65 ILCS 5/9-2-23
The superintendent of special assessments, or president of the board of local improvements, as the case may be, shall file with the commissioners' report an affidavit made by himself or by some employee of his office, that (1) the affiant has carefully examined the records in the recorder's office of the specified county or counties for the names of the owners of record of the several lots, blocks, tracts, and parcels of land to be taken or damaged for the improvement, (2) that the affiant made a careful examination of the collector's books showing the payments of general taxes during the last preceding year in which taxes were paid on the respective lots, blocks, tracts, and parcels of land against which benefits are assessed in the commissioners' report, to ascertain the person or persons who last paid the taxes on those respective lots, blocks, tracts, and parcels of land, (3) that the names of those owners of record and persons who paid those taxes are correctly shown in the columns or schedules of ownership and of persons who paid those taxes in the commissioners' report, (4) that he has diligently inquired as to the residence of the respective owners of property to be taken or damaged for the improvement and of the persons who paid the general taxes during the last preceding calendar year in which general taxes were paid on all the respective lots, blocks, tracts, and parcels of land against which benefits have been assessed in the commissioners' report (specifying the nature of the inquiry and examination he has made for that purpose), (5) that the residences of the owners and parties paying those general taxes are correctly stated, according to the result of his examination, in the column or schedule of residences in the commissioners' report, and (6) that in all cases where he has been unable to find the residence of the owner of the record title, he has examined the return of the collector's warrant for taxes on real estate for the last preceding year, in which the taxes were paid, and has set opposite each such parcel whose owner has not been found, the name of the person who last paid the tax on that parcel, together with his place of residence, wherever, on diligent inquiry, he was able to find the same. This affidavit, or an affidavit filed therewith, shall further state that the affiant has visited each of the parcels of land to be taken or damaged for the improvement described in the commissioners' report, for the purpose of ascertaining whether or not the parcel was occupied, and the name and residence of the occupant, if any, and that in every case where those parcels of land were found to be occupied, upon such investigation, the name of the occupant is stated in the commissioners' report opposite that parcel, together with his residence, when ascertained. Such an affidavit and report shall be prima facie evidence that the requirements of this Division 2 have been complied with.
65 ILCS 5/9-2-23