One of the nation’s leading anesthesiologists says in a new court filing that he has concluded “to a reasonable degree of medical certainty” that Billy Ray Irick experienced “torturous” pain when he was executed last month.

Based on the accounts of media witnesses (including this Scene reporter), Dr. David Lubarsky asserts that Irick was “aware and sensate during his execution and would have experienced the feeling of choking, drowning in his own fluids, suffocating, being buried alive, and the burning sensation caused by the injection of the potassium chloride.”

The state put Irick to death on Aug. 9 for the 1985 rape and murder of 7-year-old Paula Dyer in Knox County. It was the state’s first execution since 2009, as well as its first using a controversial new lethal injection protocol — the same protocol the state intends to use to execute Edmund Zagorski on Oct. 11.

The three-drug cocktail — consisting of midazolam, vecuronium bromide and potassium chloride, which are all injected one at a time — prompted a lawsuit from more than 30 death row inmates, including Irick, who argued it would amount to torture. Lubarsky, a Florida doctor who has researched lethal injection, testified as an expert witness during the trial over the lethal drugs earlier this year. He told the court there was no doubt that midazolam, a sedative, would not prevent Irick from feeling immense pain during his execution. A Nashville judge upheld the protocol in July.

The death row prisoners appealed, but Gov. Bill Haslam, the Tennessee Supreme Court and the Supreme Court of the United States all denied Irick’s requests for a stay of execution. Still, in a blistering dissent, U.S. Supreme Court Justice Sonia Sotomayor argued that Irick was certain to experience excruciating pain.

"In refusing to grant Irick a stay, the Court today turns a blind eye to a proven likelihood that the State of Tennessee is on the verge of inflicting several minutes of torturous pain on an inmate in its custody, while shrouding his suffering behind a veneer of paralysis," she wrote.

In conclusion, Sotomayor added: "If the law permits this execution to go forward in spite of the horrific final minutes that Irick may well experience, then we have stopped being a civilized nation and accepted barbarism. I dissent."

In the new filing, Lubarsky says the physical behavior described by witnesses to Irick's execution — choking, moving his head and straining his forearms against the restraints — were "signs that Mr. Irick was not in a plane of surgical anesthesia during his execution.”

“This is important because an inmate who is not placed in a plane of surgical anesthesia is not protected from the subsequent torturous effects of the lethal injection process,” Lubarsky says.

Lubarsky also highlights the fact that Irick's hands were taped to the gurney.

“A trained observer knows that if a patient moves his fingers or hands, that is a clear indicator that they are not anesthetized,” he says.

"The taping of Mr. Irick’s hands affirmatively prevented the Warden from observing an important indicator that Mr. Irick was not anesthetized," Lubarsky later adds. "The taping of an inmate’s hands is not necessary, because the inmate’s wrists are restrained, which is more than sufficient to prevent the inmate from pulling out the catheter."

A Nashville judge blocked an autopsy from being performed on Irick's body, citing Irick's expressed religious beliefs.

In a new legal challenge filed last month, death row prisoners argue that Irick had been tortured to death and state that they would rather be executed by firing squad.