(CN) - Oklahoma prison officials abruptly halted back-to-back executions Tuesday after the injection of controversially sourced drugs caused a murderer to writhe in apparent agony and then die from a heart attack.
Clayton Lockett, 38, was convicted in 2000 of the rape and murder of Stephanie Neiman, 19. He was convicted of shooting her with a sawed-off shotgun and watching two accomplices bury her alive.
Lockett persuaded the Oklahoma Court of Criminal Appeals to delay his March 27 execution date, claiming the state was buying execution drugs of unknown content from unlicensed compounding pharmacies.
Three drugs are needed for the state's lethal injections: pentobarbital to knock the inmate unconscious, vecuronium to stop breathing and potassium chloride to stop the heart.
The state acknowledged in a March 17 filing that its "Herculean" efforts to obtain the necessary drugs had failed. The nationwide shortage of execution drugs is a result of anti-death penalty advocates pressuring large drug manufacturers to stop their production, resulting in prison officials asking smaller, compounding pharmacies to produce substitute drugs.
Lockett was declared unconscious Tuesday after an injection of midazolam in the state's new three-drug combination, The Associated Press reported.
Three minutes later, Lockett began breathing heavily, writhing, clenched his teeth and strained to lift his head off of a pillow. Blinds separating a viewing gallery and the death chamber were lowered and Oklahoma Department of Corrections Director Robert Patton halted the execution 20 minutes later.
Lockett died of a heart attack shortly after. Lockett's attorney, David Autry, told the AP the execution was "totally botched."
"It was a horrible thing to witness," Lockett told the AP. "They should have anticipated possible problems with an untried execution protocol. Obviously, the whole thing was gummed up and botched from beginning to end. Halting the execution obviously did Lockett no good."
Autry was skeptical of Patton's explanation that one of Lockett's veins had blown.
"I'm not a medical professional, but Mr. Lockett was not someone who had compromised veins," Autry said. "He was in very good shape. He had large arms and very prominent veins."
Hours before Lockett's execution, Oklahoma Attorney General Scott Pruitt criticized Lockett's attorneys' "false claims" that the state had refused to provide them basic information about the execution drugs.
"The attorneys have not challenged the execution protocol in court, and instead have only made accusations in the media," Pruitt said in a statement Tuesday afternoon. "This would seem to indicate their acknowledgement a challenge of the execution protocol would be futile as the protocols are in fact constitutional."
Charles Warner was scheduled to die two hours after Lockett. Warner was convicted in 1999 of the rape and murder of Adrianna Waller, the 11-month-old daughter of his then girlfriend.
Oklahoma Gov. Mary Fallin stayed Warner's execution for 14 days and ordered an investigation of Lockett's execution.