Mich. Comp. Laws § 780.754

Sec. 4. (1) The law enforcement agency having responsibility for investigating a reported crime shall promptly return to the victim property belonging to that victim which is taken in the course of the investigation, except as provided in subsections (2) to (4). (2) The agency shall not return property which is contraband. (3) The agency shall not return property if the ownership of the property is disputed until the dispute is resolved. (4) The agency shall retain as evidence any weapon used in the commission of the crime and any other evidence if the prosecuting attorney certifies that there is a need to retain that evidence in lieu of a photograph or other means of memorializing its possession by the agency.