How nitrogen gas executions work as death row mate chooses method before chilling final act

As one of the longest-serving death row inmates was executed via nitrogen gas, we take a look at how the method actually works.

On Tuesday (June 10), murderer Gregory Hunt took his final breaths after more than three decades behind bars.

The 65-year-old brutally beat 32-year-old Karen Lane to death after sexually assaulting her in Cordova, Alabama, in 1988.

He was convicted and sentenced to death row in 1990, after being found guilty of capital murder committed during a sexual assault and burglary.

Hunt had been dating Lane for about a month, allegedly breaking into her apartment and attacking her out of jealousy.

Lane had sustained 60 injuries during the horrific attack.

Hunt was declared dead on Tuesday at 6:26pm after breathing in nitrogen gas.

Before the procedure took place, he was asked whether he had any final words, to which he replied 'no' before giving a chilling signal to witnesses in the auditorium.

He was then strapped to a gurney with a mask covering his entire face as the nitrogen gas was administered shortly before 6pm.

At 5:59pm, he moaned as the execution was taking place, with his feet rising, before taking four more deep breaths as he gasped for air - with long pauses in between (via NBC News).

There was no sign of movement after 6:05pm.

There are only three US states which approve the use of nitrogen gas for death row inmates: Alabama, Oklahoma and Mississippi.

How does nitrogen gas execution work?

Inmates breath in pure nitrogen gas via a mask placed over their face, causing the oxygen levels in their bloodstream drop.

This leads to hypoxia - where the body is deprived of an adequate oxygen supply at the tissue level.

According to the Cleveland Clinic, hypoxia causes a slow heart rate, extreme restlessness and a blue tinge to the skin.

Inmates can then become unconscious within a matter of minutes as the brain cells begin dying off.

Some death row inmates can choose to be executed via nitrogen gas (Mbz-photodesign/Getty Images)

Brain damage usually begins within four minutes of lack of oxygen, Cleveland Clinic adds.

If uninterrupted, it results in death not too much sooner.

According to Alabama Department of Corrections’ exe­cu­tion pro­to­col, nitro­gen ​is 'admin­is­tered for 15 min­utes or five min­utes fol­low­ing a flat­line indi­ca­tion on the EKG, whichev­er is longer'.

While some claim that hypoxia is a painless and humane method, eyewitness accounts from previous executions suggest otherwise, making it quite a controversial method.

For example, during Alabama's first nitrogen hypoxia execution of Kenneth Eugene Smith in January 2024, onlookers reported that Smith appeared conscious for several minutes, exhibiting convulsions and labored breathing before becoming unresponsive.

Similar reactions were noted in subsequent executions - including Hunt's.