Examination of paper and toner in page insertion/substitution cases using TLC, GC-MS and FT-IR microspectroscopy

The comparison of paper and toner of each sheet (or certain pertinent pages) of a multi-page document produced with toner-based electrophotographic technology may help: (A) to determine if there have been page insertions or page substitutions; or (B) to test a hypothesis that multiple documents, which were supposed to come from different sources, have a common source. This article shows that a combination of three analytical methods, thin-layer chromatography (TLC), gas chromatography-mass spectrometry (GC-MS), and reflectance Fourier transform infrared (FT-IR) microspectroscopy, provides high discriminating power with regard to both paper and toners that cannot be distinguished by non-destructive (optical) techniques. These three analytical methods may allow the examiner to achieve a high level of certainty when evaluating which of two competing hypotheses is more probable:
• (Case A) the “prosecution” hypothesis, Hp, that certain pages in the document have been substituted, or the “defense” hypothesis, Hd, that no page substitution has occurred since the initial production of the document;
• (Case B) the “prosecution” hypothesis, Hp, that multiple documents, which were supposed to come from different sources, have a common source, or the “defense” hypothesis, Hd, that all the documents came from their respective origins as indicated on the documents.