Document & Voice Examination
Sunday, June 15, 2025
2:24 PM
Introduction
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Any object with handwriting or print whose source/authenticity is in doubt =
questioned document
Document examiners apply knowledge gathered through years of training & experience
to recognize & compare the individual characteristics of questioned & known authentic
writings
Gathering known documents is critical to examination
Uniqueness of handwriting makes this type of evidence one of few definitive individual
characteristics available
Character of Handwriting
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Document experts continually testify to fact no two individuals write exactly alike
Many factors comprise total character of writing
o Early stages of learning handwriting are characterized by conscious effort to copy
standard letter forms
o As skills improve, nerve and motor responses assoc w writing become
subconscious
o Unconscious handwriting of two individuals can never be identical
o Variations expected in angularity, slope, speed, pressure, spacing, relative
dimensions of letter, connections, pen movement, writing skill & finger dexterity
o Other factors to consider include arrangement of writing on paper such as
margins, spacing, crowding, insertions, alignment
o Writing style may be altered beyond recognition by influence of drugs/alcohol
No single characteristic can be taken as basis for positive comparison
Final conclusion must be based on sufficient number of common characteristics
between known and questioned samples
No rules for sufficient minimum, judgement made by examiner in context of case
Handwriting Exemplars
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Collection of adequate number of exemplars (known writings) is most critical for
determining outcome of comparison
Known writing should contain some words and combos of letters present in QD and
adequate in number to show range of variations
Writing tool and paper should be alike
Writing of dictation and several pages may minimize attempts at deception
Typewriters & Printing Devices
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Two requests most often made of examiner with examination of typewriters/printers:
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Whether the make and model of the typewriter and printing devices used to
prepare the QD can be identified
o Whether a particular suspect typewriter/printer can be ID'd as having prepared
the QD
 To do this, individual character style, shape, and size compared to complete reference
collection of past & present typefaces
Characteristics From Use:
 Use of a printer will result in wear and damage to machine's moving parts
 Changes will occur in random & irregular fashion, imparting indiv characteristics
 Document examiner has to deal with problems involving business and personal
computers, which often produce typed copies with only subtle defects
 Another area of investigations relates to typewriter ribbon, may contain type
impressions
Digital Technology
 Examiner may be called to ID make and model of machine (photocopiers, fax machines,
computer printers) or compare QD with samples from suspect machine
 Side-by-side comparison made between exemplars and QD to compare markings
 Examiners compare:
o Transitory defect marks
o Fax machine headers
o Toner
o Toner application methods
o Mechanical and printing characteristics
Alterations
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Examiners must deal with evidence that has been changed in several ways; erasures,
alterations, obliterations
Rubber erasures, sandpaper, razor/knife to remove writing/typing disturb paper fibers
and easily seen under microscope
If alteration made with different ink than original, sometimes can be detected due to
different properties of ink's luminescence
Obliteration of writing by overwriting or crossing out can be revealed by IR radiation
o Passes through upper layer of writing while being absorbed by underlying area
Digital image processing is method by which visual quality of pictures is
enhanced/improved
Digitizing is process by which image is stored into memory
Image can be scanned and computerized into array of digital intensity values called
pixels
Once image digitized, image editing program can be used to make adjustments
(lightening, darkening, color, contrast)
Using photo editor on digitized image can reveal info that has been obscured
Other Problems
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IR photography and reflecting light at different angles are sometimes used to reveal
contents of document that has been charred (accidentally or purposely) in a fire
Indented writings-partially visible depressions underneath the visible writing-have
proven to be valuable
o May be possible to determine what was written by impressions left on paper pad
o Applying electrostatic charge to surface of polymer film placed on QD will
visualize indented writings
Study of chemical composition of ink used may verify whether or not known and
questioned documents were prepared by same pen
Paper itself may be analyzed
Voice Examination
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Human voice may prove to be valuable evidence for associating criminal with crime
Probability that any two individuals:
o Will have same size vocal cavities
o Will coordinate their articulators (lips, teeth, tongue, jaw muscles, etc)
o In a like manner is so small that human voice is a unique trait
The Sound Spectrograph
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Sound spectrograph is an instrument that converts speech into a visual graphic display
called spectrogram or voiceprint
Courts have been asked to accept its results as evidence of participation in a crime
Still conflicting opinions as to whether it is generally accepted enough in scientific
community to be admissible
Spectrum portrays 3 parameters of speech: time, frequency, relative intensity/volume
When sufficient similarity exists between questioned and known, positive conclusion is
justified that they are from same person
Recent introduction of computerized sound spectrograph simplifies work
Examiners apply bother aural and visual techniques when comparing
Can then classify recording into one of seven categories:
o Positive identification
o Probable identification
o Possible identificati9on
o Inconclusive
o Possible elimination
o Probable elimination
o Positive elimination