 -- An inmate's execution with lethal drugs in Arizona Wednesday took almost two hours as witnesses reported the man gasped and snorted, prompting his lawyers to request an emergency halt to the procedure.

"The execution of Joseph Wood commenced at 1:57 p.m. at the Arizona State Prison Complex (ASPC)-Florence and he was pronounced dead at 3:49 p.m.," Arizona Attorney General Tom Horne said in a statement.

Wood's attorneys filed a motion for emergency stay of the execution after Wood was reported “gasping and snorting for more than an hour,” according to court documents they filed. Justice Anthony Kennedy denied the appeal about a half hour after Wood's death, the Associated Press reported. An AP reporter who witnessed the execution saw Wood gasp more than 600 times before he died.

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"The experiment using midazolam combined with hydromorphone to carry out an execution failed today in Arizona," said Dale Baich, one of Joseph Wood’s attorneys.

Gov. Jan Brewer issued this statement: “I am concerned by the length of time it took for the administered drug protocol to complete the lawful execution of the convicted double murderer, Joseph Wood. While justice was carried out today, I directed the Department of Corrections to conduct a full review of the process.

“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, 55, was convicted of two counts of first-degree murder February 25, 1991, and sentenced to death July 2, 1991.

Wood was involved in an unstable five-year relationship with his ex-girlfriend, Debbie Dietz, during the time of the crime. On August 7, 1989, Wood walked into the local body shop owned by her family and shot Debbie’s 55-year-old father, Gene Dietz, in the chest with a .38 caliber revolver, according to a statement from the AG.

Wood later located Debbie, and shot her once in the abdomen and once in the chest, killing her as well, the document stated.

Jeane Brown, sister of Debbie Dietz, said at the press conference that "it’s been a long 25 years. Horrible 25 years. What I saw today, with him being executed, is nothing to the day it happened on August 7th, 1989. This was nothing. I don’t believe he was gasping for air, I don’t believe he was suffering. Sounded to me as though he was snoring. Finally it has come to a point in his life, where we can put this behind us, and continue to move forward although I still have to live the rest of my life without my sister and my father."

An Associated Press reporter who witnessed the execution said: "Mr. Wood was gasping for air in 5-12 second intervals for almost two hours. An hour and fifty minutes. It was almost like snoring – it looked like he was yawning almost, that’s how it looked, without sound."

Michael Kieffer, a witness from the Arizona Republic, told reporters that this was the fifth execution he's attended. "Usually takes about 10 minutes, person goes to sleep. This was not that. This looked like that at the beginning, for maybe the first 5-7 minutes he closed his eyes. He went to sleep. Then he started gasping, and he did, for an hour and half...As he would open his mouth, you could see his chest move – it would go all the way down to his stomach. It was a clear gasp. It looked like a fish opening and closing his mouth."

But Stephanie Grisham, the press secretary for state's AG, said in an email that the claims being made by the media witnesses and defense attorneys are not accurate. "He went to sleep, and looked to be snoring. This was my first execution and I was surprised by how peaceful it was. There was absolutely no snorting or gasping for air."

Wood's case highlighted scrutiny surrounding lethal injections after two controversial executions, including that of an Ohio inmate in January who snorted and gasped during the 26 minutes it took him to die. In Oklahoma, an inmate died of a heart attack minutes after prison officials halted his execution because the drugs weren't being administered properly, the Associated Press reported.

States have refused to reveal details such as which pharmacies are supplying lethal injection drugs and who is administering them, because of concerns over harassment.

Wood filed several appeals that were denied by the U.S. Supreme Court, including one on the basis that his First Amendment rights were violated when the state refused to reveal details of his execution such as the supplier of the drugs.

The Arizona Supreme Court also delayed the execution Wednesday morning to consider a last-minute appeal about whether Wood received inadequate legal representation at his sentencing. But about an hour later, the state's high court allowed the execution to proceed, the AP reported.

Wood argued he has a First Amendment right to details about the state's method for lethal injections, the qualifications of the executioner and who makes the drugs. Such demands for greater transparency have become a new legal tactic in death penalty cases.

The 9th U.S. Circuit Court of Appeals had put the execution on hold, saying the state must reveal the information. But the Supreme Court has not been receptive to the tactic, ruling against death penalty lawyers on the argument each time it has been before justices.

According to authorities, these were Wood's last words: “First I’d like to say thank you to Julie, Kevin, Dale, Deacon Ed and your offices who did everything to keep me from coming to this. I’m truly thankful – but when I accepted Jesus Christ as my savior in 2007, I knew this day would come. I am ok. I know whatever happens, I’ll be with my savior Jesus Christ and I take comfort in knowing that today my pain stops. I said a prayer, that on this, or any other day, you may find peace in your hearts. And may God forgive all of you.”

Richard Brown, a witness to the shooting and husband of Jeanne Brown, told reporters that "these people that do this, that are on death row, they deserve to suffer a little bit. This guy has been here for 25 years – getting medication, eating, roof, clothes, shoes - where’s them? They’ve been dead for 25 years. I saw the life go out of my sister-in-law’s eye as he shot her to death."

With reporting by ABC News' Ariane DeVogue. The Associated Press contributed to this report.