just hours before he was to die by lethal injection for killing a police officer — in order to review lawyers' claims that it would be unconstitutional to execute him because he is no longer competent because of strokes and dementia, reports the Associated Press.

The 11th U.S. Circuit Court of Appeals issued the stay about seven hours before Vernon Madison, 65, was scheduled to die at 6 p.m. by lethal injection at a state prison in Atmore. The appellate court said it will hear oral arguments in Madison's case in June. The Alabama attorney general's office responded with an emergency motion to the U.S. Supreme Court, asking it to let the execution proceed before the death warrant expired at midnight.

Madison was convicted in the 1985 killing of Mobile police Officer Julius Schulte. Schulte had responded to a domestic call involving Madison. Prosecutors said Madison crept up and shot Schulte in the back of the head as he sat in his police car.

Attorneys for the Equal Justice Initiative say that strokes and dementia have left Madison frequently confused and disoriented and unable to understand his pending execution. They argued he has an IQ of 72, can no longer walk independently and at one point talked of moving to Florida because he believed he was going to be released from prison.