LUCASVILLE, Ohio (AP) — An Ohio inmate condemned to die appeared to gasp several times during his prolonged execution Thursday with the first use of a lethal injection process never before tried in the U.S. 
 
 Death row inmate Dennis McGuire made several loud snorting or snoring sounds during the more than 15 minutes it appeared to take him to die. It was one of the longest executions since Ohio resumed capital punishment in 1999. 
 
 Ohio officials used intravenous doses of two drugs, the sedative midazolam and the painkiller hydromorphone, to put McGuire to death. The method has been part of Ohio's execution process since 2009, though was never used. 
 
 McGuire's adult children sobbed a few feet away in a witness room as they watched him die at the state death house in Lucasville in southern Ohio. 
 
 "I'm going to heaven, I'll see you there when you come," McGuire said. He opened and shut his left hand several times before the drugs took effect, appearing to wave to his children. 
 
 McGuire's attorneys argued he would experience "agony and terror" as he struggled to breathe, while state attorneys disputed that scenario. A federal judge sided with the state but acknowledged the new method was an experiment. At the request of McGuire's lawyers, Judge Gregory Frost ordered the state to photograph and then preserve the drugs' packaging boxes and vials and the syringes used in the execution. 
 
 McGuire, 53, was sentenced to death for the 1989 rape and fatal stabbing of Joy Stewart in Preble County in western Ohio. The newly married Stewart was eight months pregnant at the time. 
 
 Stewart's slaying went unsolved for 10 months until McGuire, jailed on an unrelated assault and hoping to improve his legal situation, told investigators he had information about the woman's Feb. 12, 1989, death. His attempts to blame the crime on his brother-in-law quickly unraveled and soon he was accused of being the Joy Stewart's killer, according to prosecutors. 
 
 More than a decade later, DNA evidence confirmed McGuire's guilt, and he acknowledged that he was responsible in a letter to Gov. John Kasich last month. 
 
 "One can scarcely conceive of a sequence of crimes more shocking to the conscience or to moral sensibilities than the senseless kidnapping and rape of a young, pregnant woman followed by her murder," Preble County prosecutors said in a filing with the state parole board last month. 
 
 His attorneys argued McGuire was mentally, physically and sexually abused as a child and has impaired brain function that makes him prone to act impulsively. 
 
 "Dennis was at risk from the moment he was born," the lawyers said in a parole board filing. "The lack of proper nutrition, chaotic home environment, abuse, lack of positive supervision and lack of positive role models all affected Dennis' brain development." 
 
 Documents obtained by The Associated Press show McGuire unsuccessfully sought a reprieve in recent weeks to try to become an organ donor. In November, Kasich granted a death row inmate an eight-month reprieve to let the prison system study his request to donate a kidney to his sister and his heart to his mother. 
 
 Kasich said McGuire couldn't identify a family member who would receive his organs, as required under prison policy. 
 
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 Andrew Welsh-Huggins can be reached on Twitter at https://twitter.com/awhcolumbus ||||| Story highlights Execution was "a failed, agonizing experiment," attorney says 
 
 A medical expert questions why the process took 24 minutes 
 
 Convicted killer Dennis McGuire reportedly says "I'm going to heaven" 
 
 Facing shortages, states are scrambling to find new drug protocols 
 
 Ohio inmate Dennis McGuire appeared to gasp and convulse for roughly 10 minutes before he died Thursday by lethal injection using a new combination of drugs, reporters who witnessed it said. 
 
 McGuire was convicted in 1994 of the rape and murder of 22-year-old Joy Stewart, who was seven months pregnant. Her 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. 
 
 She said McGuire, before the drugs took effect, thanked Stewart's family for a letter he apparently received. 
 
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 "To my children, I'm sorry. I love you. I'm going to heaven and I'll see you there when you come," McGuire reportedly said, according to CNN affiliate WDTN 
 
 Columbus Dispatch reporter Alan Johnson said that the whole execution process took 24 minutes, and that McGuire appeared to be gasping for air for 10 to 13 minutes. 
 
 "He gasped deeply. It was kind of a rattling, guttural sound. There was kind of a snorting through his nose. A couple of times, he definitely appeared to be choking," WDTN quoted Johnson as saying. 
 
 The convicted murderer was pronounced dead at 10:53 a.m. ET. 
 
 The execution 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. 
 
 According to Ohio's corrections department, the state used a combination of the drugs midazolam, a sedative; and the painkiller hydromorphone. 
 
 Both the length of time it took for McGuire to die and his gasping are not typical for an execution, said Howard Nearman, an anesthesiologist at University Hospitals Case Medical Center in Cleveland. 
 
 "Why it took 24 minutes, I really can't tell you," he said. "It just makes you wonder -- what was given? What was the timing, and what were the doses?" 
 
 In an opinion piece written for CNN 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. 
 
 Speaking on behalf of McGuire's legal team, attorney Allen Bohnert called on the governor to impose a moratorium on future executions because of what took place Thursday. 
 
 "At this point, it is entirely premature to consider this execution protocol to be anything other than a failed, agonizing experiment," he said in a statement. 
 
 "The people of the State of Ohio should be appalled at what was done here today in all of our names. Ohio, like its citizens, must follow the law. The state has failed." 
 
 CNN's Sonny Hostin said that McGuire's execution will likely spark debate over whether how inmates react to the use of the drugs constitutes cruel and unusual punishment prohibited by the U.S. Constitution. 
 
 "Whenever there's a change in the lethal injection process clearly it's subject to legal proceedings and perhaps we will see those," Hostin said. 
 
 Ohio ran out of pentobarbital, which is a narcotic and sedative barbiturate, in September, according to JoEllen Smith, 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. 
 
 Stewart's body was discovered by hikers near a creek in southwestern Ohio in February of 1989. Her throat was cut and she had been sodomized. 
 
 There are currently 138 men and one woman on death row in Ohio. 
 
 The state was set to execute death row inmate Ron Phillips using the new drug combination 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. ||||| AP Photo/Ohio Department of Rehabilitation and Correction Undated photo of Dennis McGuire. 
 
 A convicted killer scheduled to be executed Thursday with an untested drug cocktail tried to delay his date with death by offering to become an organ donor after another condemned prisoner won a temporary reprieve with the same request. 
 
 But Ohio Gov. John Kasich turned down two requests from Dennis McGuire because the inmate could not identify a family member that would benefit from his organs, according to documents originally obtained by the Associated Press. 
 
 Kasich earlier granted an eight-month delay to child-murderer Ronald Phillips, who wants to donate a kidney to his mother and his heart to his sister. The state is studying the feasibility. 
 
 Before the governor's reprieve, Phillips, 40, was slated to be the first person in the state executed under a new drug protocol: a combination of the sedative midozolam and the painkiller hydropmorphone. 
 
 But with Phillips awaiting word on possible organ donation, McGuire is now set to become the first to die by the never-tried method, which was adopted after the manufacturer of the primary drug, pentobarbital, stopped selling it to prisons. 
 
 McGuire's lawyers had argued the execution should be scrapped because it could cause a painful and terrifying phenomenon called "air hunger" before death, but a federal judge ruled against them earlier this week. 
 
 McGuire, 53, who was convicted of raping and stabbing to death a pregnant woman in 1989, was moved to Ohio's death house at 10 a.m. on Wednesday and was scheduled to meet with family and friends. 
 
 "Following the visits he will be given his special meal (roast beef, toasted bagel with cream cheese and onion, butter pecan ice cream, fried chicken, potato salad, fried potatoes with onion and Coca-Cola)," according to a statement from the Ohio Department of Rehabilitation and Correction. 
 
 The execution process is slated to begin at 10 a.m. Thursday. ||||| (CNN) -- An Ohio man is set to be put to death Thursday by a two-drug cocktail never before used in a U.S. execution. 
 
 Dennis McGuire was convicted in 1994 of the aggravated murder of Joy Stewart in Preble County, according to the state's governor, who has denied a request for clemency. 
 
 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. 
 
 Ohio ran out of pentobarbital in September, according to JoEllen Smith, 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, a sedative, and hydromorphone, a painkiller, she said. 
 
 Death penalty states scramble for lethal injection drugs 
 
 The combination has never before been used in a U.S. execution. 
 
 "Lawyers for McGuire contend that he will 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," Elisabeth A. Semel, clinic professor of law and director of the Death Penalty Clinic at U.C. Berkeley School of Law, wrote in an opinion piece for CNN this week. 
 
 The state was set to execute Ron Phillips using the two-drug cocktail last year, but Ohio Gov. John Kasich granted the convicted killer a stay of execution pending a review of possible organ donation to his family members. 
 
 Unless there is court action or a reprieve, McGuire will be executed at the Southern Ohio Correctional Facility in Lucasville. 
 
 There are currently 139 men and one woman on death row in Ohio, according to the corrections department website. 
 
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 CNN's Ross Levitt and Deborah Feyerick contributed to this report.
– Dennis McGuire was put to death today with a two-drug combination previously untested in the US, and at more than 15 minutes, it was one of the longest executions in Ohio since the state resumed capital punishment in 1999. McGuire, whose lawyers had attempted to delay his execution by arguing that he would likely feel "terror" following the lethal injection, appeared to gasp a few times as he died, making several loud snorting or snoring sounds, the AP reports. Before his execution, he told his sobbing adult children, "I'm going to heaven, I'll see you there when you come." McGuire had sought a reprieve by offering to become an organ donor, but was rejected because he couldn't identify a family member who would receive his organs, according to documents obtained by the AP. McGuire, who raped and murdered a pregnant woman in 1989, was executed with the untested combination of the sedative midozolam and the painkiller hydropmorphone because of a shortage of the execution drug pentobarbital, NBC reports. His lawyers had contended "that he will suffocate to death in agony and terror. The state disagrees," the director of UC Berkeley's Death Penalty Clinic told CNN before the execution. (One Wyoming state senator, concerned about the shortage of execution drugs, is trying to bring back firing squads as an alternative.)