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Articles  »  Document Examination

How Valuable is Handwriting in an Investigation? (The Science of H andwriting)

Handwriting is an important aspect of an investigation in forensic science. As with many aspects of the science, handwriting can serve amazing purposes. Just a sample of someone's signature can say many things. Every person has unique handwriting, and everyone's handwriting changes over time. A signature from ten years ago will be different from one today. This fact can be used to fix the date of a document or a forgery. If someone suspects that a document was forged, the date that it was signed may not match the appearance of the signature at that particular time, especially if the forger took the sample from an earlier year. Handwriting comparison can include factors such as height ratios, slant, proportions, pressure, speed and line quality. Infrared light is used to analyze some aspects of a sample of writing. If one pen was used to write something, and another was used to change the information, they can be separated using this technique, as different inks will be made from different chemicals and have different properties. Infrared examination may involve using special light filters and films for photographic imaging, or by using a machine designed for Video Spectral Comparison (VSC). Thin Layer Chromatography (TLC) is another scientific way to tell whether a piece of document has been forged or not. However, the infrared light method is the more reliable.  

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Warner, Erica. Forensic Science. New York: Houghton Mifflin, 1997.