The United Nations human rights office on Friday condemned the bungled and chaotic execution of an Oklahoma death-row inmate, which left him thrashing on the gurney during a chaotic process that lasted nearly two hours.

A spokesman for the UN high commissioner for human rights in Geneva said that the process to which Clayton Lockett was subjected on Tuesday may have amounted to "cruel, inhuman and degrading treatment" under international human rights law, and may have violated the US constitution.

Barack Obama admitted on Friday that the manner of Lockett's execution was "deeply troubling" and said he had asked the US attorney general, Eric Holder, to provide a review of the issues raised by it. "I do think as a society we have to ask ourselves some difficult questions," he said.

A timeline published by the state of Oklahoma on Thursday showed that medical staff could not find a suitable vein on any of his limbs in which to inject the lethal drugs intended to kill him, and had to use his groin instead, which they covered, to prevent that area of his body from being seen by witnesses.



The intravenous line into his groin failed, but the failure was not picked up for 21 minutes when the sheet was pulled back. The Guardian was among witnesses who watched as, for three minutes, Lockett fought against his restraints and attempted to speak, despite having been officially declared unconscious. When the IV failure was eventually discovered, it was found that the lethal drugs may not have entered Lockett correctly. "The drugs had either absorbed into tissue, leaked out or both," wrote the Oklahoma prisons director, Robert Patton in the timeline.

Lockett eventually died, apparently of a massive heart attack, one hour and 44 minutes after first being strapped to the gurney and ten minutes after the execution was officially called off. The state has refused to say whether, as required by its execution protocol, any attempts were then made to revive Lockett.

"The suffering of Clayton Lockett during his execution in Oklahoma on Tuesday, 29 April, may amount to cruel, inhuman and degrading treatment according to international human rights law," said Rupert Colville, spokesman for the UN high commissioner for human rights.

Colville said that the execution also appeared to run counter to the US constitution, which bars "cruel and unusual punishment". He told reporters: "The prolonged death of Clayton Lockett is the second case of apparent extreme suffering caused by malfunctioning lethal injections reported in 2014 in the United States," referring to the case of Dennis McGuire, executed in Ohio in January with an allegedly untested combination of drugs. "The apparent cruelty involved in these recent executions simply reinforces the argument that authorities across the United States should impose an immediate moratorium on the use of the death penalty and work for abolition of this cruel and inhuman practice," said Colville. Of the 50 states in the US, 32 still have the death penalty in their laws, in addition to the US federal government and the military. Eighteen states have abolished the death penalty, most recently Maryland in 2013 and Connecticut in 2012. "The UN opposes the use of the death penalty in all circumstances," Colville said.

Lockett was convicted in 2000 and sentenced to death for the kidnap and murder of a 19-year-old, Stephanie Neiman, during a home invasion the previous year. She survived the initial assault, and Lockett ordered two accomplices to bury her alive. He also raped one of her friends. His accomplices are serving life sentences.

Neiman had graduated from high school only two weeks before her death. Her parents, Steve and Susie Neiman, supported Lockett's sentence. After his death on Tuesday, the Neimans issued a statement, saying: “We are thankful this day has finally arrived and justice will finally be served.”

Speaking at a news conference with German chancellor Angela Merkel at the White House, Obama noted that Lockett had been convicted of "heinous crimes" and that there were certain circumstances in which the death penalty may be appropriate. But he added: "What happened in Oklahoma is deeply troubling."

The use of the death penalty in the US had been plagued with "significant problems" including racial bias, uneven application and the discovery of that death-row inmates were innocent. "This situation in Oklahoma, I think, just highlights some of the significant problems there." Obama said he had asked Holder for an "analysis of what steps have been taken not just this case, but more generally". He did not go into any more details.

After Lockett's execution went awry, Robert Patton, the Oklahoma prisons director recommended an indefinite stay of executions in the state until procedures for judicial killings are completely rewritten and staff retrained. The Republican governor of Oklahoma, Mary Fallin, has agreed to use her powers to impose a 60-day stay, after which the attorney general would need to seek a court ruling.

"After exhaustion of the governor's 60-day authority for granting stays for any potential executions, the attorney general would make any appropriate filing with the court of criminal appeals," said Diane Clay, spokeswoman for attorney general Scott Pruitt on Friday.



The timeline published by Oklahoma details a chaotic scene in the death chamber before and during the failed execution on Tuesday. Earlier in the day, Lockett had fought with prison guards as they tried to take him for an x-ray. He was Tasered, and found to have slashed his own arm.



Lockett was taken to the execution chamber just after 5pm, and strapped to the gurney at 5.22pm. But a suitable vein could not be found anywhere on his body in which to insert an intravenous line. Veins on his legs and arms were rejected before a doctor examined his neck, and then finally his groin. This process took 51 minutes.

The timeline reveals that the insertion point was covered by a sheet “to prevent witness viewing of the groin area”. The execution began at 6.23pm with the injection of the first of a cocktail of three drugs, but the intravenous line – covered by the sheet – was only checked after 6.44pm, when the blinds between the execution chamber and the viewing room were lowered.

The report says: “The doctor checked the IV and reported the blood vein had collapsed, and the drugs had either absorbed into tissue, leaked out or both. The warden immediately contacted the director by phone and reported the information to the director.”

According to the timeline, Patton asked if enough drugs had been administered to cause death, to which the doctor replied “no”. The director then asked if another vein was available to complete the execution, and if so, were there enough drugs left. The doctor answered no to both questions, the timeline reveals.

The doctor reported a “faint heartbeat”, and at 6.56pm, Patton called off the execution. The timeline does not detail what happened between then and 7.06pm, when Lockett was declared dead, one hour and 44 minutes after first being restrained on the execution table.

The state's execution protocol requires that attempts be made to revive an inmate if the execution process is called off. At an open meeting of the board of corrections on Thursday, Patton refused to answer a question from the Guardian about whether any attempts were made to revive Lockett, and walked out of the room.

AFP in Geneva contributed to this report