10 ILCS 5/4-27
At each regular special or primary election to which this Article 4 is applicable, the judges of election shall personally affix all affidavits made before them in accordance with the provisions of Sections 4--15, 4--16, 4--22, 4--23, 7--45 or 17--10, respectively, to the respective applications to vote.
Persons voting for whom no registration card is found in the master file or precinct binder shall be investigated by the county clerk or persons in his office, as shall likewise be investigated the correctness of affidavits filed under the provisions of the Sections hereinbefore in this Section enumerated. If from such investigation the county clerk shall be satisfied that the provisions of this Article have been violated, or that any person has voted who was not qualified so to do, he shall make a complete report to the State's Attorney of the County, attaching thereto a correct copy of the application to vote and any affidavit which may have been executed by the voter and supporting witnesses, if any. The State's Attorney shall prosecute all such reports of fraud if on the basis of the facts so reported, and of any additional investigation he may cause to be made, he shall be satisfied that a knowing violation of this Article or of this Act has been committed. The County Clerk shall further file with the circuit court, for such action as is provided in cases of the misbehavior of judges of election, a copy of any such report in which it shall appear that the judges of election knowingly permitted a person to vote who was not qualified so to do under the provisions of this Article or of this Act, or otherwise were guilty of a knowing breach of their duties as such under this Act.
10 ILCS 5/4-27