Question Docs Part 2
Linguist Language that is used can help to establish the writer’s age, gender, ethnicity, level of education, professional training, and ideology. Unibomber Case
Typescript Comparisons There are several mechanical devices and machines a document examiner encounters Computers Typewriters Typewriter ribbon Photocopiers Printers Fax machines
Document Alterations Oblique lighting Obliterations—removal of writing detected by: Microscopic examination UV or infrared (IR) light Digital image processing Indentations can be detected by: Oblique lighting Electrostatic detection apparatus
Alterations, Erasures, and Obliterations Erasure, either using an Indian rubber erasure, or with chemicals. Changes can be seen using microscope or direct or side lighting.
Alterations, Erasures, and Obliterations Examiners often use Infrared Luminescence. When some inks are exposed to blue-green light, they absorb the radiation and reradiate infrared light, making any alterations visible with infrared sensitive film. Infrared luminescence can also reveal writing that has been erased.
Infrared Luminescence examples
Alterations, Erasures, and Obliterations Obliteration is the act of blotting or smearing over a writing or printing to make the original unreadable. The contents of a charred document can sometimes Be revealed through infrared photography.
Other Document Evidence Indented writings are the impressions left on papers positioned under a piece of paper that has been written on. Sometimes the document is readable with oblique lighting, or angling the document against the light.
Other Document Problems Electrostatic charge can be applied to the surface if the indented document, then layered with toner powder to produce an image.
Ink Chromatography--physically separates mixtures of gases, liquids or dissolved solids. Types Gas Chromatography HPLC--high-performance liquid chromatography TLC--thin-layer chromatography Paper Chromatography
Specialized Ligthing
Paper Differences Raw material Weight Density Thickness Color Watermarks Age Fluorescence True Watermark Forged Watermark
Other Document Problems Paper examined under a microscope can reveal: Fibers Fillers Pigments Additives Non-coated Coated
Evidence Class characteristics may include general types of pens, pencils or paper. Individual characteristics may include unique, individual handwriting characteristics; trash marks from copiers, or printer serial numbers.
More about Document Analysis For additional information about document and handwriting analysis, check out Court TV’s Crime Library at: lwww.crimelibrary.com/criminal_mind/forensics/literary/1.htm Or forgery cases at: www.crimelibrary.com/criminal_mind/scams/lincoln_forgers/index.html