For the purpose of any hearing, investigation, or other proceeding authorized or directed under this chapter, or relative to any other matter within its jurisdiction under this chapter, the system or administrative law judge may issue subpoenas requiring the attendance and testimony of witnesses and the production of any evidence that relates to any matter under investigation or in question before the system. Attendance of witnesses and production of evidence at the designated place of the hearing, investigation, or other proceedings may be required from any political subdivision in the state. Subpoenas of the system shall be served by anyone authorized by it by delivering a copy of the subpoena to the individual named in it, or by certified mail addressed to the individual at the individual’s last known dwelling place or principal place of business. A verified return by the individual serving the subpoena setting forth the manner of service, or in the case of service by certified mail, the return post office receipt signed by the individual served, shall be proof of service. Witnesses subpoenaed shall be paid the same fees and mileage as are paid witnesses in the district courts of the state of Iowa. In the discharge of the duties imposed by this chapter, the system or an administrative law judge and any duly authorized representative or member of the system may administer oaths and affirmations, take depositions, certify to official acts, and issue subpoenas to compel the attendance of witnesses and the production of books, papers, correspondence, memoranda, and other records deemed necessary as evidence in connection with the administration of this chapter.