MONTGOMERY, Ala. (AP) — Alabama’s prison commissioner did not explain what caused a lethal injection to be delayed for hours beyond saying staff members were being careful. But others say the delay was troubling and raises questions about what happened.

Joe Nathan James Jr. was put to death Thursday night for the 1994 murder of his ex-girlfriend, Faith Hall. He was pronounced dead more than three hours after the procedure originally was supposed to begin.

Alabama Corrections Commissioner John Hamm says “nothing out of the ordinary” occurred.

He says staff members were just being careful.

The head of the Death Penalty Information Center says such a time-lapse is highly unusual and very troubling.