Forensic importance and advancements in microscopic examination of questioned documents

Questioned document examination is one of the most challenging tasks in the field of forensic science. Examining the document without destroying its integrity is difficult in such cases. Microscopic examination is a noble and mostly non-destructive approach in document examination. It enables the examiner to visualize the evidence in the document, which would have been otherwise difficult with unaided eyes. The purpose of the study was to establish the importance of microscopic examination in document examination. A critical review of 60 years, from 1963 to 2023, of various research papers from different journals has been conducted. Applications of various microscopes including stereo microscopes, digital microscopes, scanning electron microscopes (SEM), and atomic force microscopes (AFM) were reviewed. Compared to the basic examinations performed before the year 2000, there was a remarkable evolution involving complex examinations with more precise results after the year 2000. Microscopy helped solve almost all kinds of problems involved in document examination. Among all microscopes, the stereo microscope was found to be a prominent tool in document laboratories. Certain limitations were also listed for microscopic examination over spectroscopic methods. However, microscopes have been the tool of choice for forensic document examiners.