US executes first death row inmate with nitrogen gas

Hitman Kenneth Eugene Smith became the first person to be put to death using pure nitrogen gas - a punishment he argued it was a 'cruel' and 'unusual' as Ian Woods reports


A man who was paid $1,000 (£788) to kill an Alabama woman more than 30 years ago was executed with pure nitrogen gas - the first execution of its kind in the world.

Convicted murderer Kenneth Smith, 58, appeared to convulse and shake after breathing in the gas.

Smith had lost two final appeals to prevent the execution. On Thursday, the US Supreme Court denied a last-minute appeal from Smith's attorneys who argued it was an unusual and cruel punishment.

Alabama had tried and failed to execute Smith in 2022 by using lethal injection.

Smith inhaled pure nitrogen gas through a face mask causing oxygen deprivation. He appeared conscious for several minutes into the procedure.

For at least two minutes, Smith made seizure-like movements on the gurney that sometimes had him pulling against the restraints.

That was followed by several minutes of laboured breathing. He was pronounced dead after 22 minutes.

Inside the chamber with him was his spiritual adviser, Revered Jeff Hood who earlier on Thursday said Smith ate a final meal of T-bone steak, hash browns, toast, and eggs slathered in A1 steak sauce.

Alabama's lethal injection chamber at Holman Correctional Facility, in Atmore, pictured in 2002. Credit: AP

“He’s terrified at the torture that could come. But he’s also at peace. One of the things he told me is he is finally getting out,” he added.

The method of execution has been described by the Alabama attorney general's office as the "most painless and humane method of execution known to man", but the United Nations (UN) has disputed this, saying nitrogen hypoxia could "amount to torture" and break international human rights laws.

The American Veterinary Medical Association in 2020 euthanasia guidelines wrote nitrogen hypoxia is not an acceptable euthanasia method for most mammals because the anoxic environment is "distressing".

On Wednesday, both the US Supreme Court and 11th Circuit Court of Appeals said they would not block the execution despite Smiths' pleas for it to intervene.

"What effect the condemned person will feel from the nitrogen gas itself, no one knows," Dr. Jeffrey Keller, president of the American College of Correctional Physicians said.

Alabama, along with Mississippi and Oklahoma, is the only US states to have authorised the use of nitrogen hypoxia.

The death penalty is a legal punishment that can be given out in 27 of the US states, and 24 people died as a result of capital punishment in 2023, as recorded by the Death Penalty Information Centre.

What was Smith convicted of?

Smith was one of two men convicted for murdering a woman in 1988.

The incident was a "murder-for-hire", with Smith and another man, John Forrest Parker, each receiving $1,000 (£786) to kill Elizabeth Sennett on behalf of her husband.

Mike Sennett, son of Elizabeth Sennett, and other family members speak after Kenneth Eugene Smith’s execution. Credit: AP

Her husband killed himself when he became a suspect. John Forrest Parker, the other man convicted, was executed in 2010.

The victim's son, Charles Sennett Jr, said in an interview with WAAY-TV that Smith "has to pay for what he's done".

He and other family members plan to witness the execution.

"And some of these people out there say, 'Well, he doesn't need to suffer like that'. Well, he didn't ask Mama how to suffer?" Mr Sennett Jr said.

"They just did it. They stabbed her - multiple times."


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How did the execution work?

The method is known as Nitrogen Hypoxia.

Brain cells begin to die after one minute without oxygen, and serious brain damage is "likely" after three minutes, according to University of Michigan research.

After 15 minutes without oxygen brain recovery is "virtually impossible".

Officials strapped Smith into a gurney and then placed a facepiece, similar to those typically used to supply oxygen, onto his face.

A warden read a death warrant and asked Smith if he has any last words, before activating the "nitrogen hypoxia system" from another room.

The nitrogen gas was expected to be administered for at least 15 minutes or “five minutes following a flatline indication on the EKG, whichever is longer,” according to the state protocol.

Smith's attorneys had said the mask in question was not air tight and so oxygen could seep through, making the execution process longer and possibly leaving him in a vegetative state rather than killing him.

A doctor testified on behalf of Smith that the low-oxygen environment could cause nausea, leaving him to choke to death on his own vomit.


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