Illinois Statutes Chapter 740. Civil Liabilities § 10/7.3. Service of subpoena

§ 7.3. Service of a subpoena of the Attorney General as provided herein may be made by (a) Delivery of a duly executed copy thereof to the person served, or if a person is not a natural person, to the principal place of business of the person to be served, or (b) Mailing by certified mail, return receipt requested, a duly executed copy thereof addressed to the person to be served at his principal place of business in this State, or, if said person has no place of business in the State, to his principal office.