20 ILCS 5/5-655

The directors of departments (see Section 5-10 of this Law for the definition of "director") shall devise a practical and working basis for co-operation and co-ordination of work, eliminating duplication and overlapping of functions. They shall, so far as practicable, co-operate with each other in the employment of services and the use of quarters and equipment. The director of any department may empower or require an employee of another department, subject to the consent of the superior officer of the employee, to perform any duty that the director might require of his or her own subordinates. The directors of departments may co-operate in the investigation of any licensed health care professional or may jointly investigate such a person and may share the results of any cooperative, joint, or independent investigation of such a person.