An attorney for a man whose execution appeared to have been botched has asked Georgia’s chief justice to stop any more lethal injections until the Department of Corrections investigates what went wrong Thursday night.

Attorney Brian Kammer also wrote Corrections Commissioner Brian Owens on Friday asking for “an immediate independent investigation into what appear to have been serious problems attending the execution.”

Roy Blankenship was put to death Thursday night for the murder of 78-year-old Sarah Mims Bowen in Savannah 33 years ago. In that execution, Georgia used a new sedative, pentobarbital, as the first of three drugs.

According to witnesses, Blankenship grimaced, jerked, lunged from side-to-side, gasped and appeared to yell out during the three minutes immediately after the first drug was administered. Witnesses said his eyes remained open until the end, as had been the case with the two previous executions.

This was the first time in an execution in Georgia that a condemned man has moved once the sedative was administered. Usually their eyes are closed once the drugs begin to flow.

Blankenship's lawyer repeatedly noted in his appeals that the Danish company that makes pentobarbital has said the sedative was untested on humans and was not safely used in executions.

“DOC has had three problematic executions in a row, indicating serious and systemic problems in how DOC administers judicial lethal injections and that DOC cannot assure a humane, constitutional execution process,” Kammer wrote in his letter to Georgia Supreme Court Chief Justice Carol Hunstein.

Kammer wrote in his letter to Owens, “it is unconscionable to allow any further lethal injections to proceed until you have determined what is going wrong.”

The Department of Corrections said in an email the agency will consult the state's lawyers and medical experts "to ensure our execution procedures are medically appropriate... We remain confident in our ability to carry out humane and dignified executions."