405 ILCS 5/5-103
The Department, or any health officer of this State or any municipality where any person subject to involuntary admission or who meets the standard for judicial admission may be, may inquire into the manner in which any such person who is not a recipient of services in a state facility is cared for and maintained. Whenever the Department has reason to believe that any person asserted or adjudged to be subject to involuntary admission or to meet the standard for judicial admission is confined and may be wrongfully deprived of his liberty, or is cruelly, negligently or improperly treated, or that inadequate provision is made for his care, supervision and safekeeping, it may ascertain the facts or may order an investigation of the facts. The Department, or any duly authorized representative of the Department, may at any time visit and examine the persons in any place to ascertain if persons subject to involuntary admission or who meet the standard for judicial admission are kept therein. The Secretary, or any duly authorized representative of the Department conducting the investigation, may administer oaths and issue subpoenas requiring the attendance of and the giving of testimony by witnesses and subpoenas duces tecum requiring the production of books, papers, records, or memoranda. All subpoenas issued under this Act may be served by any person 18 years of age or older. The fees of witnesses for attendance and travel are the same as the fees of witnesses before the circuit courts of this State. Such fees are to be paid when the witness is excused from further attendance. When the witness is subpoenaed at the instance of the Department or any officer or employee thereof, such fees shall be paid in the same manner as other expenses of the Department, and when the witness is subpoenaed at the instance of any other party to any such proceeding the Department may require that the cost of service of the subpoena and the fee of the witness be borne by such party. In such case the Department, in its discretion, may require a deposit to cover the cost of such service and witness fees. A subpoena issued under this Section must be served in the same manner as a subpoena issued out of a court.
Any court of this State, upon the application of the Department or any officer or employee thereof may compel the attendance of witnesses, the production of books, papers, records, or memoranda and the giving of testimony before the Department or any officer or employee thereof conducting an investigation or holding a hearing authorized by this Act, by an attachment for contempt, or otherwise, in the same manner as production of evidence may be compelled before that court. The Department or any officer or employee thereof, or any party interested in an investigation or hearing before the Department, may cause the depositions of witnesses residing within or without the State to be taken in the manner prescribed by law for like depositions in civil actions in courts of this State and, to that end, compel the attendance of witnesses and the production of books, papers, records or memoranda.
Whenever the Department undertakes an investigation into the general management and administration of any facility, it may give notice to the Attorney General who shall appear personally or by an assistant and examine witnesses who may be in attendance and otherwise represent the Department in such investigation.
Any recipient's records or confidential communications disclosed under this Section or under proceedings pursuant thereto shall not lose their confidential and privileged character as established by the "Mental Health and Developmental Disabilities Confidentiality Act", enacted by the 80th General Assembly; such records or confidential communications shall not be utilized for any other purpose nor be redisclosed or otherwise discoverable except in connection with such investigation and proceedings pursuant thereto.
405 ILCS 5/5-103