"Writhing on the gurney": What happened during this man's execution is horrifying.

Warning: This post deals with strong themes and may be upsetting for some readers.

When a prisoner is sentenced to death in the US, prisons are legally compelled to execute them “humanely”.

But what happened when the State Corrections Department of Oklahoma administered a new, untested drug cocktail to a death row inmate this week has been described as far from humane.

Clayton Lockett, 38, was alive for 43 minutes and “writhing on the gurney” when his vein exploded after the administration of a triple injection. The death row inmate was declared unconscious 10 minutes after being injected with the sedative midazolam — the first of a three-drug combination — but began breathing heavily three minutes later, The Australian reports.

The Oklahoman described the ensuing, horrifying scene like this:

“Lockett grimaced and tensed his body several times over a three-minute period before the execution was shielded from the press. After being declared unconscious 10 minutes into the process, Lockett spoke at three separate moments. The first two were inaudible, however, the third time he spoke, Lockett said the word ‘man.'”

Officials attempted to halt the procedure and after about 16 minutes had passed, they drew the blinds on the viewing chamber through which observers were watching.

Lockett eventually suffered a fatal heart attack at 7:06pm — almost three-quarters of an hour after the administration of the first injection — according to a statement from prisons spokesman Jerry Massie.

The execution of another death row inmate, Charles Warner, was stayed for 14 days following the horrifying incident.

The prison was set to use the same experimental mix of drugs on Warner as it had on Lockett.

Warner’s lawyer Madeline Cohen, who has previously argued that the new drug combination would make it “impossible to know whether the executions will comport with the Eighth Amendment’s ban on cruel and unusual suffering”, criticised the state’s role in the incident.

“After weeks of Oklahoma refusing to disclose basic information about the drugs for tonight’s lethal injection procedures, Clayton Lockett was tortured to death,” Ms Cohen said.

The botched execution has been seized upon globally by opponents of the death penalty, who branded it “torture” and “a science experiment gone wrong”.

The White House has also criticised the incident, admitting it “fell short” of the required level of humane treatment.

Press secretary Jay Carney said, “We have a fundamental standard in this country that even when the death penalty is justified, it must be carried out humanely.”

“I think everyone would recognise that this case fell short of that standard,” he said.

Oklahoma, like other states, has struggled to locate alternative sources of execution drugs since European manufacturers refused to supply the most commonly used anaesthetic, pentobarbital, for executions.

Some states – including Missouri, Virginia and Wyoming – are planning to bring back long-gone execution methods, such as gas chambers, electrocutions and firing squads, in response to the shortage.

Capital punishment is legal in 32 US states. Across the country, there are still about 3000 inmates on death row. 

New Zealand-based artist Henry Hargreaves explores the death penalty in his “No Second” photo series — where he re-creates the final meals of prisoners executed in Texas. For more photos, click here.