Charges of inefficiency or misconduct may be filed with the secretary of the commission by a superior officer or by the appointing authority, and thereupon the commission shall try the charges after no less than ten days' written notice to the accused. Such notice shall set forth the charges as filed. The trial of these charges shall be open to the public and each commissioner shall have the power to issue subpoenas and to administer oaths and to compel the attendance and testimony of witnesses and the production of books and papers relevant to the investigation. The commission shall require by subpoena the attendance of any witness requested by the accused who can be found in the county in which such city is located. The commission may make complaint to the district court of disobedience of its subpoenas or orders under this section, and the court shall prescribe notice to the person accused and require the accused person to obey the commission's subpoena and order, if found within the lawful powers of the commission, and punish disobedience as a contempt of court. Witnesses shall be entitled to the same fees and mileage as for attendance upon the district court, except that any officer, agent, or employee of the city who receives compensation for services, shall not be entitled to fees or mileage.