NCJ Number
196289
Journal
Law Enforcement Technology Volume: 29 Issue: 7 Dated: July 2002 Pages: 72,74-77,80,81
Date Published
July 2002
Length
7 pages
Annotation
This article describes a machine called an Electrostatic Detection Apparatus (ESDA), which reveals indentations invisible to the naked eye.
Abstract
The ESDA machine, manufactured by Foster & Freeman Ltd. of the United Kingdom, is the size of a desktop copying machine. The blank page is covered with a cellophane material and is subjected to a repeated high voltage static charge. Black toner is cascaded over the cellophane surface. This technique is extremely sensitive and clearly reveals indented writing on a blank writing pad. The rule is to always investigate questioned documents before using a latent fingerprint test. If the pad had been processed for fingerprints, ESDA would not be able to retrieve the indented writing. A simple hold-up note can be a crucial piece of evidence that will solve the case. Crime scene investigators should always safeguard pertinent documentary evidence and if possible, make photocopies. Forensic document examination helps police departments and Federal law enforcement agencies investigate a wide range of crimes that involve typewriting, checkwriter and rubber stamp impressions, watermarks, commercial printing, photocopies, papers, inks, and any other documentary evidence. The role of the document examiner is to objectively interpret the evidence. The purpose of the examination is to find out who is responsible for generating the questioned document. There are only about 300 accredited examiners in the country. Document examiners can sometimes successfully identify questioned typewriting with the typewriter that produced it. Cases that stretch back many years can sometimes be solved through examining dusty, old documents. The Video Spectral Comparator, known as the VSC2000, exposes a document to a wide range of light sources and filters from various wavelengths of the light spectrum, including infrared and ultraviolet light. This process makes it possible to discern faint notations that are invisible to the human eye, as well as reveal alterations or obliterations on a document. A document examiner must stay up-to-date with the many different kinds of printing processes that are on the market today, such as personal computers and laser printers.