WARNING: Disturbing content.

THE American state where a death-row inmate endured an agonising 43-minute-long botched execution is surging ahead with plans to kill more prisoners. But there's a catch.

Oklahoma, where Clayton Lockett blew a vein while strapped to his death bed in 2014, doesn't have the lethal injection drugs it needs.

So what does a state do when drugs are off the table? It invents new means of execution.

On Wednesday, officials in Oklahoma announced they plan to become the first US state to use gas to carry out capital punishment.

The proposal is that inmates condemned to death row will take turns in the chamber where a mask would be placed over their heads and nitrogen gas administered.

"We can no longer sit on the sidelines and wait on the drugs," State Attorney-General Mike Hunter said.

"Using nitrogen will be effective, simple to administer, easy to obtain and requires no complex medical procedures."

He said the death would be painless, but others went as far as saying it would be "euphoric".

Oklahoma turned to nitrogen gas after months of unsuccessfully searching for lethal injection drugs. They were forced to do so after a Supreme Court ruled the drugs used to execute Lockett were no longer legal.

Oklahoma Corrections Director Joe Allbaugh said he'd searched everywhere for other drugs but couldn't find any.

"I was calling all around the world, to the backstreets of the Indian subcontinent," Mr Allbaugh said. He said he was forced to deal with "seedy individuals" but the solution was at hand all along.

In 2015, the Senate Judiciary Committee in Oklahoma voted 9-0 to authorise death by nitrogen hypoxia. The Republican who wrote the bill, Mike Christian, described the death by toxic gas as a "euphoric feeling".

That's a far cry from what convicted murderer and rapist Clayton Lockett felt for 43 minutes on April 29, 2014.

Clayton Lockett died of a heart attack after his execution was botched.
Clayton Lockett died of a heart attack after his execution was botched.

BLINKING, WRITHING, ATTEMPTING TO LIFT HIS HEAD

Lockett, 38, was convicted of kidnapping, beating, raping, shooting and burying alive a 19-year-old woman and sentenced to death. His execution was supposed to be simple but turned into a nightmare for the inmate, those administering the drugs and the state's politicians.

At 6.23pm, Lockett was administered with a sedative. It took 10 minutes for doctors to declare him unconscious. He wasn't.

Doctors tried to administer three lethal drugs - a cocktail they were using for the first time - but 20 minutes into the execution the prisoner was still not dead. Lockett was lifting his head and writhing on the bed.

The execution was called off before Lockett died at 7.06pm from a heart attack. Autopsy results showed Lockett's vein had collapsed and the drugs had absorbed into his tissue.

Reporter Bailey Elise McBride witnessed the execution and said Lockett was "conscious and blinking, licking his lips even after the process began". She said he was unconscious at 6.33pm and "began to nod, mumble, move body" at 6.34pm.

The execution of Lockett was controversial before it started. He and fellow prisoner Charles Warner were to be executed in the state's first double execution in 80 years. Not only that, they were to be the first people executed using the state's new three-drug method.

Lockett's was not the only mishap on Oklahoma's death row. One inmate was executed with an unapproved drug in 2015 and a second inmate was just moments away from being led to the death chamber before prison officials realised the same wrong drug had been delivered for his execution.

Oklahoma Attorney-General Mike Hunter, left, and Joe Allbaugh, the director of the Oklahoma Corrections Department. Picture: Jim Beckel/The Oklahoman via AP
Oklahoma Attorney-General Mike Hunter, left, and Joe Allbaugh, the director of the Oklahoma Corrections Department. Picture: Jim Beckel/The Oklahoman via AP

BRINGING BACK THE GAS CHAMBER

Oklahoma removed the gas chamber decades ago in favour of lethal injection so Wednesday's announcement reverses that decision. Mr Hunter says it's the right call and that there's a growing body of research on the use of inert gases on humans, but not everybody agrees.

Dale Baich, a lawyer representing death row inmates in a federal case against the state's lethal injection protocol, says it's "experimental" and dangerous.

"How can we trust Oklahoma to get this right when the state's recent history reveals a culture of carelessness and mistakes in executions?"

The state is hamstrung in some ways. Any attempt to change the method used to execute inmates would trigger a flurry of legal challenges.

The Attorney-General's office has said in court filings that it will not request any execution dates until at least five months after the new protocols are released. Meanwhile, 17 death row inmates in Oklahoma have exhausted all of their appeals and are awaiting execution dates to be set.

Most of them are pictured here, a morbid collection of mug shots compiled by a local news organisation detailing what the inmates are convicted of and how long they've been waiting to die on death row.

If all goes to plan and the gas chamber is returned, they'll be the first inmates to die from nitrogen gas in US history.

- with AAP



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