Michigan Compiled Laws, Chapter 567. Escheats § 567.237

Sec. 17.Except as otherwise provided in section 17a,  1 all property held in a safe deposit box or any other safekeeping repository in this state in the ordinary course of the holder's business and proceeds resulting from the sale of the property permitted by law, that remain unclaimed by the owner for more than 3 years after the lease or rental period on the box or other repository has expired, are presumed abandoned.