Mich. Comp. Laws § 28.3

Sec. 3. The commissioner may appoint or designate 3 officers from among the 10 highest ranking commissioned officers of the department to serve in the order of precedence, as named, as acting commissioner in his absence from the aforesaid office, during his illness and/or during his disability for any reason to perform his duties: Provided, however, That any such officer so acting shall receive no additional compensation by virtue thereof. An officer appointed or designated or serving as acting commissioner may be relieved from such appointment or designation or service at the will of the commissioner.