Robert Patton, the director of the Oklahoma Department of Corrections, announced on Friday that he will resign from his post. The move comes amid a grand jury investigation into state's execution practices. Patton's tenure—which only lasted a year and a half—saw several executions go wrong. (Twice executioners had the wrong drug and one inmate took 45 minutes to die.) Patton's departure marks the second high-profile resignation from the state's corrections department in recent months as its warden resigned in October.