Alabama Becomes 1st State to Execute Inmate with Nitrogen Gas, Which Critics Say Is 'Experimental' Method

Kenneth Eugene Smith reportedly writhed and shook violently on the gurney after the gas was administered

•Kenneth Eugene Smith became the first person in the United States to be executed using nitrogen gas

•The Alabama Supreme Court allowed his execution in a November ruling

•The execution was controversial, with Smith's advocates calling the method "experimental"

Alabama carried out the controversial execution of a death row inmate using a method known as nitrogen hypoxia, the firsttime the practice has ever been used in the United States.

Kenneth Eugene Smith, who has been on death row since 1990, was executed Thursday night, according to reports from CNN, CBS News and NPR.

The execution began at 7:53 p.m. and Smith was pronounced dead at 8:25. Officials said nitrogen flowed for 15 minutes and that a nitrogen mask was kept on Smith for five minutes after he flatlined, the outlets reported.

NPR and the Associated Press reported that Smith writhed and shook violently for about two minutes on the gurney, before five minutes of heavy breathing, citing media witnesses.

Related: Alabama Can Become First State to Execute Inmate with Nitrogen Gas, State's Supreme Court Rules

"Tonight Alabama caused humanity to take a step backward,” Smith reportedly said in his last words, per the outlets. “I'm leaving with love, peace and light. Thank you for supporting me. Love all of you.”

Alabama, Oklahoma and Mississippi are the only states that have authorized nitrogen hypoxia for executions, the Associated Press reported. Alabama became the first to actually utilize the procedure, which involves forcing pure nitrogen into the inmate's lungs while cutting off the oxygen supply, according to the AP.

Smith’s legal team fought the new method of execution, calling it “experimental, never-before-used method” in a joint statement previously reported by AL.com.

The execution was set after the Alabama Supreme Court voted 6 to 2 in November to grant state Attorney General Steve Marshall’s execution warrant. On Thursday the United States Supreme Court declined to stop Smith’s execution, despite three dissenting justices.

“With deep sadness, but commitment to the Eighth Amendment’s protection against cruel and unusual punishment, I respectfully dissent,” Justice Sonia Sotomayor wrote in her dissent.

Alabama officials have claimed nitrogen hypoxia is, "the most painless and humane method of execution known to man,” according to NPR’s reporting, though the American Veterinary Medical Association called the method “unacceptable” for all mammals except pigs.

CBS reported a joint statement from Smith and his spiritual advisor Rev. Jeff Hood, sent out the afternoon of the execution, criticizing the use of nitrogen hypoxia.

"Our prayer is that people will not turn their heads. We simply cannot normalize the suffocation of each other," the statement reportedly said.

Smith was convicted of the 1988 murder of Elizabeth Dorlene Sennett, the wife of local minister Charles Sennett, who was having an affair and was in debt, according to a 2000 decision affirming Smith’s conviction and “electrocution” filed to the Court of Criminal Appeals of Alabama, reviewed by PEOPLE.

After taking out an insurance policy on his wife, Sennett hired a group of men, including Smith, to kill Elizabeth and to make it look like a burglary gone wrong, according to a confession included in the decision. She was killed after being stabbed multiple times.

Sennett died by suicide a week after her death, while Smith’s accomplice was executed for the crime in 2010.

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Controversially, Smith’s death sentence was handed down by a judge who overruled a jury, who voted 11 to 1 to sentence him to life in prison.

Smith already survived a previous execution attempt in 2022, reported AL.com. He was reportedly strapped to a gurney, set to die from lethal injection, when the execution was halted because workers did not think they could carry out the process before the death warrant expired at midnight.

Elizabeth Sennett’s son, Mike, released a statement reported by CBS following the execution Thursday.

"It's kind of a bittersweet day. We're not going to be jumping around," he reportedly said. "But we're glad this day is over."

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