By Jon Herskovitz
(Reuters) - Oklahoma's Department of Corrections director resigned on Friday after a term in office in which troubles in the state's death chamber led to a halt in executions and raised questions about the death penalty in the United States.
Robert Patton, in the job since January 2014, has accepted a position in Arizona to be closer to his family, the Oklahoma Department of Corrections said in a statement.
Oklahoma agreed in October to put the executions of three death row inmates on hold until well into 2016 or even longer to investigate problems with death chamber protocols after the wrong drug was provided in September for use in a scheduled lethal injection.
The state revised its death chamber protocols in 2014 after a flawed execution in April of that year, when medical staff did not properly place an intravenous line on convicted murderer Clayton Lockett, who was seen twisting in pain on the gurney.
He died about 45 minutes after the procedure began.
Since then, one other execution was carried out, of child rapist and murderer Charles Warner.
In that execution, authorities used a drug not included in the state's official protocol, the Oklahoman newspaper reported in October. Governor Mary Fallin later said there were possible problems with that execution.
Since the U.S. Supreme Court reinstated the death penalty in 1976, Oklahoma has executed 112 inmates. It ranks second in executions among U.S. states after Texas, according to the Death Penalty Information Center, which monitors capital punishment.
(Additional reporting by Heide Brandes in Oklahoma City; Editing by Dan Grebler)