55 ILCS 5/3-6019
Sheriffs shall serve and execute, within their respective counties, and return all warrants, process, orders and judgments of every description that may be legally directed or delivered to them. A sheriff of a county with a population of less than 1,000,000 may employ civilian personnel to serve process in civil matters. If an arrest warrant upon complaint under Section 107-9 of the Code of Criminal Procedure of 1963, or a warrant of arrest due to failure to appear under Section 107-12 of the Code, originated from a law enforcement agency other than the county sheriff's office, then the county sheriff of a county with a population of more than 600,000 may require that law enforcement agency to store and maintain the warrant. That law enforcement agency is responsible for entering the warrant into the Illinois Law Enforcement Agencies Data System (LEADS) and the National Crime Information Center Database (NCIC). The county sheriff may require the originating law enforcement agency to arrange for transportation of the wanted person to the county jail. Originating agencies may contract with the county sheriff or another law enforcement agency to store, maintain, and provide transportation of the wanted person to the county jail. Any law enforcement agency or regional dispatch center may act as holder of the warrant for an originating agency that has no telecommunications equipment.
Each sheriff shall keep and maintain his or her office at the county seat of the county for which he or she is the sheriff, and shall in counties having a population of less than 500,000 keep his or her office open and attend to the duties thereof from 8 o'clock in the forenoon to 5 o'clock in the afternoon of each working day, excepting such days and half days as, under any law, are or may be legal holidays, or half holidays. The hours of opening and closing of the office of the sheriff may be changed and otherwise fixed and determined by the county board of such county. Such action taken by the county board shall be by an appropriate resolution passed at a regular meeting.
55 ILCS 5/3-6019