In May 2014, Oklahoma Director of Corrections, Robert Patton, recommended an indefinite hold on executions in the state after the botched execution of African-American Clayton Lockett. The prisoner had to be tasered to restrain him prior to the execution, and the lethal injection missed a vein in his groin, resulting in Lockett regaining consciousness, trying to get up, and to speak, before dying of a heart attack 43 minutes later, after the attempted execution had been called off. In 2015, the state approved nitrogen asphyxiation as a method of execution.
What state employed Robert Patton in May 2014? (If the question is unanswerable, say "unanswerable")
Oklahoma