720 ILCS 5/14-8

Discovery of eavesdropping device by an individual, common carrier, private investigative agency or non-governmental corporation). Any agent, officer or employee of a private investigative agency or non-governmental corporation, or of a common carrier by wire, or any individual, who discovers any physical evidence of an eavesdropping device being used which such person does not know to be a legal eavesdropping device shall, within a reasonable time after such discovery disclose the existence of such eavesdropping device to the State's Attorney of the county where such device was found. The State's Attorney shall within a reasonable time notify the person or persons apparently being eavesdropped upon of the existence of that device if the device is illegal. A violation of this Section is a Business Offense for which a fine shall be imposed not to exceed $500.