The execution of Clayton Lockett was halted after a doctor acknowledged that because of problems in administering the drugs , there were not enough left to carry out the death sentence , the Oklahoma Department of Corrections said Thursday . The revelation came as Oklahoma 's governor called for an investigation into the attempted execution that , according to some witnesses , left Lockett writhing in pain after a vein collapsed . A new and previously unused drug combination was reportedly used in the attempted execution . A timeline released by the state Department of Corrections details what occurred after Lockett 's execution was abruptly halted and a shade was lowered , blocking the view of witnesses . `` The doctor checked the IV and reported the blood vein had collapsed , and the drugs had either absorbed into tissue , leaked out or both , '' according to the timeline . The director of the corrections department then asked whether Lockett had been given enough of the drug combination to kill him , and the doctor said `` no . '' `` Is another vein available ? And if so , are there enough drugs remaining ? '' the doctor was asked , according to the timeline . The doctor 's answer to both questions : `` No . '' Lockett 's attempted execution was carried out Tuesday at the Oklahoma State Penitentiary in McAlester , where he had been housed following his conviction and death sentence for shooting Stephanie Nieman and then watching as two others buried her alive in 1999 . Lockett died from an apparent heart attack , 43 minutes after the execution began . The autopsy on Lockett , being conducted at Southwestern Institute for Forensic Science in Dallas , will take up to 12 weeks , Capt . George Brown of the Oklahoma Department of Prisons said . He did not offer an explanation for the length of time for the autopsy . According to the Oklahoma Department of Corrections , its execution protocol includes midazolam , which causes unconsciousness , vecuronium bromide , which stops respiration , and potassium chloride , which is meant to stop the heart . What follows is the Department of Corrections timeline of the execution : . -- At 5:22 p.m. local time , Lockett is restrained on the execution table . -- Between 5:27 p.m. and 6:18 p.m. , he is examined by a phlebotomist , who examines his arms , legs and feet for appropriate veins to administer drugs . -- At 6:18 p.m. , an IV is inserted into a vein in Lockett 's groin area , and his lower body is then covered with a sheet . -- At 6:23 p.m. , the curtain in the execution chamber is raised , and the doctor administers the first drug intravenously . -- At 6:30 p.m. , Lockett is still conscious . -- At 6:33 p.m. , the doctor declares Lockett is unconscious and begins to administer the second and third drugs . -- At 6:42 p.m. , the curtain is lowered . -- At 6:44 p.m. , the doctor checks the IV and reports Lockett 's vein has collapsed . -- Between 6:44 p.m. and 6:56 p.m. , the prison warden calls Department of Corrections Director Robert Patton and reports the information . The director asks the doctor a number of questions regarding Lockett 's condition : . The warden `` responded the doctor was checking the offender 's heart beat and found a faint heart beat and the offender was unconscious , '' according to the timeline . -- At 7:06 p.m. , Lockett is declared dead . There is nothing in the timeline that echoes the statements of witnesses , primarily journalists , who said 16 minutes into the execution Lockett was writhing in pain and appeared to be conscious . According to Courtney Francisco of CNN affiliate KFOR , Lockett seemed to try to get up and to talk , saying `` man '' aloud . Other reporters -- including Cary Aspinwall of the Tulsa World newspaper -- claimed that Lockett was `` still alive , '' having lifted his head while prison officials lowered the blinds , blocking the view of the proceedings . Charles Warner was scheduled to be executed later that night at the same prison . His execution has been postponed , at least temporarily . Lockett and Warner had been at the center of a court fight over the drugs used in their execution . They 'd initially challenged the state Department of Corrections ' unwillingness to divulge which drugs would be used . The department later disclosed the substances . Lockett and Warner also took issue with the state 's so-called secrecy provision forbidding it from disclosing the identities of anyone involved in the execution process or suppliers of any drugs or medical equipment . Oklahoma 's high court initially issued stays on their executions , only to lift those stays last week , ruling the two men had no right to know the source of the drugs intended to kill them .
Clayton Lockett 's execution in Oklahoma was halted two days after it began . Clayton 's vein collapsed as the drugs were administered , records show . A doctor said there were not enough drugs because Lockett had not been given enough drugs to kill him . The doctor also said there were not enough drugs to continue .