Nitrogen asphyxia is torturous

Back on 25 January 2024, death penalty demonstrators once more gathered outside a USA prison. This time though, things were a bit different - for two reasons: the intended execution agent was a gas and the condemned man was a repeat attender.

Who and why?

Kenneth Smith was one of two assassins-for-hire who in 1988 killed Elizabeth Sennett, the wife of a pastor who hoped her life insurance could ease his financial troubles. Shortly after the killing though, the pastor killed himself - rather than face earthly justice.

A long 22 years later, in 2010, Kenneth’s partner-in-crime received the stiffest penalty meted out by the US Justice System - execution. And then finally, a whopping 35 years after his crime, Kenneth himself was finally executed whilst simultaneously making history as the first person in the USA to be subjected to nitrogen asphyxiation.

Why wait, why gas?

Why did the authorities use nitrogen gas rather than lethal injection or another method, and why did they waited 35 years to execute him? Well the answers to these two questions are linked.

The USA’s capital punishment appeal system is notoriously slow and convoluted. It’s common for condemned people to spend around 20 years on death row. Some argue that this long wait for almost certain death is itself a form of psychological torture. And it’s not uncommon for death row prisoners to die of illness rather than by the executioner’s hand.

In Kenneth’s case, it was 33 years between conviction and the authorities first taking him to the death chamber in November 2022. But things didn’t go to plan.

As is common to many botched executions, his would-be executioners lacked sufficient skill in venous access to get the necessary needles into him. After several hours of trying, his death warrant expired and so they had to abandon the execution and return him to death row, his home for the previous three decades.

And in the aftermath of that debacle the authorities promised not to try to use lethal injection on him in the future.

So that is why Kenneth died at another time and in another way.

Who worried?

There were many concerns in the run up to nitrogen’s debut in the death chamber. This was due to at least two key factors.

Firstly, no-one can reasonably deny that surviving a botched execution is a traumatising experience. Kenneth’s legal team argued, ultimately unsuccessfully, that it would be cruel to do this to him all over again.

And there were concerns about the use of nitrogen in itself. Even the UN High Commissioner for Human Rights was alarmed:-

We have serious concerns that Smith’s execution in these circumstances could breach the prohibition on torture or other cruel, inhuman, or degrading treatment or punishment, as well as his right to effective remedies. These are rights set out in two International Human Rights treaties where the United States is bound by – the Covenant on Civil and Political Rights and the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment [CAT].

What actually happened?

Kenneth made history back in January 2024. What did an official eye witness observe?

Marshall, the attorney general, gave prison officials the OK to begin the execution at 7:56 p.m… Smith began to shake and writhe violently, in thrashing spasms and seizure-like movements, at about 7:58 p.m. The force of his movements caused the gurney to visibly move at least once. Smith’s arms pulled against the straps holding him to the gurney. He lifted his head off the gurney and then fell back. The shaking went on for at least two minutes. Hood repeatedly made the sign of the cross toward Smith. Smith’s wife, who was watching, cried out. Smith began to take a series of deep gasping breaths, his chest rising noticeably. His breathing was no longer visible at about 8:08 p.m. The corrections officer who had checked the mask before walked over to Smith and looked at him.
PBS News

What’s happened since?

Since then seven other people - two more in 2024 and five to date in 2025 - have gone the same way. How have they gone? Let’s look at first of 2025, and the most recent one.

The fourth man to die by nitrogen was Demetrius Frazier. Having been convicted for the 1991 rape and killing of Pauline Brown, he’d spent 29 years on death row before being the first person of 2025 to be executed by nitrogen asphyxia, on 6 February 2025:

Frazier was strapped to a gurney with a blue-rimmed gas mask covering his entire face. The execution began at about 6:10 p.m. after a corrections officer did a final check of the mask.

Frazier moved his outstretched palms in a swirling circular movement for the first minute or two. At 6:12 p.m., he stopped circling his hands. He appeared to grimace, quiver on the gurney and take a gasping breath. A minute later, he raised both legs several inches off the gurney and then lowered them.

His breathing slowed at 6:14 p.m. to a series of sporadic breaths. He had no visible movement by about 6:21 p.m. The curtains to the execution chamber closed at 6:29 p.m.

Alabama Corrections Commissioner John Hamm said afterward that the gas flowed for about 18 minutes and that instruments indicated Frazier no longer had a heartbeat 13 minutes after the gas began.
AP News

And moving onto the most recent execution, that of Anthony Todd Boyd on 23 October 2025. Having been convicted for the 1993 kid­nap­ping and mur­der of Gregory ​“New York” Hugule, he’d spent 30 years on death row. His nitrogen death was the longest so far, taking almost 40 minutes. And it was documented in detail by a journalist who had also seen several of the earlier nitrogen executions:

At 5:50pm, cor­rec­tion­al offi­cers opened the cur­tains to the exe­cu­tion cham­ber, and Mr. Boyd spoke his last words.

“I didn’t kill any­body. I didn’t par­tic­i­pate in killing any­body,” he said. ​“There is no
jus­tice in this state. It’s all polit­i­cal. It’s revenge moti­vat­ed. It’s not about clo­sure, because clo­sure comes from with­in, not with an exe­cu­tion. There will be no jus­tice in this state until we change this sys­tem. I want all my peo­ple to keep fight­ing. Let’s get it.”

At 5:55, a prison offi­cial checked the gas mask attached to Mr. Boyd’s face and his
spir­i­tu­al advi­sor began to read aloud from his Bible. Two min­utes lat­er, at 5:57, media wit­ness­es report­ed that Mr. Boyd began to ​“vio­lent­ly react, thrash­ing against his restraints.” According to [the journalist] Mr. Hedgepeth, Mr. Boyd’s eyes rolled back, and he con­tin­ued to con­vulse, lift­ing his legs from the gur­ney. By 6:00, Mr. Boyd’s move­ment stead­ied, but he ​“began a series of deep, ago­nized breaths that last­ed for more than 15 min­utes, each break shud­der­ing Boyd’s restrained head and neck.” According to Mr. Hedgepeth’s account, Mr. Boyd gasped more than 225 times. At 6:16 Mr. Boyd was still draw­ing deep breaths… Prison offi­cials announced Mr. Boyd’s time of death at 6:33pm.
Death Penalty Information Center

What’s the verdict?

So, it turns out that nitrogen is not the humane killer touted by proponents of the death penalty. Quite the opposite.

As one of three dissenting judges when the U.S. Supreme Court Justice turned down Anthony Boyd’s last minute appeal for a stay of execution, Justice Sonia Sotomayor put it as only a judge can:

“Boyd asks for the barest form of mer­cy: to die by fir­ing squad, which would kill him in sec­onds, rather than by tor­tur­ous suf­fo­ca­tion last­ing up to four min­utes. The Constitution would grant him that grace. My col­leagues do not. The Court thus turns its back on Boyd and on the Eighth Amendment’s guar­an­tee against cru­el and unusual punishment.”
Justice Sonia Sotomayor [emphasis added in bold]

In the modern history of capital punishment, electrocution has proven barbaric. Lethal injection is tricky if you’re not terribly handy with a cannula and have inside deals with pharmaceutical companies. Firing squads are out of fashion for various other reasons. And now nitrogen isn’t working out so well either.

Justice Sotomayor’s dissent is worth reading in full. May her wisdom help us step up the argument against the continued use of nitrogen in the state-sanctioned killing of people who, guilty or not, are human and so - like the rest of us - worthy of humane treatment.

Dr Rachael Pickering is our chief medical officer. Her views do not necessarily represent those of Integritas Healthcare. First published on 25 January 2024 in the run-up to the execution of Kenneth Smith, this article was edited and republished on 8 November 2025.

The Lord looked down… from heaven He viewed the earth, to hear the groans of the prisoners and release those condemned to death.
Psalm 102:18-20