LUCASVILLE, OH - Ohio inmate Dennis McGuire appeared to gasp several times and took as long as 15 minutes to die Thursday during his execution by lethal injection, reporters who witnessed it said.
He was convicted in 1994 of the rape and murder of Joy Stewart, whose relatives were at Southern Ohio Correctional Facility in Lucasville to witness his death, according to tweets from television reporter Sheila Gray.
McGuire's "children and daughter-in-law were crying and visibly upset," Gray tweeted.
The execution, at 10:53 a.m. ET, has generated controversy because, like many states, Ohio has been forced to find new drug protocols after European-based manufacturers banned U.S. prisons from using their drugs in executions -- among them, Danish-based Lundbeck, which manufactures pentobarbital.
The state used a combination of the drugs midazolam, a sedative, and the painkiller hydromorphone, the state corrections department told CNN.
In an opinion piece written for CNN earlier this week, a law professor noted that McGuire's attorneys argued he would "suffocate to death in agony and terror."
"The state disagrees. But the truth is that no one knows exactly how McGuire will die, how long it will take or what he will experience in the process," wrote Elisabeth A. Semel, clinic professor of law and director of the Death Penalty Clinic at U.C. Berkeley School of Law.
According to a pool report from journalists who witnessed the execution, McGuire took more than 15 minutes to die, and made "several loud snorting or snoring sounds."
Ohio ran out of pentobarbital in September, according to JoEllen Smith, the spokeswoman for the Ohio Department of Rehabilitation and Correction.
In response to that shortage, the department amended its execution policy to allow for the use of midazolam and hydromorphone.
The state was set to execute death row inmate Ron Phillips using the new drugs last year, but Gov. John Kasich granted the convicted killer a stay of execution pending a review of a possible organ donation to his family members.
There are currently 139 men and one woman on death row in Ohio, according to the corrections department website.