CHICAGO (AP) – The FBI searched the campus police station at Northern Illinois University on Wednesday, weeks after a former NIU police officer was indicted on sexual assault charges and the department police chief was fired.

NIU spokesman Joe King said authorities were at the station, but he declined to elaborate. FBI spokeswoman Joan Hyde said only that search warrants were executed on campus in “an ongoing criminal investigation” involving Illinois State Police, the U.S. Department of Education and U.S. Department of Housing and Urban Development.

The university fired police chief Donald Grady from his $200,000-a-year job on Feb. 19, saying he mishandled evidence in an investigation into allegations that a campus police officer had sexually assaulted a student in October 2011. A DeKalb County grand jury indicted the 25-year-old former police officer, Andrew Rifkin, later in February.