Jessie Hoffman Jr, 46, was pronounced dead at 6.50pm (10.50am AEDT) at the Louisiana State Penitentiary, authorities said, adding the nitrogen gas had flowed for 19 minutes during what one official characterised as a “flawless” execution.

It was the state’s first execution in 15 years.

Hoffman was convicted of killing a 28-year-old advertising executive, Mary “Molly” Elliott, in New Orleans, a crime committed when he was 18.

Nitrogen gas had previously been used just four times to execute a person in the US – all in Alabama. Three other executions, by lethal injection, are scheduled this week –in Arizona on Wednesday and in Florida and Oklahoma on Thursday.

After court battles earlier this month, attorneys for Hoffman had turned to the Supreme Court in last-ditch hopes of halting the execution. Last year, the court declined to intervene in the nation’s first nitrogen hypoxia execution, in Alabama.

Hoffman’s lawyers had argued that the nitrogen gas method violated the Eighth Amendment’s prohibition on cruel and unusual punishment. They also said it infringed on Hoffman’s freedom to practice religion, specifically his Buddhist breathing and meditation in the moments leading up to death.

However, Louisiana officials maintained the method, which deprives a person of oxygen, is painless. They also said it was past time for the state to deliver justice as promised to victims’ families after a decade and a half hiatus – one brought on partly by an inability to secure lethal injection drugs.

The Supreme Court voted 5-4 in declining to step in.

Attorney General Liz Murrill said she expects at least four people on Louisiana’s death row to be executed this year and said “justice will finally be served” by executing Hoffman.

This week, Hoffman’s attorneys filed several challenges in state and federal courts seeking to spare him.

At a hearing Tuesday morning, 19th Judicial District Court Judge Richard “Chip” Moore also declined to stop the execution. He agreed with state lawyers who argued the man’s religion-based arguments fell under the jurisdiction of a federal judge who had already ruled on them, according to local news outlets.

Under Louisiana protocol, which is nearly identical to Alabama’s, Hoffman is to be strapped to a gurney and have a full-face respirator mask fitted tightly on him. Pure nitrogen gas is then to be pumped into the mask, forcing him to breathe it in and depriving him of the oxygen needed to maintain bodily functions.

The gas is to be administered for at least 15 minutes or five minutes after his heart rate reaches a flatline indication on the EKG, whichever is longer.

Each inmate put to death using nitrogen in Alabama has appeared to shake and gasp to varying degrees during their executions, according to media witnesses, including an Associated Press reporter. The reactions are involuntary movements associated with oxygen deprivation, state officials have said.

Alabama first used the lethal gas to put Kenneth Eugene Smith to death last year, marking the first time a new method had been used in the US since lethal injection was introduced in 1982.

Four states – Alabama, Louisiana, Mississippi and Oklahoma – specifically authorise execution by nitrogen hypoxia, according to records compiled by the Death Penalty Information Centre.

Then on Tuesday, Arkansas Governor Sarah Huckabee Sanders signed legislation allowing executions using nitrogen gas, making hers the fifth state to adopt the method. Arkansas currently has 25 people on death row.

Seeking to resume executions, Louisiana’s GOP-dominated legislature expanded the state’s approved death penalty methods last year to include nitrogen hypoxia and electrocution. Lethal injection was already in place.

Over recent decades, the number of executions nationally has declined sharply amid legal battles, a shortage of lethal injection drugs and waning public support for capital punishment. That has led a majority of states to either abolish or pause carrying out the death penalty.

On Tuesday afternoon, a small group of execution opponents held a vigil outside the rural southeast Louisiana prison at Angola, where the state’s executions are carried out. Some passed out prayer cards with photos of a smiling Hoffman and planned a Buddhist reading and “Meditation for Peace.”