225 ILCS 640/15
The Department may, upon its own motion, and shall, upon the complaint in writing of any person setting forth facts which if proved would constitute grounds under Section 6, investigate the actions of any applicant, registrant, or person claiming to be registered under this Act. At least 10 days before the date set for hearing, the Department shall, before refusing to issue or renew and before suspension or revocation of a registration, notify in writing the applicant for or holder of a registration, called in this Section the respondent, that on the date designated a hearing will be held to determine whether the respondent is privileged to be registered. The written notice shall be served personally on the respondent or by registered or certified mail sent to the respondent's business address as shown in his or her latest notification to the Department.
The Department, over the signature of the Director, is authorized to subpoena and bring before the Department any person or persons in this State and to take testimony either orally or by deposition or by exhibit, with the same fees and mileage and in the same manner as prescribed by law in judicial proceedings in civil cases in circuit courts of this State. The Director may issue subpoenas duces tecum to command the production of any or all records relating to the person.
225 ILCS 640/15