10 ILCS 5/4-18
The county clerk on his or her own initiative or upon the order of the county board or of the circuit court shall at all times have authority to conduct investigations and to make canvasses of the registered voters in any precinct by other methods than those prescribed herein, and shall at all times have authority to cancel registration in the manner provided by this section. Canvassers appointed for such canvasses and investigations shall be appointed by the county clerk; shall be confirmed by the circuit court in the manner provided by Section 13--3 of this Act for the confirmation of judges of election; shall be officers of that court; and shall be subject to the same control and punishment as judges of election. If upon the basis of investigation or canvasses, the county clerk is of the opinion that any person registered under this Article 4 is not a qualified voter or has ceased to be a qualified voter, he or she shall send a notice through the United States mail to such person, requiring him or her to appear before the county clerk for a hearing within 5 days after the date of mailing the notice and show cause why his or her registration shall not be cancelled. If such person fails to appear within such time as provided, his or her registration shall be cancelled. If such person does appear, he or she shall execute an affidavit similar in every respect to the affidavit required of applicants under Section 4--13 of this Article 4.
10 ILCS 5/4-18