735 ILCS 5/9-304: Notice to non-residents.

When it appears, by affidavit filed in the court where such proceeding is pending, that the defendant is a nonresident or has departed from this state, or on due inquiry cannot be found, or is concealed within this state, and the affiant states the place of residence of the defendant, if known, and if not known, that upon diligent inquiry he or she has not been able to ascertain the same, notice may be given as in attachment cases.