Roy Willard Blankenship jerked his head several times throughout Thursday's procedure, which used pentobarbital as part of the three-drug combination for the first time in Georgia. One expert said Blankenship's movements were a signal the execution was botched, while another suggested it could have been a side effect of the drug.
Defense attorney Brian Kammer claimed before the execution that using the drug would risk needless suffering. In separate filings Friday, he asked state prison officials to launch an independent investigation and urged the Georgia Supreme Court to halt all executions in the state pending the outcome.
"This problem is obviously capable of repetition while evading review, and it is unconscionable to allow further lethal injections to proceed" until prison officials determine what happened, he said in his petition to the court.
The state, he said, has proven that it "cannot assure a humane, constitutional execution process."
Department of Corrections spokeswoman Kristen Stancil declined to comment on whether it would launch an investigation, saying only that officials will work with the Attorney General's office and medical experts to ensure "execution procedures are medically appropriate."
She said Georgia used the same protocol adopted by other states that have switched to pentobarbital.
"We remain confident in our ability to carry out humane and dignified executions," she said.
Blankenship's execution has set off a debate in the legal community and aroused the scrutiny of medical experts.
"They clearly botched this execution and Mr. Blankenship clearly suffered," said Dr. David Waisel, a Harvard medical professor who has raised questions about using pentobarbital.
"Whether it was due to incompetent performance or whether it was due to the fact that the drug didn't work as the state claimed it would, something went wrong."
Blankenship's movements could also have come during an "excitement phase" that takes hold before a patient slips into unconsciousness after receiving a powerful sedative, said Dr. Howard Nearman, the chairman of the anesthesiology department at Case Western Reserve University School of Medicine in Cleveland.
"As he's going to sleep, there could be many kinds of reactions. He could have had the same reaction with sodium thiopental," Nearman said. "And he could have been faking it. Anything's possible."
Georgia has joined a growing number of death penalty states that use pentobarbital in executions amid a supply shortage of sodium thiopental. That drug was long used in Georgia and other states as the first part of a three-drug execution combination.
The state was forced to switch to pentobarbital this month after the state surrendered its supply of sodium thiopental to Drug Enforcement Administration officials amid an investigation into how prison officials obtained the drug. The probe is still pending.
But critics have long claimed that using pentobarbital could risk violating the ban on cruel and unusual punishment, and Thursday's execution isn't likely to lessen that criticism.
Blankenship was put to death for the 1978 murder of Sarah Mims Bowen, who died of heart failure after she was sexually assaulted in her Savannah apartment.
BEFORE THE EXECUTION , Blankenship was laughing and chatting with a prison chaplain, and at one point he tried to converse with the observers sitting behind a glass window, seemingly unaware that they couldn't hear him.
That changed as the injection began. First, he jerked his head toward his left arm and made a startled face while blinking rapidly. His mouth tightened, and he lurched to his right arm, and then lunged twice with his mouth wide open.
He then pushed his head forward and his chin smacked as he mouthed words that were inaudible to observers. His eyes never closed.
Blankenship's movements stopped within three minutes after the lethal injection started, and his breathing slowed. He was unconscious about six minutes after it started, and pronounced dead about nine minutes later.