Alabama’s execution of a man convicted in the 1988 murder-for-hire slaying of a preacher’s wife was called off Thursday just before the midnight deadline because state officials couldn’t find a suitable vein to inject the lethal drugs.

Alabama Department of Corrections Commissioner John Hamm said prison staff tried for about an hour to get the two required intravenous lines connected to Kenneth Eugene Smith, 57. Hamm said they established one line but were unsuccessful with a second line after trying several locations on Smith’s body. Officials then tried a central line, which involves a catheter placed into a large vein.