19 Forensic Science Powerpoint Chapter 19 Forensic Footwear Evi

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19 Forensic Science Powerpoint Chapter 19 Forensic Footwear Evi

  1. 1. 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
  2. 2. Chapter 19 <ul><li>Forensic Footwear Evidence </li></ul><ul><li>Chapter Author: William J. Bodziak </li></ul><ul><li>Presentation created by Greg Galardi, Peru, Nebraska </li></ul><ul><li>Edited by Stuart H. James, Fort Lauderdale, Florida and </li></ul><ul><li>Dan Mabel, Richmond, Virginia </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  3. 3. Forensic Footwear Evidence <ul><li>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 </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  4. 4. Forensic Footwear Evidence <ul><li>Steps of footwear evidence collection: </li></ul><ul><ul><li>Detection and recovery of footwear evidence from scene of crime </li></ul></ul><ul><ul><li>Enhancing evidence as necessary </li></ul></ul><ul><ul><li>Producing known impressions of shoes being examined </li></ul></ul><ul><ul><li>Comparing crime scene impression with footwear </li></ul></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  5. 5. Forms of Footwear Impressions <ul><li>Three Dimensional Impressions – impression remaining after a shoe permanently deforms a surface- found in sand, mud, snow </li></ul><ul><li>Two Dimensional impressions – those impressions made on tile linoleum, wood flooring etc. Some are highly visible and others are latent </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  6. 6. Information from Footwear Impressions <ul><li>The following information may be obtained from footwear impressions: </li></ul><ul><ul><li>Identification of Footwear </li></ul></ul><ul><ul><li>Elimination of Footwear </li></ul></ul><ul><ul><li>Participation of suspect in crime </li></ul></ul><ul><ul><li>Location of Impressions </li></ul></ul><ul><ul><li>Rebuttal or confirmation of alibis </li></ul></ul><ul><ul><li>Determination of shoe brand – FBI Laboratory </li></ul></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  7. 7. Information from Footwear Impressions <ul><li>Linking of Suspects to the Crime Scene </li></ul><ul><li>Determination of Shoe Size </li></ul><ul><li>Number of perpetrators </li></ul><ul><li>Association with Other Evidence </li></ul><ul><li>Gait Characteristics </li></ul><ul><li>Tracking </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  8. 8. Location and Recovery of Footwear Impressions <ul><li>It is critical that proper techniques be used to locate, document and recover footwear evidence </li></ul><ul><li>Full and partial impressions must be recovered </li></ul><ul><li>Scene should be secured and evidence collected </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  9. 12. Location and Recovery of Footwear Impressions <ul><li>Electrostatic Lifting – aggressive technique to recover impression, normally on tile, wood, etc </li></ul><ul><li>Placards or markers used to document locations of impressions </li></ul><ul><li>If possible, remove and transport impressions </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  10. 13. Location and Recovery of Footwear Impressions <ul><li>Quality photographs should be taken of impressions if they can not be transported </li></ul><ul><li>Photographs are taken for later comparison with suspected footwear, therefore they must be very clear </li></ul><ul><li>Scale should be used to gauge size of footprint </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  11. 15. Two – Dimensional Impressions <ul><li>Once an impression has been photographed, the print may be able to be lifted </li></ul><ul><li>Electrostatic lifting transfers </li></ul><ul><li>Fingerprint powder in combination with mikrosil may be used on impressions where electrostatic lifting does not work </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  12. 18. Three – Dimensional Impressions <ul><li>Dental stone is primary method of casting footwear impressions </li></ul><ul><li>On wet surfaces, a spray wax may have to be used first to seal impression </li></ul><ul><li>Mix dental stone with water in a ziplock bag for 3 minutes </li></ul><ul><li>Stone hardens in 20 minutes </li></ul><ul><li>In 24-48 hours it will have fully hardened </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  13. 20. Enhancement Methods <ul><li>Poor impressions may have to be enhanced by one of the following means: </li></ul><ul><ul><li>Forensic Photography – oblique, ultraviolet, infrared or other special methods </li></ul></ul><ul><ul><li>Physical Methods – latent powder, lifting impressions, or impressions on paper </li></ul></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  14. 21. Enhancement Methods <ul><li>Chemical Methods – reagents such as leuco crystal violet, amido 10 black, luminol or fuschin acid may be used </li></ul><ul><li>Digital Methods – Software such as Adobe Photoshop can be used to enhance impressions </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  15. 25. Known Shoes and Preparation of Exemplars <ul><li>Footwear from Suspected Persons: </li></ul><ul><ul><li>All footwear a suspect owns should be seized for comparison </li></ul></ul><ul><ul><li>Shoes are needed to make test impressions </li></ul></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  16. 27. Known Shoes and Preparation of Exemplars <ul><li>Elimination Footwear – Footwear worn by police officers, medical personnel should be accounted for when considering impressions left at scene </li></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  17. 28. Known Shoes and Preparation of Exemplars <ul><li>Known Test Impressions of Footwear </li></ul><ul><ul><li>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 </li></ul></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition
  18. 30. The Examination Process and Conclusions <ul><li>Areas of footwear which are examined by analyst include: </li></ul><ul><ul><li>Design of shoe </li></ul></ul><ul><ul><li>Physical Size and Shape </li></ul></ul><ul><ul><li>Wear marks </li></ul></ul><ul><ul><li>Individual Identifying Characteristics- cuts tar, gum etc </li></ul></ul>Chapter 19 CRC Press: Forensic Science, James and Nordby, 3rd Edition

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