The law;
http://www.legislature.mi.gov/(S(uqonzjgs0x54itb15luw3gnl))/mileg.aspx?page=getObject&objectName=mcl-434-22
Sec. 2.
(1) A person who finds lost property shall report the finding or deliver the property to a law enforcement agency in the jurisdiction where the property is found. This shall include all property found in an abandoned vehicle. If the person wishes to receive the property if it is not claimed by the legal owner as provided in this act, the person shall provide his or her name and current address to the law enforcement agency and shall inform the agency of any change in his or her address.