HOUSTON (AP) — The mayor of Houston has accepted the retirement of the city’s police chief as the department investigates why thousands of cases including sexual assault crimes were dropped, a city spokesperson said Wednesday.

Mayor John Whitmire accepted the retirement of Police Chief Troy Finner, who is stepping away following reports Tuesday that he was aware of a code used to drop the cases, years before acknowledging its existence.

Whitmire appointed assistant Chief Larry Satterwhite as acting chief and will discuss the chief’s retirement during a City Council meeting Wednesday, according to spokesperson Mary Benton.

Finner’s retirement comes as police investigate the dropping of more 4,000 sexual assault cases that are among more than 264,000 incident reports never submitted for investigation due to staffing issues during the past eight years.