The director of prisons in the US state of Oklahoma is calling for an indefinite stop to all executions so procedures can be revised.
In a botched exeuction earlier this week, death row inmate Clayton Lockett was left writhing in agony after he was given a new untested drug cocktail.
He died 43 minutes after the start of the lethal injection of a massive heart attack. The process usually takes 10 minutes.
AFP reports that in a letter to the Oklahoma Governor, Department of Corrections director Robert Patton recommends a "comprehensive review of the execution protocol". He said that would require a suspension of executions and recommended asking for court approval.
Mr Patton revealed that, prior to his execution, a defiant Lockett had been tasered early on Tuesday and he had also deliberately cut his arm.
Mr Patton also said that technicians had found it difficult to find a vein to insert the lethal drugs in and eventually found a "vital point" in the groin - suggesting that "the drugs were injected into Mr Lockett's flesh, rather than his veins," according to attorney Madeline Cohen.
Robert Patton's recommendations include putting decision-making in more senior hands, he said, adding: "I intend to explore best practices from other states and ensure the Oklahoma protocol adopts proven standards."