815 ILCS 410/3
Any person, or agent or employee thereof, who sells a second-hand watch, shall deliver to the vendee a written invoice setting forth the name and address of the vendor, the name and address of the vendee, the date of the sale, the fact that the watch is second-hand, the name of the watch or its maker, and the serial numbers (if any), or other distinguishing numbers or identification marks on its case and movement. In the event the serial numbers or other distinguishing numbers or identification marks have been erased, defaced, removed, altered or covered, this shall be set forth in the invoice. A duplicate of the aforesaid invoice shall be kept on file by the vendor of such second-hand watch for at least one year from the date of the sale thereof and shall be open to inspection during all business hours by the State's attorney of the county in which the vendor is engaged in business.
815 ILCS 410/3