Sue Ogrocki, File, Associated Press
This Friday, July 25, 2014 file photo shows bottles of midazolam at a hospital pharmacy in Oklahoma City. In a March 4, 2015 letter, Akorn, the manufacturer of the drug used in Oklahoma’s lethal injection process, is asking the state to return any supplies it may have obtained and not to use its products to execute prisoners.

OKLAHOMA CITY — The Illinois-based manufacturer of a drug used in Oklahoma's lethal injection process is asking the state to return any supplies it may have obtained and not to use its products to execute prisoners.

In a letter to Oklahoma Attorney General Scott Pruitt, the drug manufacturer Akorn also said it was taking steps to ensure that the sedative midazolam no longer be made available to states for use in executions. The company said the painkiller hydromorphone, which Oklahoma doesn't use, also won't be available.

"If your prisons have purchased Akorn products directly or indirectly for use in capital punishment we ask that you immediately return our products for a full refund," Akorn's general counsel, Joseph Bonaccorsi, wrote in the March 4 letter.

Bonaccorsi and a company spokesman did not immediately return phone messages seeking comment Thursday.

Akorn is one of several manufacturers of midazolam, a common surgical sedative that Oklahoma began using last year as the first in a three-drug lethal injection protocol.

It is not clear if Oklahoma obtained its midazolam from Akorn. State officials are prohibited from revealing the source.

Pruitt spokesman Aaron Cooper referred all questions about the drug to the Department of Corrections, which is responsible for obtaining the drugs used in executions.

DOC spokeswoman Terri Watkins said the department had obtained the drugs necessary to carry out three executions that have been delayed while the U.S. Supreme Court considers whether the use of midazolam is appropriate for executions. She declined to comment further.

During oral arguments before the nation's highest court on Wednesday, an attorney representing the inmates argued midazolam is ineffective in preventing searing pain from one of the other drugs used in the process.

Death penalty states like Oklahoma have been forced to find alternative drugs to use for executions because of opposition to the death penalty from drug manufacturers. During oral arguments on Wednesday that lasted for more than an hour, conservative Justice Samuel Alito said death penalty opponents are waging a "guerrilla war" against executions by working to limit the supply of more effective drugs.

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