Departure comes as the state investigates what went wrong during Pike's lethal injection.

Tennessee's top prison official, Frank Strada, resigned days after the failed execution of death row inmate Christa Pike. Gov. Bill Lee announced Strada would step down this month, cooperating with an independent investigation. Pike, 50, survived two doses of pentobarbital and was hospitalized. Strada said he acted per protocol but stepped aside for Tennesseans.