The UN human rights chief has expressed deep regret over the execution of a prisoner in the United States on Thursday night through the country’s first-ever use of nitrogen asphyxiation as a method of implementing the death penalty.

“I deeply regret the execution of Kenneth Eugene Smith in Alabama despite serious concerns that this novel and untested method of suffocation may amount to torture, cruel, inhuman or degrading treatment,” said Volker Türk, the UN High Commissioner for Human Rights, OHCHR.

Convicted of murder in 1988, Smith, 58, had been sentenced to death in the state of Alabama. An attempt to carry out the execution in 2022, failed.

Last week, the Human Rights Council had called for Alabama to halt Smith’s execution and to refrain from taking steps towards any other executions using nitrogen asphyxiation.

On Thursday evening, nitrogen hypoxia gas was administered to Smith.

It took 22 minutes before he was formally declared dead, media reports said.

According to media and other witnesses in the execution chamber, the prisoner shook violently, writhing and convulsing on the gurney.

Prior to the execution, authorities in Alabama reportedly described the use of pure nitrogen gas as “perhaps the most humane method of execution ever devised”.

“The death penalty is inconsistent with the fundamental right to life,” said OHCHR Spokesperson Ravina Shamdasani on Friday morning in a post on X, formerly Twitter.

“We urge all States to put in place a moratorium on its use as a step towards universal abolition.”

Alabama execution

The US state of Alabama has executed Kenneth Eugene Smith, a convicted murderer, with nitrogen gas, an episode marking the first time use of the method globally.

Smith, 58, lost two final appeals to the Supreme Court and one to a federal appeals court, arguing the execution was a cruel and unusual punishment, reported BBC.

Alabama tried and failed to execute the convict by lethal injection in 2022.

He was sentenced to death for his role in a 1988 murder for hire.

Smith was left with PTSD

According to Death Penalty Information Center website,  Smith’s case is unusual in several respects.

“First, he has already survived one execution attempt, which left him with post-traumatic stress disorder, according to a clinical psychologist and trauma expert who examined him. On November 17, 2022, the state tried and failed to execute Mr. Smith using lethal injection but abandoned its efforts after four hours when staff were unable to access a vein,” the website said.

A journalist who witnessed the execution described to the BBC how he thrashed violently on the gurney, and said the process took around 25 minutes in total.

One of the five members of the media transported to Holman Correctional Facility in Atmore to witness the execution told the BBC it was unlike any other he’d witnessed in Alabama.

“I’ve been to four previous executions and I’ve never seen a condemned inmate thrash in the way that Kenneth Smith reacted to the nitrogen gas,” Lee Hedgepeth told the BBC.

“Kenny just began to gasp for air repeatedly and the execution took about 25 minutes total.”

Alabama Attorney General Steve Marshall reacted to the development and said in a statement: “Justice has been served. Tonight, Kenneth Smith was put to death for the heinous act he committed over 35 years ago: the murder-for-hire slaying of Elizabeth Sennett, an innocent woman who was by all accounts a godly wife, a loving mother and grandmother, and a beloved pillar of her community.”