An untested drug cocktail led to a botched execution of an Oklahoma prisoner on Tuesday night. Clayton Lockett's vein failed upon administration of drugs and the execution was halted after 20 minutes. He then suffered a "massive heart attack" and died. Lockett and another inmate, Charles Warner, were both set to be executed on Tuesday night after a string of hearings and appeals. Their lawyers argued that the state must disclose details of the drugs used, and the state Supreme Court issued a rare stay of execution. Warner was set to be put to death two hours after Lockett but has received a 14-day stay.