Convicted killer Dennis McGuire struggled noticeably for his life during a lengthy lethal injection procedure in Ohio on Thursday, and now his family plans to sue the state for violating his Constitutional rights.

A press conference is scheduled for Friday, where the executed man’s children, Amber and Dennis McGuire, and their attorneys will argue the state violated their father’s right to be free of “cruel and unusual punishment.”

In what amounted to an unusually long time for a lethal injection, it took McGuire about 25 minutes to die after being injected with an untested combination of drugs that had never been used before in an execution in the United States.

For about 10 minutes, the controversial cocktail of midazolam and hydromorphone resulted in McGuire “struggling and gasping loudly for air, making snorting and choking sounds that lasted for at least 10 minutes, with his chest heaving and his fist clenched. Deep, rattling sounds emanated from his mouth,” as reported by the Columbus Dispatch.

Soon after McGuire’s death, his attorney Allen Bohnert called the execution “a failed, agonizing experiment by the state of Ohio.”

“The court’s concerns expressed earlier this week have been confirmed,” Bohnert added, according to the Associated Press. “And more importantly, the people of the state of Ohio should be appalled at what was done here today in their names.”

Last week, Bohnert tried to argue that McGuire was at risk of “agony and terror” since the new drug combination could cut off his air supply as he died, but the plea ultimately failed as judges ruled in favor of the state.

The use of midazolam, in particular, has been called into question in the past, as critics believe it leaves inmates aware of their surroundings and in extreme pain as they die.

Dennis McGuire.(AFP Photo / Ohio Department of Rehabilitation and Correction)

“I watched his stomach heave,” said Amber McGuire in a statement, according to the Dispatch. “I watched him try to sit up against the straps on the gurney. I watched him repeatedly clench his fist. It appeared to me he was fighting for his life but suffocating.”

McGuire was originally convicted of raping and killing a pregnant Joy Stewart back in 1994. His pleas for clemency had been denied, and Stewart’s family issued the following statement on the situation surrounding McGuire’s death.

“There has been a lot of controversy regarding the drugs that are to be used in his execution, concern that he might feel terror, that he might suffer. As I recall the events preceding her death, forcing her from the car, attempting to rape her vaginally, sodomizing her, choking her, stabbing her, I know she suffered terror and pain. He is being treated far more humanely than he treated her.”

The behavior of Ohio and other states that condone the death penalty have come under fire since most of the companies that traditionally manufacture the drugs used in lethal injections – generally based in Europe and which are against capital punishment – have halted sales to state correctional departments.

In an effort to replace diminishing supplies of sedatives and paralytics, many states have begun experimenting with alternative drug mixtures, including products typically used to euthanize animals.

As the AP noted, Bohnert has urged Ohio Governor John Kasich to place a moratorium on executions following McGuire’s death. According to the Dispatch, at least one judge, Gregory L. Frost of the U.S. District Court in Cincinnati, cast suspicion on the state’s behavior concerning executions in 2013.

“Ohio has been in a dubious cycle of defending often indefensible conduct, subsequently reforming its protocol when called on that conduct, and then failing to follow through on its own reforms,” he wrote in an unrelated case last year.