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Computer Analysis

Computer Analysis. 15. Linguist. Experts that look at the linguistic content (the way something is written) of a questioned document. Language that is used can help to establish the writer’s age, gender, ethnicity, level of education, professional training, and ideology.

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Computer Analysis

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  1. Computer Analysis

  2. 15. Linguist Experts that look at the linguistic content (the way something is written) of a questioned document. Language that is used can help to establish the writer’s age, gender, ethnicity, level of education, professional training, and ideology.

  3. 20. Typescript Comparisons There are several mechanical devices and machines a document examiner encounters Computers Typewriters Typewriter ribbon Photocopiers Printers Fax machines

  4. 16. & 17. Document Alterations • Obliterations—removal of writing by physical or chemical means can be detected by: • Microscopic examination • UV or infrared (IR) light • Digital image processing • Indentations can be detected by: • Oblique lighting • Electrostatic detection apparatus (ESDA)

  5. Alterations, Erasures, and Obliterations The most common way to alter a document is erasure, either using an Indian rubber erasure, or with chemicals. These changes can be seen under a microscope using direct or side lighting.

  6. 19. 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.

  7. Infrared Luminescence examples

  8. Alterations, Erasures, and Obliterations 16. 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.

  9. 17. 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.

  10. 18. Other Document Problems Electrostatic charge can be applied to the surface if the indented document, then layered with toner powder to produce an image.

  11. 9. 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

  12. Retention Factor (Rf) • This is a number that represents how far a compound travels in a particular solvent • It is determined by measuring the distance the compound traveled and dividing it by the distance the solvent traveled.

  13. Specialized Ligthing

  14. Paper The paper on which the document is written or printed on is also analyzed by the examiner. Handwriting sample of George W. Bush

  15. 13. & 14. Paper Differences • Raw material • Weight • Density • Thickness • Color • Watermarks • Age • Fluorescence True Watermark Forged Watermark

  16. 13. Other Document Problems Paper examined under a microscope can reveal: Fibers Fillers Pigments Additives Non-coated Coated

  17. Pencils • Lead • Hardness Scale—a traditional measure of the hardness of the "leads" (actually made of graphite) in pencils. The hardness scale, from softer to harder, takes the form ..., 3B, 2B, B, HB, F, H, 2H, 3H, 4H, ..., with the standard "number 2" pencil being of hardness 2H.

  18. Codes and Ciphers • Codes--letter combinations or symbols used to represent words or concepts • Interception from terrorists and other war enemies • Ciphers--a message in which letters or symbols replace the actual letters in the message.

  19. 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.

  20. Handwriting Identification • “ACE” • Analysis of the “knowns” with a determination of the characteristics found in the known • Analysis of the questioned or unknown writing and determination of its characteristics • Comparison of the questioned writing with the known writing. • Evaluation of the evidence, including the similarities and dissimilarities between the “questioned” and “known” writing.

  21. CRAZY CRIMINALS According to Point of View, a magazine published by the Alameda county District Attorney’s office, a guy walked into an Oakland bank and handed the teller a note reading, “this is a stikkup. Hand over all yer money fast.” Guessing from this that the guy was no rocket scientist, the teller replied, “I’ll hand over the cash as long as you sign for it. It’s a bank policy that all robbers have to sign for their money.” The guy thought this over, then said “Uh, I guess that’s OK.” He signed his full name and address. That’s where the cops found him a few hours later.

  22. More aboutDocument 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

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