615 ILCS 50/10

The Department of Natural Resources may make such investigations and conduct such hearings as may be necessary to the performance of its duties under this Act. The Department may issue subpoenas, and may administer oaths in connection with such investigations and hearings. Any person served with a subpoena to appear and testify, or to produce books or papers or reports, and who shall refuse or neglect to appear or to testify, or to produce books or papers or reports, as commanded in such subpoena shall be guilty of a Class B misdemeanor.