Tennessee hasn't yet revealed exactly what went wrong when the state failed to kill Christa Pike on Sept. 30, despite staff injecting two lethal doses into her arm. Republican Gov. Bill Lee has since paused all executions and called for an independent review of the state's lethal injection protocols, and Pike is still alive.

But Pike's attempted execution was not the only one badly mishandled under the leadership of Frank Strada, Tennessee's top prison commissioner, whose resignation was announced on Oct. 3. A similar review had already been conducted in Arizona, where three lethal injection executions were bungled while Strada was the deputy director of the Arizona Department of Corrections, Rehabilitation & Reentry.

How those executions were carried out holds clues to what may have happened behind closed doors during Pike's attempted execution.