65 ILCS 5/4-5-6
In all municipalities in which Sections 10-1-1 through 10-1-45 are not in effect, all officers, assistants, and employees of each department specified in Section 4-5-2, except those elected or appointed as provided in Sections 4-5-3 through 4-5-5, shall be appointed by the commissioner of the department to which they are appointed, and may be discharged by him when in his judgment the efficient conduct of municipal affairs so demands. However, in all municipalities in which Sections 10-1-1 through 10-1-45 and Sections 10-2-1 through 10-2-23 are not in effect, all officers and members of the fire and police departments, except those elected or appointed as provided in Sections 4-5-3 through 4-5-5, shall be appointed by the commissioner of the department, specified in Section 4-5-2, to which the powers of and duties to be performed by the fire department and the police department, respectively, are assigned, and may be discharged by him when in his judgment the efficient conduct of municipal affairs so demands.
65 ILCS 5/4-5-6