By Josh Sanburn
Updated: October 1, 2015 3:40 PM ET

Oklahoma Gov. Mary Fallin stayed the execution of death row inmate Richard Glossip Wednesday after the state’s Department of Corrections received a drug that was not in its official lethal injection protocol, the governor’s office said Thursday.

The execution of Glossip, which would’ve been the first since the Supreme Court upheld Oklahoma’s lethal injection protocol in June, was delayed at the last minute after the DOC alerted the governor that it had received potassium acetate instead of potassium chloride. The state’s current protocol includes potassium chloride, rocoronium bromide and midazolam, a controversial sedative that was at the heart of the recent Supreme Court case.

“I still don’t know why we had potassium acetate,” said Alex Gerszewski, an Oklahoma Department of Corrections spokesperson, in an email. “We can’t discuss how we obtain the drugs.”

Alex Weintz, a spokesperson for Gov. Fallin, said that the governor’s office has been told potassium acetate could be used as a potential substitute for potassium chloride but halted the execution because it wasn’t in the state’s current drug protocol. On Thursday, Oklahoma Attorney General Scott Pruitt asked the state’s court of criminal appeals to stay all upcoming executions in order to determine how the state obtained the drug.

“The state owes it to the people of Oklahoma to ensure that, on their behalf, it can properly and lawfully administer the sentence of death imposed by juries for the most heinous crimes,” Pruitt said in a statement. “Until my office knows more about these circumstances and gains confidence that DOC can carry out executions in accordance with the execution protocol, I am asking the Oklahoma Court of Criminal Appeals to issue an indefinite stay of all scheduled executions.”

Mark Heath, a Columbia University anesthesiologist who studies lethal injection, says that potassium acetate has never been used in an execution or included as part of a lethal injection protocol in the U.S.

The incident is the latest in a string of ongoing complications states are having in obtaining lethal injection drugs. A number of states have turned to previously unused drugs like midazolam after pharmaceutical companies halted sales of drugs like sodium thiopental—which was used in executions for years—to departments of corrections. Some states are getting drugs from compounding pharmacies, which are not regulated by the federal government, while others are looking overseas. Nebraska is attempting to import sodium thiopental and pancuronium bromide from India, but federal authorities have held up the shipment.

In April, the Supreme Court upheld Oklahoma’s drug protocol in a 5-4 ruling after Glossip and several other inmates argued that the use of midazolam violated the Eighth Amendment. The drug has been a part of several executions widely considered botched, including the April 2014 lethal injection of Clayton Lockett.

In 1997, Glossip was convicted of hiring Justin Sneed to kill Barry Van Treese, an Oklahoma motel owner. Glossip’s conviction was based largely on the testimony of Van Treese, who received a life sentence for implicating Glossip in the murder. But Glossip’s lawyers have since questioned Sneed’s testimony and have obtained statements from inmates who have spent time with Sneed suggesting that he may have acted alone in Van Treese’s death. Glossip had been appealing his death sentence, but those appeals were all denied.

Gov. Fallin issued a 37-day stay of execution for Glossip, which makes his next execution date Nov. 6.

“It is mind-boggling that a state could get something this basic wrong in a high-profile execution following a Supreme Court challenge to a state’s execution protocol,” said Robert Dunham, executive director of the Death Penalty Information Center, which advocates for more transparency in the execution process. “There is no excuse for a state to be so unprepared to carry out an execution.”

Contact us at editors@time.com.

SPONSORED FINANCIAL CONTENT

Read More From TIME

EDIT POST