Mich. Comp. Laws § 38.560

Sec. 10. Any and all cash assets and funds on hand not necessary for immediate payment of pensions or benefits under this act shall be invested subject to all the terms, conditions, limitations, and restrictions imposed by the statutes of this state upon life insurance companies in making and disposing of their investments, and as provided by law relating to investment authority of public employee retirement systems under Act No. 314 of the Public Acts of 1965, being sections 38.1132 to 38.1140i of the Michigan Compiled Laws, and any and all assets of every description of the pension or retirement fund created by any city, village, or municipality under this act shall be transferred and deposited to the credit of the newly created retirement system under this act.