The state used intravenous doses of two drugs, the sedative midazolam and the painkiller hydromorphone, to put McGuire to death for the 1989 rape and fatal stabbing of a pregnant woman, Joy Stewart. The method was adopted after supplies of a previously used execution drug dried up because the manufacturer put it off limits for capital punishment.
Executions with the former method were typically much shorter and did not include the types sounds McGuire uttered.
A few minutes before McGuire was put to death, state prison director Gary Mohr said he was confident the execution would be carried out in a humane and dignified manner. As is common practice, prison officials did not immediately comment after the execution except to release the time of death.
Strapped to a gurney in the execution chamber, McGuire thanked Stewart's family for their "kind words" in a letter he apparently received from them.
"I'm going to heaven, I'll see you there when you come," he said through a microphone held by the warden.
As his adult children sobbed a few feet away in a witness room, McGuire opened and shut his left hand as if waving to his daughter, son and daughter-in-law.
More than a minute later he raised himself up, looked in the direction of his family and said, "I love you. I love you" — his words audible even though the microphone had been removed.
McGuire was still for almost five minutes, then emitted a loud snort, as if snoring, and continued to make that sound over the next several minutes. He also soundlessly opened and shut his mouth several times as his stomach rose and fell.
"Oh my God," his daughter, Amber McGuire, said as she observed her father's final moments.
A coughing sound was Dennis McGuire's last apparent movement, at 10:43 a.m. He was pronounced dead 10 minutes later.
Attorneys for the state called McGuire's bid to halt his execution with the untried method an "eleventh hour" appeal based on claims that should have been raised years ago, because the process had been in place as a backup method.
And although the U.S. Constitution bans executions that constitute cruel and unusual punishment, that doesn't mean procedures are entirely comfortable, the state argued.
"You're not entitled to a pain-free execution," Assistant Attorney General Thomas Madden told federal Judge Gregory Frost.
Frost sided with the state but acknowledged the new method was an experiment. At the request of McGuire's lawyers, he ordered the state to photograph and then preserve the drugs' packaging boxes and vials and the syringes used in the execution.