Forensic Footwear Evidence

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Forensic Footwear Evidence
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Two Types of Footwear Impressions

• 1. Three Dimensional
• 2. Two Dimensional

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Three Dimensional Impressions

• Those that remain after a shoe has permanently
  deformed a surface.
• Usually found on exterior surfaces like sand,
  soil or snow

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Two Dimensional Impressions

• Impressions made on non-giving surfaces like
  tile, linoleum or wood floor, paper, plastics,
  doors, carpet, clothing, counter tops, etc
• May be highly visible or latent

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Information From Footwear Impressions

• Identification of footwear
• Elimination of footwear
• Participation in the crime
• Location of impressions
• Rebuttal or confirmation of suspects alibis
• Determination of shoe brand
• FBI shoe design data base

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Information From Footwear Impressions

• Linking scenes of crime (burglaries)
• Determination of shoe size
• Number or perpetrators
• Association of other evidence (follow impressions
  to other evidence)
• Gait characteristics
• Tracking

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Tracking

• Used mostly for tracking illegal aliens and
  missing children
• Most trackers in the United States are in the
  U.S. Border Patrol

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Lifting Two Dimensional Impressions

• Two Methods
• 1. Electrostatic method
• 2. Fingerprint powder

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Lifting Two Dimensional Impressions

• Electrostatic method-
• High voltage power source to create a static
  electrical charge that enables the transfer of a
  dry origin impression from the surface to a
  special black lifting film

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Lifting Two Dimensional Impressions

• Fingerprint powder-
• Can enhance and visualize the impression
• If it does, photograph and then lift with a
  gelatin or adhesive lifter
• Mikrosil is a silicone product that can be used
  to lift powdered footwear impressions from any
  surface

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Lifting Three Dimensional Impressions

• Dental Stone-
• Harder with higher compressive strength than
  plaster
• Quicker and easier than plaster

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Class Characteristics of Footwear

• Design
• Physical Size and Shape
• Wear
• Individual Identifying Characteristics

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Class Characteristics of Footwear

• Design
• The most obvious class characteristic
• First step in matching to a suspect shoe
• If design corresponds with suspect, examination
  continues

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Class Characteristics of Footwear

• Physical Size and Shape
• Actual shoe size
• When crime scene impression corresponds in both
  design and physical size of suspects shoe, then
  has high evidentiary value

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Class Characteristics of Footwear

• Wear
• As wear progresses, noticeable differences occur
  between areas of higher wear or of less wear and
  develop a pattern
• Assess the Position of wear and the Degree of
  wear

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Class Characteristics of Footwear

• Individual Identifying Characteristics
• Cuts, scratches, gouges, tears and other physical
  damage that occurs to the surface of the shoe
  sole
• Also tar, gum, nails, tacks and stones wedged
  between the design

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Class Characteristics of Footwear

• No minimum number of characteristics are
  necessary for a positive I.D.
• Usually two or more is all that is needed to I.D.
  a shoe with a crime scene impression
• A single characteristic can be all that is
  necessary if the characteristic is significant