55 ILCS 5/3-8010
The appointment of all personnel subject to the jurisdiction of the Merit Commission shall be made by the sheriff from those applicants who have been certified by the Commission as being qualified for appointment. A Commission may, by its rules and regulations, set forth the minimum requirements for appointment to any position. In addition, the Commission's review of any application may include examinations, investigations or any other method consistent with recognized merit principles, which in the judgment of the Commission is reasonable and practical for any particular classification. Different examining procedures may be set for the examinations in different classifications but all examinations in the same classification shall be uniform. However, the Merit Commission may by regulation provide that applicants who have served with another sheriff's office, a police department, or any other law enforcement agency, or who are graduate law enforcement interns as defined in the Law Enforcement Intern Training Act, may be exempt from one or more of the minimum requirements for appointment. Preference may be given in such appointments to persons who have honorably served in the military or naval services of the United States.
The sheriff shall make appointments from those persons certified by the Commission as qualified for appointment. If the sheriff rejects any person so certified, the sheriff shall notify the Commission in writing of such rejection.
The rules and regulations of a Commission shall provide that all initial appointees shall serve a probationary period of 12 months during which time they may be discharged at the will of the sheriff.
55 ILCS 5/3-8010