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Chapter 16 DOCUMENT AND VOICE EXAMINATION

Chapter 16 DOCUMENT AND VOICE EXAMINATION. Introduction. Questioned document Handwriting or print Source or authenticity in doubt Document examiners Recognize and compare individual characteristics Questioned and known authentic writings

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Chapter 16 DOCUMENT AND VOICE EXAMINATION

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  1. Chapter 16DOCUMENT AND VOICE EXAMINATION

  2. Introduction • Questioned document • Handwriting or print • Source or authenticity in doubt • Document examiners • Recognize and compare individual characteristics • Questioned and known authentic writings • Gathering of documents of known authorship or origin critical • Uniqueness of handwriting • One of few definitive individual characteristics available DOCUMENT AND VOICE

  3. Handwriting Comparisons

  4. Character of Handwriting • No two individuals write exactly alike • Many factors comprise total character of a person’s writing • Early stages of learning handwriting • Conscious effort to copy standard letter forms • As writing skills improve • Nerve and motor responses associated with the act of writing become subconscious • Unconscious handwriting of two different individuals can never be identical DOCUMENT AND VOICE

  5. Character of Handwriting • Variations are expected • Angularity • Slope • Speed • Pressure • Letter and word spacing • Relative dimensions of letters • Connections • Pen movement • Writing skill • Finger dexterity DOCUMENT AND VOICE

  6. Character of Handwriting • Other factors to consider • Arrangement of writing on paper • Margins • Spacing • Crowding • Insertions • Alignment. DOCUMENT AND VOICE

  7. Character of Handwriting • Other factors to consider • Spelling • Punctuation • Phraseology • Grammar • Influence of drugs or alcohol • Writing style of may be altered beyond recognition DOCUMENT AND VOICE

  8. Character of Handwriting • No single handwriting characteristic • Can taken as the basis for a positive comparison • Final conclusion must be based on • “Sufficient number” of common characteristics • Between the known and questioned writing samples • No hard and fast rules for “sufficient number” of personal characteristics • Judgment call made by the expert examiner in the context of each case DOCUMENT AND VOICE

  9. Collection of Handwriting Exemplars

  10. Handwriting Exemplars • Collection of an adequate number of known writings (exemplars) • Known writing should contain • Some of words and combination of letters present in the questioned document • Adequate in number to show range of natural variations in suspect’s writing • Writing implement and paper should also be alike • Writing of dictation, several pages minimizes attempts at deception DOCUMENT AND VOICE

  11. Supreme Court Rulings • Gilbert v. California • Upheld taking exemplars for counsel appointed • Physical characteristics the lie outside 5th amendment protection • United States v. Mara • Taking sample did not constitute unreasonable search & seizure of person • Did not violate 4th amendment rights

  12. Other Steps to Avoid ConsciousAlteration of Writing during Dictation • Sit comfortably without distraction • Should not see questioned document • Should not be given spelling or punctuation hints • Use pen and paper similar to document • Dictate same contents or words, phrases, letter combinations in text • Should not be told to use upper/lower case in printing samples

  13. Other Steps to Avoid ConsciousAlteration of Writing during Dictation • Three different dictation to point out variations if disguising writing • Signatures combined with other writing such as checks, forms, etc. • Examiner consulted prior to taking samples

  14. Typescript Comparisons

  15. Typewriters and Printing Devices • Two requests of examiner • Make and model of the typewriter and printing devices used to prepare the questioned document identified • Suspect typewriter or printing device identified as having prepared the questioned document • Individual type character’s style, shape, and size compared to complete reference collection of past and present typefaces DOCUMENT AND VOICE

  16. Characteristics From Use • Wear and damage to the machine’s moving parts • Random and irregular • Individual characteristics to the printing device • Business and personal computers • Typed copies with subtle defects • Typewriter ribbon • May contain type impressions DOCUMENT AND VOICE

  17. Missing Suspect Typewriter? • Gather known writings typed on machine • Same combinations of letters and word in suspect document • Use most recently prepared documents from collection

  18. Photocopier, Printer and Fax Examination

  19. Digital Technology • Role of examiner • Identify the make and model of a machine • Compare a questioned document with test samples from a suspect machine • Side-by-side comparison • The questioned document and the printed exemplars • Compare markings produced by the machine DOCUMENT AND VOICE

  20. Digital Technology Comparisons • Transitory defect marks (debris on glass, etc.) • Fax machine headers • Transmitting terminal identifier (TTI) • Different type style from document • Database comparison: American Society of Questioned Document Examiners DOCUMENT AND VOICE

  21. Digital Technology Comparisons • Toner • Type of toner or ink • Surface morphology • Chemical composition: inorganic and organic constitutents DOCUMENT AND VOICE

  22. Digital Technology Comparisons • Toner application methods • Impact: thermal, dot matrix • Non-impact: ink jet, laser • Mechanical and printing characteristics • Paper DOCUMENT AND VOICE

  23. Alterations, Erasures, and Obliterations

  24. Alterations • Hide original intent of document • Perpetrate forgery DOCUMENT AND VOICE

  25. Alterations: Erasures • Mechanisms • Rubber erasers • Sandpaper • Razor blade • Knife • Disturbs fibers of the paper • Readily apparent when examined with a microscope • Alteration with ink differing from the original • Detected due to differences in luminescence properties of the inks DOCUMENT AND VOICE

  26. Alterations: Chemical Erasures • Strong oxidizing agent • Removes color • Alteration not apparent in room light • Microscopic exam: discoloration • UV/IR: fluorescent ink • IR Luminescence • Blue-green light • Infra-red sensitive flim • Erasures: invisible ink residue • Differentiate inks DOCUMENT AND VOICE

  27. Alterations: Obliteration • Overwriting or crossing out • Hides the original writing • Revealed by infrared radiation • May pass through the upper layer of writing • Absorbed by the underlying area • Also revealed by microscopy • Crossing strokes • Strokes across folds, perforations • Not consistent with normal document preparation DOCUMENT AND VOICE

  28. Alterations: Obliteration • Digital image processing • Charred documents • Scan • Adjust image • Contrast • Lightening • Darkening • Color • Digitized image can reveal obscured information DOCUMENT AND VOICE

  29. Other Document Problems DOCUMENT AND VOICE

  30. Other Problems • Infrared photography and reflecting light at different angles • Reveal the contents of a document accidentally or purposely charred in a fire • Indented writings • Partially visible depressions underneath the visible writing • Impressions left on a paper pad DOCUMENT AND VOICE

  31. Other Problems • London College of Printing • Metropolitan Police Forensic Science Laboratory • Apply electrostatic charge to surface of a polymer film placed in contact with questioned document • Visualize indented writings DOCUMENT AND VOICE

  32. Other Problems • Composition of ink • Nondestructive testing • Visible microspectrophotometer • Known and questioned documents were prepared by the same pen • Paper chromatography • Thin layer chromatography • FTIR • Remove from paper with micro-paper punch (10 samples) DOCUMENT AND VOICE

  33. Other Problems • Paper analysis • Source of cellulose fibers • Wood • Recycled paper products • Common features • Color • Weight • Watermarks • Also • Additives • Fillers • Pigments DOCUMENT AND VOICE

  34. Voice Examination

  35. Voice Examination • Valuable evidence for associating individual with a criminal act • Bomb threats • Obscene phone calls • Kidnap ransom requests • Relatively common DOCUMENT AND VOICE

  36. Voice Examination

  37. Voice Examination • Probability that any two individuals: • Will have the same size vocal cavities • (throat, nasal, and two oral cavities formed by positioning the tongue) • Will coordinate their articulators • (lips, teeth, tongue, soft palate, and jaw muscles) • So small as to make human voice a unique personal trait DOCUMENT AND VOICE

  38. Sound Spectrograph

  39. The Sound Spectrograph • Invented at Bell Labs in 1941 • Lawrence Kersta (system engineer) • WWII intellegence • German voice transmissions • Post war: unique personal identification DOCUMENT AND VOICE

  40. The Sound Spectrograph • Converts speech into a visual graphic display: Spectrogram or Voiceprint • Courts asked to accept its results as evidence of an individual’s participation in a crime • Still conflicting opinions in the courts as to whether the voiceprint • “general acceptance” ? • Admissibility as scientific evidence? DOCUMENT AND VOICE

  41. The Sound Spectrograph • Report to National Academy of Science • Accuracy and error rate • Vary from case to case • Depend on • Conditions when taken • Properties of voices • Equipment used • Skill of examiner • Examiner knowledge of case

  42. The Sound Spectrograph • No adequate evidence for reliability • 34.8 % (2000 cases) meaningful decisions • 0.31% error rate for false indentification • 0.53% error rate for false eliminations

  43. The Sound Spectrograph • Three parameters of speech • Time • Frequency • Relative intensity or volume • Sufficient similarity between questioned and known voice  positive conclusion justified that both voices from the same person • Recent introduction of computerized sound spectrograph DOCUMENT AND VOICE

  44. The Sound Spectrograph • Seven categories of comparisons • Positive identification (more than 20 matching sounds) • Probable identification (more than 15 matching sounds, no unexplained differences • Possible identification (more than 10 matching sounds, no unexplained differences) • Inconclusive (poor recording) • Possible elimination (10 or more sounds do not match) • Probable elimination (15 or more sounds do not match) • Positive elimination (20 or more sounds do not match) DOCUMENT AND VOICE

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