Kenneth Eugene Smith’s last words before execution using nitrogen hypoxia method

A convicted murderer put to death via an untested method, used his last words to slam the execution as forcing humanity backwards.

Elizabeth Sennett (right) who was killed by Kenneth Smith.

A convicted killer in the US has been executed using an untested method, sparing his last words to slam authorities for causing “humanity to take a step backwards”.

Kenneth Eugene Smith was put to death in the state of Alabama on Thursday US time, more than 35 years after being paid $1000 to murder Elizabeth Sennett.

Smith was executed using nitrogen hypoxia, a technique previously unused in the country, which involved an airtight mask being fitted to his face and pure nitrogen used to suffocate him.

Before the execution, authorities said he would be unconscious in mere seconds and dead in minutes.

News outlet AL.com reported Smith’s last words to his supports before the gas begun to flow included that he was “leaving in love, peace and light”.

“Tonight Alabama causes humanity to take a step backwards … Thank you for supporting me,” he said.

“Love all of you.”

Elizabeth Sennett (right) who was killed by Kenneth Smith.

Witnesses reported the murderer was “writhing and thrashing” as the gas took effect and around five minutes of heavy breathing, according to the publication.

Smith was hired to kill Ms Sennett in 1988 by her adulterous pastor husband, Charles Sennett, who subsequently took his own life.

Ms Sennett was stabbed and beaten to death using a fire extinguisher.

After previously surviving an lethal injection in 2022, when officials could not insert an intravenous line into his arm, authorities settled on a new method of execution by nitrogen hypoxia.

Smith launched a last-ditch appeal in the US Supreme Court to stay the death sentence but lost the case this week.

The court gave authorities in Alabama 30 hours to carry out the sentence.

Kenneth Eugene Smith was killed using nitrogen gas, a novel method that the UN has likened to "torture”. Picture: Alabama Department of Corrections/AFP

In a statement before the execution, Smith and his spiritual adviser Reverend Jeff Hood slammed the chosen method.

“The eyes of the world are on this impending moral apocalypse. Our prayer is that people will not turn their heads,” the statement read.

“We simply cannot normalise the suffocation of each other.”

Alabama Governor Kay Ivey confirmed the execution in a statement, saying the method was lawful and had been “previously requested” by Smith as an alternative to lethal injection.

“On March 18, 1988, 45-year-old Elizabeth Sennett’s life was brutally taken from her by Kenneth Eugene Smith,” Mr Ivey said.

Elizabeth Sennett was stabbed and bashed to death.

“After more than 30 years and attempt after attempt to game the system, Mr Smith has answered for his horrendous crimes.

“The execution was lawfully carried out by nitrogen hypoxia, the method previously requested by Mr Smith as an alternative to lethal injection.

“At long last, Mr Smith got what he asked for, and this case can finally be put to rest.”

Abraham Bonowitz, executive director of Death Penalty Action, disagreed.

A previous attempt to execute Smith via lethal injection was abandoned in 2022. Picture: Paul Buck/AFP

Mr Bonowitz said before the execution that the governor was to be “party to a torturous violation of human rights”.

“If Kenny Smith were on trial today, he could not be sentenced to death at all because his jury was not unanimous regarding his sentence, and jury overrides were outlawed in Alabama in 2017,” he said.

In the last four decades, the peak of US executions were in 1999 when 98 prisoners were put to death.

In 2023, a little more than 20 people were executed.