Application of physical techniques for establishment of homogeneous and heterogeneous intersecting strokes between laser toner and writing pen inks

In questioned document examination, establishing the sequence of crossing lines has always been a complex task for a forensic document examiner. This study aims to determine the sequence of homogeneous and heterogeneous crossing lines prepared by using laser printer and writing pen inks (ballpoint and gel pens) through optical methods. The samples were examined under stereomicroscope and LED microscope. The outcomes were based on examination of intersection under LED microscope and stereomicroscope. It was observed that stereomicroscope gave 100% accurate results in establishing the sequence of crossing lines of laser printer and writing pen inks (of same and different colours). Under LED microscope, the only feature observed was compression of laser toner stroke by ballpoint and gel pen ink lines.