Mich. Comp. Laws § 38.2307

Sec. 307. Upon the separation from service by a member or upon the death of a retirant, a retirement allowance beneficiary, or a refund beneficiary, any unclaimed retirement allowance or other money otherwise payable on account of the separation or death remains a part of the reserve in which it is deposited until claimed by the separated member, retirement allowance beneficiary, refund beneficiary, or the estate or legal representative of a separated member, retirement allowance beneficiary, or refund beneficiary.