Oklahoma, which last week put on hold planned executions due to a mix-up with lethal injection drugs, used a drug not included in its official protocol in a convicted murderer's January execution, The Oklahoman newspaper reported on Thursday.
The state used bottles labeled potassium acetate to execute convicted murderer Charles Warner when it was supposed to have used potassium chloride, a drug used to stop the heart that is part of the state's protocol for lethal injections, the newspaper reported, citing state Corrections Department records.
Warner's final words included "my body is on fire," according to witnesses in the death chamber.
The state's attorney general and corrections officials declined comment on the report.
Oklahoma halted the scheduled Sept. 30 lethal injection execution of Richard Glossip when it discovered two hours before the execution it had received potassium acetate, which experts said is not on the lethal injection protocol of any state, instead of potassium chloride.
The Oklahoma Court of Criminal Appeals on Oct. 2 granted a state request to halt three upcoming executions so state officials can examine the drug mix-up.
"The state has a strong interest in ensuring that the execution protocol is strictly followed," Attorney General Scott Pruitt said earlier this week.
Oklahoma has overhauled its death chamber protocol after a lethal injection last year led to widespread criticism.
"We cannot trust Oklahoma to get it right or to tell the truth," said Dale Baich, one of the attorneys for Glossip.
Warner was the only inmate executed in the state since the troubled lethal injection of convicted murderer Clayton Lockett in April 2014 in which chemicals spewed in the death chamber from an improperly placed intravenous line.
Lockett could be seen twisting on the gurney after death chamber staff failed to place the intravenous line properly in a vein. The execution was called off but he died about 45 minutes after it started because lethal injection chemicals had accumulated in his tissue.
(Writing by Jon Herskovitz; Editing by Will Dunham)