Story highlights The American Civil Liberties Union calls for greater transparency

A judge orders officials to preserve all physical evidence in Joseph Wood's execution

A media witness likens Wood's breathing to a "fish gulping for air"

Wood had argued combination for lethal injection was cruel and unusual punishment

Joseph Wood snorted and struggled to breathe during his nearly two-hour lethal injection Wednesday, his attorney said.

"It took Joseph Wood two hours to die, and he gasped and struggled to breathe for about an hour and 40 minutes. We will renew our efforts to get information about the manufacturer of drugs as well as how Arizona came up with the experimental formula of drugs it used today," attorney Dale Baich said in a statement.

He added: "Arizona appears to have joined several other states who have been responsible for an entirely preventable horror -- a bungled execution."

Arizona Gov. Jan Brewer had directed the Department of Corrections to review the process, saying she is concerned by the length of time it took to carry out the lethal injection.

A federal judge ordered local officials to preserve all physical evidence in Wood's execution.

"One thing is certain, however, inmate Wood died in a lawful manner and by eyewitness and medical accounts he did not suffer. This is in stark comparison to the gruesome, vicious suffering that he inflicted on his two victims -- and the lifetime of suffering he has caused their family," Brewer said.

Inmate Joseph Wood has been executed in Arizona.

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Arizona's corrections department said in a statement that it followed protocol in Wood's execution, re-affirming his "deep sedation" seven times before he was pronounced dead.

Aside from snoring, he did not make grimaces or otherwise move, the corrections department said.

Wood was convicted of murder and assault in the 1989 deaths of his estranged girlfriend and her father.

"I don't believe he was gasping for air; I don't believe he was suffering. It sounded to me like was snoring," said Jeanne Brown, a relative of Wood's victims.

"You don't know what excruciating is. What's excruciating is seeing your dad laying there in a pool of blood, seeing you sister laying there in a pool of blood. This man deserved it. And I shouldn't really call him a man," she said.

The execution procedure began at 1:52 p.m. (4:52 p.m. ET) and concluded, with Wood's being pronounced dead, at 3:49 p.m. (6:49 p.m. ET).

Troy Hayden, a media witness from KSAZ , told reporters the execution was difficult to watch. He likened Wood's breathing to a "fish gulping for air."

"It was tough for everybody in that room," he said.

Michael Kiefer, a reporter for The Arizona Republic, has witnessed five executions, including Wood's.

"Usually it takes about 10 minutes, the person goes to sleep. This was not that," he told reporters afterward. "It started off looking as if it was going alright but then obviously something didn't go right. It took two hours."

Kiefer described the sound Wood made as a "deep, snoring, sucking air sound."

Wood's 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 motion read: "He is still alive. This execution has violated Mr. Wood's Eighth Amendment right to be executed in the absence of cruel and unusual punishment. We respectfully request that this Court stop the execution and require that the Department of Corrections use the lifesaving provisions required in its protocol."

Inmate objected to drugs

Earlier, the Arizona Supreme Court lifted its brief stay of the murderer's execution.

Wood was first set 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 was 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.

Wood claimed 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.

Wood was "very concerned they were experimenting," said attorney Baich, who witnessed the execution.

"The room was silent. I was focusing on Mr. Wood. There were seven announcements during the process that Mr. Wood was still sedated. This is -- to confirm that he was still sedated.

"He was still breathing and struggling to breathe and gasping and snorting. I have witnessed 10 executions, and I had never seen that before," Baich told CNN.

Controversial Oklahoma execution

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.

"It's time for Arizona and the other states still using lethal injection to admit that this experiment with unreliable drugs is a failure," the American Civil Liberties Union said in a statement.

"Instead of hiding lethal injection under layers of foolish secrecy, these states need to show us where the drugs are come from. Until they can give assurances that the drugs will work as intended, they must stop future executions," it read.