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19  Forensic Science Powerpoint Chapter 19 Forensic Footwear Evi
 

19 Forensic Science Powerpoint Chapter 19 Forensic Footwear Evi

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    19  Forensic Science Powerpoint Chapter 19 Forensic Footwear Evi 19 Forensic Science Powerpoint Chapter 19 Forensic Footwear Evi Presentation Transcript

    • Forensic Science An Introduction to Scientific and Investigative Techniques Stuart H. James and Jon J. Nordby Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Chapter 19
      • Forensic Footwear Evidence
      • Chapter Author: William J. Bodziak
      • Presentation created by Greg Galardi, Peru, Nebraska
      • Edited by Stuart H. James, Fort Lauderdale, Florida and
      • Dan Mabel, Richmond, Virginia
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Forensic Footwear Evidence
      • Physical contact between footwear and a viable surface leaves a transfer of class and individual characteristics, which can be used in identification of possible suspects
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Forensic Footwear Evidence
      • Steps of footwear evidence collection:
        • Detection and recovery of footwear evidence from scene of crime
        • Enhancing evidence as necessary
        • Producing known impressions of shoes being examined
        • Comparing crime scene impression with footwear
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Forms of Footwear Impressions
      • Three Dimensional Impressions – impression remaining after a shoe permanently deforms a surface- found in sand, mud, snow
      • Two Dimensional impressions – those impressions made on tile linoleum, wood flooring etc. Some are highly visible and others are latent
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Information from Footwear Impressions
      • The following information may be obtained from footwear impressions:
        • Identification of Footwear
        • Elimination of Footwear
        • Participation of suspect in crime
        • Location of Impressions
        • Rebuttal or confirmation of alibis
        • Determination of shoe brand – FBI Laboratory
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Information from Footwear Impressions
      • Linking of Suspects to the Crime Scene
      • Determination of Shoe Size
      • Number of perpetrators
      • Association with Other Evidence
      • Gait Characteristics
      • Tracking
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Location and Recovery of Footwear Impressions
      • It is critical that proper techniques be used to locate, document and recover footwear evidence
      • Full and partial impressions must be recovered
      • Scene should be secured and evidence collected
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
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    • Location and Recovery of Footwear Impressions
      • Electrostatic Lifting – aggressive technique to recover impression, normally on tile, wood, etc
      • Placards or markers used to document locations of impressions
      • If possible, remove and transport impressions
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Location and Recovery of Footwear Impressions
      • Quality photographs should be taken of impressions if they can not be transported
      • Photographs are taken for later comparison with suspected footwear, therefore they must be very clear
      • Scale should be used to gauge size of footprint
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    •  
    • Two – Dimensional Impressions
      • Once an impression has been photographed, the print may be able to be lifted
      • Electrostatic lifting transfers
      • Fingerprint powder in combination with mikrosil may be used on impressions where electrostatic lifting does not work
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
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    • Three – Dimensional Impressions
      • Dental stone is primary method of casting footwear impressions
      • On wet surfaces, a spray wax may have to be used first to seal impression
      • Mix dental stone with water in a ziplock bag for 3 minutes
      • Stone hardens in 20 minutes
      • In 24-48 hours it will have fully hardened
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    •  
    • Enhancement Methods
      • Poor impressions may have to be enhanced by one of the following means:
        • Forensic Photography – oblique, ultraviolet, infrared or other special methods
        • Physical Methods – latent powder, lifting impressions, or impressions on paper
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Enhancement Methods
      • Chemical Methods – reagents such as leuco crystal violet, amido 10 black, luminol or fuschin acid may be used
      • Digital Methods – Software such as Adobe Photoshop can be used to enhance impressions
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
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    • Known Shoes and Preparation of Exemplars
      • Footwear from Suspected Persons:
        • All footwear a suspect owns should be seized for comparison
        • Shoes are needed to make test impressions
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    •  
    • Known Shoes and Preparation of Exemplars
      • Elimination Footwear – Footwear worn by police officers, medical personnel should be accounted for when considering impressions left at scene
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
    • Known Shoes and Preparation of Exemplars
      • Known Test Impressions of Footwear
        • Examiner will make impressions of known footwear and compare them with suspected footwear impression to insure matching samples are highly detailed, and have individual characteristics of shoes
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
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    • The Examination Process and Conclusions
      • Areas of footwear which are examined by analyst include:
        • Design of shoe
        • Physical Size and Shape
        • Wear marks
        • Individual Identifying Characteristics- cuts tar, gum etc
      Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition