The execution of a convicted murderer in Arizona lasted nearly two hours Wednesday, and witnesses said he gasped and snorted for much of that time before dying.

The drawn-out process prompted the governor to order a review, and it renewed criticism of lethal injection, the main method of execution in the United States, just months after a botched execution in Oklahoma.

Joseph R. Wood III was pronounced dead at 3:49 p.m., an hour and 57 minutes after the execution began at the Arizona State Prison Complex in Florence, the office of Arizona Attorney General Tom Horne said.

“I’ve witnessed a number of executions before, and I’ve never seen anything like this,” Dale Baich, one of Wood’s attorneys, said in a phone interview. “Nor has an execution that I observed taken this long.”

Wood was sentenced to death for the 1989 fatal shooting of his ex-girlfriend Debra Dietz and her father, Eugene.

During the execution, Wood’s attorneys filed a request to halt the lethal injection because he was awake more than an hour after the process began.

Shortly after the execution began, Baich said, Wood’s lips started to move, and he was “struggling to breathe.” Baich said he watched Wood “gasp and breathe heavily” for more than an hour and 40 minutes.

Reporters for the Associated Press and the Arizona Republic also reported seeing Wood gasp more than 600 times before dying. Michael Kiefer, a reporter for the Arizona Republic, said he counted 660 gasps, according to the newspaper. “I just know it was not efficient,” Kiefer said. “It took a long time.”

Charles Ryan, director of the Arizona Department of Corrections, said in a statement Wednesday night that Wood did not suffer during the execution.

Arizona Gov. Jan Brewer (R) ordered the Department of Corrections to conduct a review of the execution and said in a statement that she was “concerned by the length of time” it took.

Wood was the third inmate executed in Arizona since October and the first put to death using a combination of the drugs midazolam and hydromorphone.

Attorneys for Wood had argued that more information was needed regarding the drugs that would be used in the execution.

A panel of judges with the U.S. Court of Appeals for the 9th Circuit agreed with Wood over the weekend, staying the execution, and the full court upheld that decision Monday. But the U.S. Supreme Court vacated the stay and denied a stay request Tuesday evening.

Shortly before the scheduled execution, the state Supreme Court stayed the execution to consider his petition, but it later denied the request.