Document Examination

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Document Examination

• Methods for Analyzing
• Questioned Documents

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Macroscopic Techniques

• Reflected Light observation of a document under
  normal lighting.
• May reveal incorrect paper, incorrect pen, or
  format errors
• Oblique-light (side light or grazing light)
• Reveals shadows from erasures, indentations, and
  embossments
• Transmitted light Use of a light box
• Identify type of paper and watermarks
• Detect erasures (thin spots in paper)

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Microscopic Techniques

• Stereoscope with 10-30 power is most useful for
  document examination
• Determine type of pen used
• Detect retouching, pen lifts, tremor, erasures,
  corrections

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Spectral Techniques

• Ultraviolet light
• Fluorescence
• Detect erasures and corrections
• Enhance faint writing
• Dissimilar glues or wax tampering on envelopes
• Infrared light (viewed by special means)
• Detect undersketching in art
• Decipher charred documents
• Differentiate inks (some absorb, while others
  reflect IR light)

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• Laser techniques
• Discriminate between similar inks
• Photographic techniques
• UV, IR, and laser photography
• Chromatography (thin layer or paper)
• Ink from document is analyzed along with
  reference (suspected) ink samples
• Inks are placed on thin layer of silica gel (or
  paper), which is then placed into a solvent.
• The solvent moves up the gel or paper by
  capillary action, separating inks as it moves.

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• Chromatography is based on polarity. The gel or
  paper has a different polarity than the solvent.
• Parts of the ink that are more like the gel or
  paper will not move, while those that are more
  like the solvent will travel up the
  chromatogram.
• Samples that produce similar chromatograms are
  likely to be the same ink.