A prisoner has been executed in the US state of Alabama by lethal injection over a 1996 murder.

The move came after a divided US supreme court sided with the state and rejected defence claims the man had an intellectual disability that cost him a chance to choose a less “torturous”, though untried, method of execution.

Matthew Reeves, 43, was put to death at Holman Prison after the court lifted a lower court order that had prevented corrections workers from executing the prisoner.

Reeves was convicted of killing Willie Johnson Jr, a driver who gave him a lift in 1996.

Evidence showed Reeves went to a party afterwards and celebrated the killing.

The inmate had no last words. After craning his neck to look around a few times, Reeves grimaced and looked at his left arm towards an intravenous line.

With his eyes closed and mouth slightly agape, Reeves’ abdomen moved repeatedly before he grew still.

Alabama governor Kay Ivey said Mr Johnson was “a good Samaritan lending a helping hand” who was brutally murdered. She added that Reeves’ death sentence was fair, “and tonight, justice was rightfully served”.

Prison officials said some of Mr Johnson’s family witnessed the execution. In a written statement, they said: “After 26 years justice (has) finally been served. Our family can now have some closure.”

Reeves was convicted of capital murder for killing Mr Johnson with a shotgun blast to the neck during a robbery in Selma on November 27 1996.

He was killed after picking up Reeves and others on the side of a rural highway.

After the dying man was robbed of 360 dollars, Reeves, then 18, went to a party where he danced and mimicked Mr Johnson’s death convulsions, authorities said.

A witness said Reeves’ hands were still stained with blood at the celebration.

While courts have upheld Reeves’ conviction, a last-minute fight by his lawyers seeking to stop the execution focused on his intellect, his rights under federal disability law and how the state planned to kill him.

The US supreme court rejected a decision by the 11th US circuit court of appeals, which had ruled that a district judge did not abuse his discretion in ruling that the state could not execute Reeves by any method other than nitrogen hypoxia, which has never been used.

Holman Prison
Holman Prison in Atmore, Alabama (AP)

Reeves’ lawyers criticised the US supreme court’s failure to explain its decision to let the execution proceed.

“The immense authority of the supreme court should be used to protect its citizens, not to strip them of their rights without explanation,” they said.

In 2018, Alabama death row inmates had a chance to sign a form choosing either lethal injection or nitrogen hypoxia as an execution method after legislators approved the use of nitrogen.

But Reeves was among the inmates who did not fill out the form stating a preference.

Suing under the American With Disabilities Act, Reeves claimed he had intellectual disabilities that prevented him from understanding the form offering him the chance to choose nitrogen hypoxia – a method never used in the US – over lethal injection, which the inmate’s lawyers called “torturous”.

Reeves also claimed the state failed to help him understand the form. But the state argued he was not so disabled that he could not understand the choice.

Alabama switched from the electric chair to lethal injection after 2002, and in 2018 legislators approved the use of another method, nitrogen hypoxia, amid defence challenges to injections and shortages of chemicals needed for the procedure.

The new method would cause death by replacing oxygen that the inmate breathes with nitrogen.

Lawyers argued that Reeves was a poor reader and intellectually disabled, meaning he was not capable of making such a decision without assistance that should have been provided under the American With Disabilities Act.

A prison worker who gave Reeves a form did not offer aid to help him understand, they said.

With Reeves contending he would have chosen nitrogen hypoxia over a “torturous” lethal injection had he comprehended the form, the defence filed suit asking a court to halt the lethal injection.

US district judge R Austin Huffaker, Jr blocked execution plans, ruling that Reeves had a good chance of winning the claim under the disabilities law.

A defence expert concluded Reeves had a first grade reading level and the language competency of someone as young as four, but the state disagreed that Reeves had a disability that would prevent him from understanding his options.

An Alabama inmate who was put to death by lethal injection last year, Willie B Smith, had unsuccessfully raised claims about being intellectually unable to make the choice for nitrogen hypoxia.