35 ILCS 128/1-65
No person shall be excused from testifying or from producing any books, papers, records, or memoranda in any investigation or upon any hearing, when ordered to do so by the Department or any officer or employee thereof, upon the ground that the testimony or evidence, documentary or otherwise, may tend to incriminate him or subject him to a criminal penalty, but no person shall be prosecuted or subjected to any criminal penalty for or on account of the subject matter of his or her testimony or the evidence produced before the Department or an officer or employee of the Department; provided that such immunity shall extend only to a natural person who, in obedience to a subpoena, gives testimony under oath or produces evidence under oath. No person so testifying shall be exempt from prosecution and punishment for perjury committed in so testifying.
35 ILCS 128/1-65