Transcript Footwear and Tire Track Evidence

Footwear Evidence
Summary
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What is footwear evidence?
How is it involved in crime scenes?
How is it collected?
How is it analyzed?
Footwear Evidence
What is footwear evidence?
Different shoes will leave behind prints of
different sizes and patterns.
Footwear Evidence
Three different types of shoe prints:
Three dimensional impression
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Shoeprint made in soft material (dirt, snow)
Requires making a cast of the print
Composition of dirt
or snow will
determine the detail
of the impression.
Footwear Evidence
Three different types of shoe prints:
Two dimensional print (visible)
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Dirt or other material picked up by shoe and
deposited onto flat, hard surface.
Variety of surfaces
and materials
deposited makes
recovery of these
prints complex.
Footwear Evidence
Three different types of shoe prints:
Two dimensional print (latent)
3.
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Can leave behind barely visible dust
Can leave impression in polish/wax/dust
Footwear Evidence
Three different types of shoe prints:
Two dimensional print (latent)
3.
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Can leave behind barely visible dust
Can leave impression in polish/wax/dust
Footwear Evidence
How are shoe prints evidence?
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Most suspects wear shoes.
Footprints are always left, it is whether
they can be located and differentiated
from other prints.
Burglar
Shoes
Footwear Evidence
What information can shoe prints provide?
Link suspect or victim to scenes
Link two crime scenes
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Location of prints can:
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Lead to more evidence
Refute alibis
Gait or Tracking information?
Footwear Evidence > Collection
Recovery of Footwear evidence
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Due to numerous nuances, all
shoeprints should be recovered from
the scene.
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Scene should be controlled to prevent
destruction of evidence.
Footwear Evidence > Collection
Recovery of Footwear evidence
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Some prints can be visualized by
darkening a room and using a bright
light at a low angle.
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Footprints should be documented:
Location recorded and photographed
Footwear Evidence > Collection
Recovery of Footwear evidence
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Objects with footprints should be
removed if possible (paper, glass)
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If can’t be removed, an examination
quality photo should be taken.
Ruler: allows for enlargement to real size
Footwear Evidence > Collection
After photo, 2-D print can be lifted:
Electrostatic Lifting:
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A charge is used to lift dry
materials from surface to
black film.
Lift provides more contrast
Non-destructive
Photographed for evidence
Footwear Evidence > Collection
After photo, 2-D print can be lifted:
Dusting:
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Fingerprint powder can visualize print
Lifted with adhesive or gelatin
Photographed for evidence
Footwear Evidence > Collection
3-D impression can be highlighted
Spraying with colored wax spray
Footwear Evidence > Collection
3-D impression should be cast
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Cast picks up
detail; is durable
Cast after photo
Use dental stone
Footwear Evidence > Collection
Enhancement Methods
If footprint is made of blood, TMB or other
color changing reagents can help visualize.
Footwear Evidence > Analysis
Analysis of Footwear Evidence:
Class Characteristics can be used to
eliminate a suspected shoe or suggest a
shoe could have made the impression.
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Size
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Pattern
Suspect shoe or test impressions compared.
Footwear Evidence > Analysis
Analysis of Footwear Evidence:
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Individual Characteristics can be used to
identify an exact shoe.
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However, these can change over time.