OKLAHOMA CITY (AP) - A report on a problematic execution in Oklahoma shows lethal drugs caused death row inmate Clayton Lockett to die, not a heart attack, after the State Corrections Director halted efforts to put him to death.

DOC Director Robert Patton had said inmate Clayton Lockett died from a heart attack several minutes after he ordered the execution stopped. In an autopsy report released Thursday, examiners from the Southwestern Institute of Forensic Sciences at Dallas conclude that all three execution drugs were found throughout Lockett's system. They declared that the cause of death was 'judicial execution by lethal injection'. The report indicates Lockett was poked several times as medical technicians tried to find a vein before using one at his groin.