A trial board to hear charges against officers of the department consisting of the commissioner and 3 officers from among the 10 commissioned officers of the department, senior in service, shall be appointed by the commissioner. The commissioner shall be the presiding officer thereof and make all necessary rulings during the course of any hearing. He shall also make rules and regulations for the filing of verified written charges against an accused officer, for a due hearing thereon upon not less than 10 days notice and for an opportunity to the officer to produce proof in his defense. Such hearing may be held at any place designated by the commissioner.

     The commissioner or the officer acting in his stead as presiding officer of the trial board is empowered to issue subpoenas to compel the attendance of witnesses and the production of evidence in support of charges, and shall issue subpoenas for witnesses for the defense and shall on his own motion if he have knowledge or be informed of other persons having knowledge of the matters charged compel their attendance at the hearing by subpoena. Persons summoned as witnesses before the trial board shall be entitled to witness fees and mileage for traveling, as provided by law for witnesses in courts of record in the county in which the hearing is held, and failure or refusal to obey any such subpoena shall be brought to the attention of the circuit court of the county wherein the hearing is held, and shall be punished by said court as a contempt. Upon written order of the commissioner, any officer appointed or designated to act in his absence as acting commissioner may sit in his place and stead as presiding officer of said trial board. If the charges be proved the trial board shall make a finding of guilty and recommend either removal of the officer or such disciplinary punishment as prescribed by the rules and regulations which, in their opinion, the offense merits; thereupon the commissioner shall direct such removal or punishment. If any officer refuses to abide by any such disciplinary order, the commissioner may by order remove him forthwith. Nothing herein contained shall require a hearing before said board before disciplinary measures may be taken by the commissioner or any commanding officer of a detachment or unit for the punishment of minor infractions of the rules and regulations of the department.