Joseph Wood.

Joseph Wood died exactly as he had feared -- taking hours of prolonged agony.

The much-publicised execution of a convicted double murderer in Arizona took nearly two hours with the inmate gasping and snorting for long after the lethal injection was administered, according to media witnesses.

The Arizona governor Jan Brewer has ordered a review of the state's execution process.

"I've never witnessed an execution that took that long," Wood's federal public defender, Dale Baich, told NBC News. "The state of Arizona today conducted a failed experiment. ... It was horrible to watch."

The execution began with doctors inserting the IVs into Wood's veins. Joseph Wood, 55, thanked god and closed his eyes as the dose was administered. But after a few minutes, witnesses said, they could see something was wrong.

"It was almost like snoring," Associated Press reporter Astrid Galvan said. "It looked like he was yawning almost."

Wood went on to gasp more than 600 times over the course of an hour and 40 minutes, witnesses said.

Midway through the execution, Baich filed papers asking a federal court to stop the execution and order prison officials to try to resuscitate Wood. But before the court could act, Wood was pronounced dead.

"The state of Arizona was on notice," Baich said. "They knew that Ohio had used these two drugs back in January and they had problems with that execution. Why they used the same two drugs for Mr. Wood's execution I don't know."

While ordering a review, Gov Jan Brewer said, "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."

Wood was convicted for the cold-blooded 1989 murder of his girlfriend, Debra Dietz, and her father.

Wood was among five other death-row inmates who sued over concerns that executions would be carried out with the same drug used in the botched Oklahoma execution, midazolam. Wood had invoked his First Amendment right to know details about the state's lethal injection method, the qualifications of the executioner and the drugs manufacturers.

Upheld by the 9th US Circuit Court of Appeals which put a hold on the execution, the First Amendment argument did not hold water with the Supreme Court which ordered the execution on Wednesday.

The execution which the state carried out with a two-drug combination it had never before tried is sure to further raise public concerns over botched executions in the nation.

The American Civil Liberties Union called for a moratorium on executions until states can ensure that their lethal injections will work as intended.

"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 group 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."

Wood was put to death with a combination of midazolam and hydromorphone, the same drugs used in Ohio's execution of Dennis McGuire, who seemed to struggle for air and took 25 minutes to die.