750 ILCS 65/18

The petition shall be verified by the oath of the petitioner, and shall be filed in the office of the clerk of the circuit court. Notice of the filing of such petition shall be given to such person who is under disability, by service of summons or by publication, as provided in other civil cases. The court shall appoint some discreet person or attorney as guardian for the person alleged to be under disability, and the appointed person shall ascertain as to the propriety, good faith and necessity of the petition, and shall have power to resist such application and subpoena witnesses and take depositions to disprove any of the matters in the petition, or show the impropriety of granting the same.