Sequencing the intersections of printed strokes with writing instrument strokes using DocuCentre expert (PIA 6000-EDF).

Introduction of the digital techniques in document examination has encouraged the Forensic Document Examiners to work with better accuracy in non-destructive ways. In this study, the examination of sequence of intersecting strokes of printers (inkjet printer, laser printer, dot-matrix printer) and typewriters with writing instruments (gel ink pen, ballpoint pen and fountain pen) of different colors was carried out by using Docucenter Expert via PIA-6000 software utilizing extended depth of focus. The continuity of the stroke is the only characteristic which has been observed at the point of intersection.

Application of Video Spectral Comparator (absorption spectra) for establishing the chronological order of intersecting printed strokes and writing pen strokes.

The sequence of intersecting strokes of laser printers (black, blue, red and green) and typewriter ink (black) with the strokes of gel pen ink, ballpoint pen ink and fountain pen ink (black, blue, red and green) has been determined by studying their absorption spectra. The absorption spectra have been generated for each of the two pure inks (i.e. A and B) and points of their intersections (i.e. A over B and B over A) by using Video Spectral Comparator (VSC-2000-HR). The study was carried out with an assumption that the peak characteristics of spectra from the point of intersection should correspond to the peak characteristics of pure ink which was executed later. It was observed that the absorption spectrum of intersection corresponds with either the laser printer or the typewriter ink stroke, whether these strokes were executed earlier or later than the writing instrument strokes. As the results obtained from the study were negative, the FDEs are advised against the practice of this technique in the examination of the sequence of intersecting strokes for these specified inks.

Determining the sequence of intersecting gel pen and laser printed strokes--a comparative study.

The relative chronological sequence of intersecting gel pen ink lines and laser printed marks has been determined using optical methods. The results were obtained by observing spectral reflection, relative sheen, skipping and gaps of gel pen ink strokes at the point of intersection. The intersections are observed under stereomicroscope and digital microscope. The effectiveness of both the optical instruments for sequence of the strokes has been compared. The sequence of intersecting lines (of same colour, different colours and where one of the strokes is darker) has been established.

A study for establishing the sequence of superimposed lines: inkjet versus writing instruments.

Intersections of inkjet strokes of different color (black, red, green and blue) with ballpoint ink or gel pen ink or fountain pen ink strokes each of different color (black, red, green and blue) were examined under stereomicroscope and digital microscope. The exemplars (25,920 intersections) were prepared on three types of paper at three time intervals. Stereomicroscope proves very successful in determining the sequence of ballpoint ink or gel pen ink of different color and inkjet stroke of black color only. It also helps in determining the sequence of intersections of fountain ink strokes (all color) and inkjet strokes (all color) with highest success rate (100% correctness). The digital microscope is not useful in determining the order of inkjet strokes and ballpoint ink or gel pen ink. These observations show that for the correct order of sequence, intersections magnification as well as good angle of illumination is required.