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Forensic Science Questioned Documents

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Presentation on theme: "Forensic Science Questioned Documents"— Presentation transcript:

1 Forensic Science Questioned Documents

2 Questioned Documents Any object that contains handwritten or typewritten markings whose source or authenticity is in doubt is considered a question document.

3 Questioned Documents These include: Letters Checks Driver’s license
Contracts Wills Passports Lottery tickets

4 Questioned Documents Questioned documents may also include writings or markings found on walls, windows, doors, etc.

5 Questioned Documents The document examiner must ascertain the authenticity or source of a document through handwriting examination and the use of microscopy, photography, chromatography to note any change or alterations. The examiner must be able to recognize erasures and overwriting in attempt to change the original meaning of a document. The examiner must be able to reconstruct charred or burned paper.

6 Handwriting Comparisons
Although no two individuals write exactly alike, there may be resemblances is their general style. As a student learns and practices their handwriting, they are making a conscious effort to copy a standard letter form. The two most widely used methods taught in nearly all fifty states in the U.S. are the Palmer method (1880) and the Zaner-Blosser method (1895).

7 Palmer Method Zaner-Blosser Method

8 Handwriting Comparisons
Unconscious handwriting of two different individuals can never be identical. Several factors, such as, mechanical, physical, and mental functions, make reproduction of another’s handwriting unlikely. Variations of angularity, slope, speed, pressure, letter and word spacing, relative dimensions, connections, pen movement, writing skill, and finger dexterity are distinguish.

9 Handwriting Comparisons
Margins, spacing, crowding, insertions, and alignment are personal habits. Spelling, punctuation, phraseology, and grammar individualize each writer. A final conclusion of comparison between two documents must be based on a sufficient number of common characteristics.

10 Handwriting Comparisons
Circumstances may prevent a positive conclusion: Insufficient number of known handwriting samples are available Questioned writing may contain only a few words, deliberately written in disguise Drugs and alcohol can alter writing habits

11 Collection of Handwriting Exemplars
In gathering known writing samples for comparison, or exemplars: Known writing should resembled the questioned document Should contain some of the words and combinations of letters present Give the range of natural variations Should be fairly recent, usually within 2-3 years

12 Collection of Handwriting Exemplars
When handwriting exemplars can not be obtained for comparison, a voluntary submittal from the suspect is requested. To help minimize attempts at deception, investigators can: Require several pages of writing Writing of dictation Allow the writer to sit comfortably Furnished with pen and paper similar to the questioned document Give no instructions on grammar or punctuation

13 Typescript comparisons
There are several mechanical devices and machines a document examiner encounters Computers Typewriters Typewriter ribbon Photocopiers Printers Fax machines

14 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.

15 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.

16 Infrared Luminescence examples

17 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.

18 Other Document Problems
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.

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

20 Other Document Problems
An examiner may also compare the chemical composition of the ink present in both documents using thin-layer chromatography. Using a hypodermic blunt tip needle, ink can be extracted and analyzed. Usually 10 plugs are sufficient. Two samples of black ink from two different manufacturers run using paper chromatography

21 Other Document Problems
The paper on which the document is written or printed on is also analyzed by the examiner. Handwriting sample of George W. Bush

22 Other Document Problems
Paper can vary by Appearance Color Weight Watermarks True watermark Fake watermark

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

24 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.

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