The Oklahoma Department of Corrections botched the execution of convicted killer Clayton Lockett Tuesday night, claiming the execution didn't go as planned because of a blown vein.

It was determined he was sedated approximately seven minutes into the execution," DOC Director Robert Patton said. "At that time we began pushing the second and third drugs in the protocol. There was some concern at that time that the drugs were not having the effect, so the doctor observed the line and determined that the line had blown."The second drug in the protocol was vecuronium bromide, which is a paralytic used to stop Lockett's breathing. The third drug in the protocol was potassium chloride, which was used to stop Lockett's heart.Witnesses described a disturbing chain of events that followed. They said Lockett was not unconscious until 6:33, but at 6:36 they said Lockett became conscious again and was mumbling, his muscles tightened, his mouth opened and he was twitching. At 6:37 witnesses say Lockett said "something is wrong." Lockett continued mumbling and moving, even lifting his head and shoulders until 6:39, when DOC officials closed the blinds to keep witnesses from seeing any more.Using newspaper accounts and a database of all American executions, my collaborators and I recently completed the first comprehensive study of botched executions in the United States and documented the ways that different methods of execution go wrong. We examined every execution from 1890 to 2010 and found that no technology has been able to ensure that capital punishment would not, on occasion, become either a gruesome spectacle of suffering or a messy display of incompetence

Austin Sarat "Gruseome Spectacles: Botched Executions and America’s Death Penalty"