Determination of the Sequence of Non-intersecting Stamp Impressions and Laser-Printed Document

Abstract

Questioned document examiners come across various documents to establish their originality, authorship and authenticity. With technological advancement, documents are printed using different printing devices, of which laser printers are highly commercialised. However, the misuse of such technological advancements has also increased, so laser printers can be used to create forged documents. One class of forged documents is built-up documents, which contain authentic signatures, but the contents of the document are added after appending the signatures. These documents might be printed using a laser printer, and stamp impressions may also be present, which do not intersect each other. Thus, to address such cases, the present study has been conducted to establish the sequence of production of a laser-printed document containing a stamp impression. A total of 720 samples were prepared, of which 360 samples were first printed and then stamped, and the rest of the samples were first stamped and then printed. For the analysis, a NIKON SMZ800N stereo microscope with a magnification of 2×10×8X was used. The technique was non-destructive, reliable and inexpensive. Variables such as the colour of the stamp, substrate (paper), and printouts from different laser printers were also studied to analyse their effect on the determination of the sequence of document production. Micro-conformation features of toner particles, fibre distribution, and ink distribution were analysed. The results obtained showed that the sequence of non-intersecting laser printing and stamping could be established using micro-conformation features of fibre distribution and ink distribution. However, the micro-conformation features of toner particles do not help in establishing the sequence. The study also highlights the precautions that must be taken while forming an opinion on the sequence of non-intersecting strokes.