DENVER (AP) – Officials have tapped former Arapahoe County Sheriff Grayson Robinson to oversee the Denver Sheriff Department’s beleaguered internal affairs bureau.

The Monday announcement comes as the department tries to make sweeping changes after a series of excessive force and misconduct cases. Safety Director Stephanie O’Malley says there are about 150 pending internal affairs cases, and the city wants to hire seven on-call investigators to handle the backlog. Robinson will lead the unit on an interim basis.

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Robinson, who spent 43 years in law enforcement, retired in February after leading the investigation into the deadly shooting at Arapahoe High School. He also oversaw the detention of Colorado theater shooting suspect James Holmes.

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Robinson serves on the board of the National Police Research Platform, part of the Justice Department’s National Institute of Justice.

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