Longtime Shakopee Fire Chief Rick Coleman announced his resignation and retirement Monday after the city launched an investigation in alleged misconduct.

Coleman became the subject of the misconduct investigation Dec. 6, following a citizen complaint, said city spokesperson Amanda McKnight.

McKnight said she could not share the reason for the investigation, which remains open because the city attorney is "tying up a few loose ends."

Assistant Fire Chief Ryan Yttreness has been appointed acting fire chief, McKnight said.

The City Council must officially accept Coleman's resignation; the item appears on the agenda for Tuesday night's council meeting.

Coleman has been with the department for 35 years and served as chief since 2014.

A phone call to Coleman was not immediately returned Tuesday.