Forensic Analysis for Questioned Document Examination
Provide Evidence of Suspicious or Questionable Documents
Questioned document examination (QDE) is a forensic science discipline pertaining to documents that are potentially disputed in a court of law. The examination's primary purpose is to provide evidence about suspicious or questioned documents using a variety of scientific principles and methods depending on the type of document.
While this forensic discipline initially focused mostly on graphological, or handwriting analysis, the availability of advanced mass reproduction devices as well as modern microanalysis technologies extended this field. It now includes the examination of specific machine characteristics for illegally reproduced legal documents such as passports, driver IDs, academic and qualification certificates, birth certificates, voting ballots, any government-issued security documents and counterfeit currency. Photocopier and printer manufacturers typically implement (1) a counterfeit protection system (CPS) that can link two or more photocopied documents as having been produced by the same machine together with (2) machine identification codes (MIC) on each printed document to identify the specific make and model. In addition, government-issued security documents and currencies often feature a multitude of safety features embedded in the special security paper including but not limited to:
- holographic printing
- thermochromatic ink
- phosphorescent fibers
- and various other hard-to-reproduce safety characteristics
Forensic experts in QDE are familiar with these specific features and have access to a multitude of scientific analytical and imaging methods to identify counterfeited security documents and currencies.
As already stated above the “classic” key element of document examination focuses on graphological, or handwriting analysis. Typical documents would be last wills, contracts, cheques, provenance but also ransom notes or writings found at crime scenes.
Forensic examination and comparison of handwriting, which includes hand printing and signatures, is based on three main principles: (1) Given a sufficient amount of handwriting, no two skilled writers exhibit identical handwriting features; (2) every person has a range of natural variation to his or her writing; (3) no writer can exceed his or her skill level. Modern document analysis also includes chemical analysis of inks and papers as well as topographical measurements of imprints.
Equipment used in forensic document examination includes microscopes and additional optical aids; photographic and computer imaging devices, a wide variety of imaging materials adaptable for use with a variety of lighting methods, including those involving radiant energy in the ultraviolet, visible, infrared, and other regions of the electromagnetic spectrum; scanning electron microscopes with a wide range of topographical and analytical detection methods.