Arizona will no longer use the two-drug lethal injection cocktail it employed to execute a convicted killer in July after the man took almost two hours to die, the state’s prison chief said on Monday.

Charles Ryan said Arizona will instead use only one of the two drugs used in the cocktail. But those drugs have become difficult to obtain following the execution of Joseph Wood, who witnesses said struggled for breath after he was injected with 15 times the amount of drugs set out in state protocols.

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A three-drug combination also would be considered, Ryan said in a letter to outgoing Arizona Governor Jan Brewer, who called for the review into the July 23 execution.

The changes were outlined in a report by a consultant that reviewed Wood’s controversial execution, which critics said was botched and brought demands that procedures be changed.

The review found no wrongdoing by state officials.

“The report is clear that the execution of inmate Wood was handled in accordance with all department procedures, which … either meet or exceed national standards,” Ryan said in a statement. “It was done appropriately and with the utmost professionalism.”

Ryan said Wood was deeply sedated, and that as a result he “did not suffer.”

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Dale Baich, one of Wood’s attorney, said he wants the state to release more of the information that went into the review.

“The report released today does not answer the question of why the experimental drug protocol did not work as promised,” Baich said.

Wood was found guilty in 1991 of fatally shooting his former girlfriend Debbie Dietz, 29, and her father, Gene Dietz, 55, two years earlier at a Tucson automobile body shop.

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The complications in putting him to death, which followed two other lethal injections that went awry earlier this year in Ohio and Oklahoma, intensified debate over the death penalty and prompted Arizona to suspend executions pending the review.

Last week, Oklahoma Department of Corrections officials told a federal court that the state plans to continue using the same lethal injection drug combination which it used for the bungled execution of convicted murderer Clayton Lockett.

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(Reporting by David Schwartz; Editing by Daniel Wallis and Eric Beech)