(CNN) -- Inmate Joseph Wood has been executed, said Arizona Attorney General spokeswoman Stephanie Grisham. His attorneys had filed an emergency motion for a stay after his execution began, saying then that Wood had been "gasping and snorting for more than an hour."
The Arizona Supreme Court lifted its brief stay of a murderer's execution Wednesday morning, meaning a man who has argued against the constitutionality of the drugs meant for his injection still could be put to death later in the day.
Joseph Wood was to be executed at 10 a.m. local time (1 p.m. ET), though it was temporarily halted when the court said it would consider his request for the justices to review his claims.
The court lifted the stay shortly after that, saying without explanation that it considered the request but decided not to review Wood's case.
Wood is the latest American death row inmate to argue that an anesthetic recently introduced in some states' execution protocols could fail to sufficiently knock out the inmate ahead of the lethal drugs, subjecting the person to an agonizing death.
Arizona Department of Corrections spokesman Doug Nick said the execution could happen Wednesday afternoon, barring any other court orders.
Wood, convicted of murder and assault in the 1989 deaths of his estranged girlfriend and her father, argued among other things that the state was going to use an "experimental" drug protocol of midazolam and hydromorphone.
In documents filed with the state Supreme Court, he contended the use of the anesthetic midazolam was problematic in recent U.S. executions and that it would violate the Constitution's guarantee against cruel and unusual punishment.
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Drugs weren't Wood's only contention. He also argued the execution should be stopped because his trial attorney was ineffective and that new evaluations from psychologists show he has cognitive impairments that would make him innocent of premeditated murder.
Some states turned to midazolam this decade after they could no longer get sodium thiopental, a drug that was regularly used for executions. A U.S. manufacturer stopped producing sodium thiopental in 2009, and countries that still produce it won't allow its export to the United States for use in lethal injections.
Earlier this year, Oklahoma put executions on hold after the controversial execution of Clayton Lockett. Midazolam was part of the injection combination, and it took 43 minutes for him to die, Oklahoma officials said.
While state officials said Lockett was unconscious the entire time, a media witness for CNN affiliate KFOR said he uttered the words, "Man," "I'm not," and "something's wrong," before blinds to the execution chamber were closed. His lawyer, Dean Sanderford, said the inmate's body twitched and convulsed before he died.
Oklahoma's Department of Public Safety, acting on orders from Gov. Mary Fallin to get to the bottom of what happened, is investigating whether prison officials followed protocols. The review is also supposed to include recommendations about how to prevent something similar from happening again.