SIOUX FALLS, S.D. (AP) - South Dakota's director of prison operations says the April 2011 murder of a guard at the state penitentiary in Sioux Falls was one of the most difficult times of his career.

Doug Weber, who is chief warden for the Department of Corrections, is retiring this month after more than 30 years working in corrections in South Dakota.

Weber tells The Associated Press that he is leaving the position content with having made positive changes in the state's prisons.

He says one of the most challenging moments of his career came when two inmates killed prison guard Ronald Johnson during a botched prison escape. He says overseeing three executions was also difficult and unexpected.

Weber says he supports a new justice initiative that will divert low-level offenders.

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