Forensic Science Questioned Documents
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Transcript of Forensic Science Questioned Documents
Forensic Science
Questioned Documents
Questioned DocumentsQuestioned Documents
Any object that contains handwritten or typewritten markings whose source or authenticity is in doubt is considered a question document.
Questioned DocumentsQuestioned Documents
These include:
LettersChecksDriver’s licenseContractsWillsPassportsLottery tickets
Questioned DocumentsQuestioned Documents
Questioned documents may also include writings or markings found on walls, windows, doors, etc.
Questioned DocumentsQuestioned DocumentsThe 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.
Handwriting ComparisonsHandwriting 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).
Palmer Method Zaner-Blosser Method
Handwriting Handwriting ComparisonsComparisons
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, andfinger dexterity are distinguish.
Handwriting ComparisonsHandwriting ComparisonsMargins, spacing, crowding, insertions,and alignment arepersonal habits.
Spelling, punctuation, phraseology, and
grammar individualize each writer.
A final conclusion of comparison betweentwo documents must be based on asufficient number of commoncharacteristics.
Handwriting ComparisonsHandwriting 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
Collection of Handwriting Collection of Handwriting ExemplarsExemplars
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
Collection of Handwriting Collection of Handwriting ExemplarsExemplars
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 writingWriting of dictationAllow the writer to sit comfortablyFurnished with pen and paper similar to the questioned documentGive no instructions on grammar or punctuation
There are several mechanical devices and machines a document examiner encounters
Computers TypewritersTypewriter ribbonPhotocopiersPrintersFax machines
Typescript comparisonsTypescript comparisons
Alterations, Erasures, and Alterations, Erasures, and ObliterationsObliterations
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.
Alterations, Erasures, and Alterations, Erasures, and ObliterationsObliterations
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 sensitivefilm.
Infrared luminescencecan also reveal writing that has been erased.
Infrared Luminescence Infrared Luminescence examplesexamples
Alterations, Erasures, and Alterations, Erasures, and ObliterationsObliterations
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 sometimesBe revealed through infrared photography.
Other Document ProblemsOther 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 thedocument againstthe light.
Other Document ProblemsOther Document Problems
Electrostatic charge can beapplied to the surface if theindented document, thenlayered with toner powder to produce an image.
Other Document ProblemsOther 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
Other Document ProblemsOther Document Problems
The paper on which thedocument is written orprinted on is alsoanalyzed by the examiner.
Handwriting sample of George W. Bush
Other Document ProblemsOther Document Problems
Paper can vary by
Appearance ColorWeight
Watermarks
True watermark Fake watermark
Other Document ProblemsOther Document ProblemsPaper examined under a microscope can reveal:
Fibers Fillers
Pigments Additives
Non-coated Coated
Handwriting Handwriting IdentificationIdentification
“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.