Mich. Comp. Laws § 38.17d
A member who retires after October 8, 1976, at the member's request shall have his or her credited service include service rendered by that member to the department of state police, or its predecessor agencies, or to a court of record in this state to the same extent that the service is credited when rendered in a position covered under this act, and if service credited when rendered in a position in a court of record of this state exceeds 5 years, and if the member pays into the employees' savings fund the contributions the member paid during that period of service with the state police or its predecessor agencies or with the court of record plus interest as established by the board and if the member relinquishes for himself or herself and the member's beneficiary all rights in and to a retirement allowance for that service rendered.
MCL 38.17d