The Oklahoma inmate who died of a heart attack after the state botched his execution had to be injected in his groin because doctors couldn't find a viable vein anywhere else.

Prison authorities say Clayton Lockett was Tasered the morning of his execution when an emergency response team discovered he had intentionally sliced open his right arm. He was transferred to a medical facility, where guards checked on him every 15 minutes. Lockett, who was reportedly fighting his restraints, refused to eat or speak to lawyers.

When the execution began, the phlebotomist was unable to find a suitable vein in his arms, legs, or feet and eventually had to inject him in his groin. Within 20 minutes of the injection, the curtains were lowered because Lockett had begun to convulse and call out.

[Prisons chief Robert] Patton, who was present at the execution, asked the doctor whether enough drugs had been administered to kill Lockett; the doctor said no. Patton then asked whether another vein was available and whether there were enough drugs remaining to continue; the doctor said no to both questions. The doctor then said Lockett had a faint heartbeat and was unconscious.

Patton eventually called off the execution and within ten minutes, Lockett was pronounced dead.

[image via AP]