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Chapter 18

Chapter 18. Forensic Footwear Evidence. What information can you gather from this foot? . What is Forensic Footwear Evidence?.

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Chapter 18

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  1. Chapter 18 Forensic Footwear Evidence

  2. What information can you gather from this foot?

  3. What is 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

  4. Forms of Footwear Impressions =Those that remain after a shoe has permanently deformed a surface. =Those patent or latent prints left on a non-giving surface.

  5. Forms of Footwear Impressions • Note: Very often the less visible impressions actually retain greater detail than those that result from heavier deposits of residue, dust, or blood. Three Dimensional Impressions Two Dimensional Impressions

  6. Information from Footwear Impressions --Proving a suspect’s presence at a crime and thus possible participation in the crime --Aided by use of FBI footwear database that includes thousands of shoe designs --Based o CLASS characteristics . . .. changes in or absence of random individual characteristics are normally not used to eliminate a shoe --Can help lead to uncovering other impressions or physical evidence

  7. Information from Footwear Impressions --Recording dimen-sions of impressions can allow for general estimate of shoe size --Refers to how someone walks --Measurements from impressions include stride, step width, and walking pace --Note: not reliably used as a means of personal ID -- More than one print design found can suggest the # of people who potentially committed the crime --Databases can store footwear impressions recovered from scenes and can be used to find a matches or links between different crimes (helpful with repetitive crimes like burglaries) --Observing impression series that can result in following the path of an individual (ex illegal aliens and kidnapped children)

  8. Number of perpetrators? • Identification of Footwear ? • Association with Other Evidence • Determination of Shoe Size • Tracking

  9. Video Duration~1:28

  10. Location and Recovery of Footwear Impressions http://www.knoxandassociates.com/photo.php

  11. Recovery (cont.)

  12. Recovery (cont.) 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 Electrostatic Lifting FilmThis foil backed black mylar produces exceptional detail in even the most subtle dust impressions

  13. Electrostatic Lifting Device Text and image from: Introduction to Criminalistics: The Foundation of Forensic Science  By Barry A. J. Fisher, William J. Tilstone, Catherine Woytowicz

  14. Recovery (cont.) Three – Dimensional Impressions • Dental stone is primary means 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 Pre-Measured Dental Stone

  15. Enhancement Methods • Poor impressions may have to be enhanced by one of the following means: • NOTE: Enhancement similar to fingerprints

  16. Recovered print Analysis: • Need to have known shoes and exemplars to compare against Footwear from Suspected Persons: • All footwear a suspect owns should be seized for comparison • Shoes are needed to make test impressions

  17. 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 • Elimination Footwear – Footwear worn by police officers, medical personnel should be accounted for when considering impressions left at scene

  18. The Examination Process and Conclusions • Areas of footwear which are examined by analyst include:

  19. Quia Quiz • http://www.quia.com/quiz/1371545.html

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