Dennis McGuire, a prisoner in Ohio sentenced to death for the rape and murder of Joy Stewart in 1989, took more than 20 minutes to die on Thursday after being given a lethal injection. According to the Associated Press, the combination of drugs used to kill McGuire had never before been used in the United States for execution purposes.

McGuire reportedly made "loud snorting noises," before 10 minutes of "irregular breathing and gasping." Lethal injections in the United States are usually carried out using pentobarbital, a method that leads to much shorter executions, but Ohio's supplies of the drug have run out after its Danish manufacturers blocked its export for use in executions in 2011. In October, officials made the decision to use a different cocktail of drugs — consisting of a sedative and a painkiller — that had not been tested on humans in the US.

McGuire was accused of raping and murdering the pregnant Joy Stewart after being jailed for an unrelated assault, having initially told police his brother-in-law committed the murder in an effort to reduce his punishment. DNA evidence confirmed his guilt more than 10 years later, and last month McGuire took responsibility for his crimes in a letter to Ohio governor John Kasich.

His lawyers — who argued during his trial that McGuire was abused as a child and had diminished brain function — last week claimed that the new drugs could cause their client "agony and terror" as he died. McGuire's attorney, Allen Bohnert, called the execution a "failed, agonizing experiment." The McGuire family plans to sue the state of Ohio for the way Dennis was executed, but assistant attorney general Thomas Madden said that while the constitution bans cruel and unusual punishment, "you're not entitled to a pain-free execution."