In a statement Thursday, Gov. Mary Fallin said the mix-up came to light after state officials stopped the execution of Richard Glossip last week
because the state supplier had sent the Department of Corrections potassium acetate instead of potassium chloride (the drug approved as a part of the state's three-drug protocol).
"During the discussion of the delay of the execution it became apparent that DOC may have used potassium acetate in the execution of Charles Warner in January of this year," Fallin said. "I was not aware nor was anyone in my office aware of the possibility until the day of Richard Glossip's scheduled execution."
The governor said the state attorney general is now conducting an inquiry into the Warner execution.
She added: "Until we have complete confidence in the system, we will delay any further executions."
Fallin said that the pharmacist who provided the drug had assured the DOC that the drugs are medically interchangeable. But her critics note that potassium acetate is not officially part of the state's protocol.
"We cannot trust Oklahoma to get it right or to tell the truth," said Dale Baich, a lawyer for Glossip. "The execution logs for Charles Warner say that he was administered potassium chloride, but now the state says potassium acetate was used. We will explore this in detail through the discovery process in the federal litigation."
Oklahoma's difficulties began in April 2014, when Clayton Lockett died gasping for air, writhing on the table. After the botched execution, Fallin ordered a full review of the state's procedures, which took five months to complete. The state adopted a new protocol in September 2014.
In January 2015, Warner's execution took place and Fallin released a statement praising the "professionalism" shown by the Department of Corrections.
The Associated Press reported that Warner "showed no physical signs of distress" after the drugs were administered although he did say, "My body is on fire."
The new revelation has implications for the Supreme Court's recent opinion allowing the use of midazolam, the first drug in Oklahoma's protocol.
In a majority opinion authored by Justice Samuel Alito last June allowing the use of midazolam, the court referenced Lockett's botched execution but said Oklahoma had made changes and there were now "safeguards" in place with regard to the "training and preparation of the execution team."
Alito wrote: "In January of this year, Oklahoma executed Warner using these revised procedures and the combination of midazolam, a paralytic agent, and potassium chloride."
Justice Sonia Sotomayor wrote a biting dissent and Justices Stephen Breyer and Ruth Bader Ginsburg wrote separately to say for the first time that they thought the court should revisit whether the death penalty is unconstitutional.
The story was first reported by The Oklahoman newspaper