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Chapter 22 – Impression Evidence

Chapter 22 – Impression Evidence

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Chapter 22 – Impression Evidence

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  1. Chapter 22 – Impression Evidence FRSC 7104 Criminalistics I Professor Bensley

  2. FRSC 7104 – Chapter 22Objectives After studying this chapter, the student should be able to: Describe the process of serial numbers restorations Recognize the various types and significance of impression evidence  Understand the detection, collection and evaluation of footwear impressions Understand the detection, collection and evaluation of tire impressions

  3. FRSC 7104 – Chapter 22 Outline • Serial Number Restoration

  4. FRSC 7104 – Chapter 22 Outline • Procedure of Analysis for Obliterated Serial Numbers • Inspection • Polishing Procedure • Magnetic or Magnaflux® Procedure • Chemical Procedure • Electrochemical Procedure • Heat Procedure • Results of Serial Number Restoration Procedures

  5. FRSC 7104 – Chapter 22 Outline

  6. FRSC 7104 – Chapter 22 Outline • Introduction to Impression Evidence • Indented impressions

  7. FRSC 7104 – Chapter 22 Outline • Residue transfer prints (imprints)

  8. FRSC 7104 – Chapter 22 Outline • Examination of Footwear Impressions • Introduction • Two-Dimensional • Adhesive Lift • Gelatin Lift

  9. 2-D Footprint Lifting Methods Left – Hinged Footprint Residue Lifter Below – Rubber/ Gelatin Hinged Footprint Lifter

  10. FRSC 7104 – Chapter 22 Outline • Electrostatic Dust Lifter

  11. Electrostatic Dust Lifter

  12. Electrostatic Dust Lift Procedure

  13. FRSC 7104 – Chapter 22 Outline • Three-dimensional (Cast) • Plaster of Paris • Dental Stone

  14. FRSC 7104 – Chapter 22 Outline

  15. FRSC 7104 – Chapter 22 Outline • Snow prints 1. 2. 4. 3.

  16. FRSC 7104 – Chapter 22 Outline

  17. FRSC 7104 – Chapter 22 Outline • Collecting Known Standards

  18. FRSC 7104 – Chapter 22 Outline • Footwear Impression Comparisons

  19. FRSC 7104 – Chapter 22 Outline • Bloody Footprints • Coomassie Brilliant Blue • Leucocrystal Violet

  20. FRSC 7104 – Chapter 22 Outline • Footwear Impression Databases

  21. FRSC 7104 – Chapter 22 Outline • Tire Tread Impressions • Introduction

  22. FRSC 7104 – Chapter 22 Outline • Tire Impressions vs. Tire Tracks • Impressions • Tire Tracks

  23. Various Tire Tracks

  24. FRSC 7104 – Chapter 22 Outline • Residue (Imprints) vs. Indentations (Impressions) • Evidentiary Value of Tracks and Impressions • Divergent Surfaces • Skid Marks • Tire circumference • Tread Width • Turning Diameter

  25. FRSC 7104 – Chapter 22 Outline • Evidence Collection and Comparisons • Databases

  26. FRSC 7104 – Chapter 22 Outline • Tire Design

  27. FRSC 7104 – Chapter 22 Outline • Chapter Summary • Impressions can be two- or three-dimensional • Most common impression evidence types are footwear, tire treads and serial numbers • Impression evidence can be individualized if sufficient unique characteristics are present • Preserving impressions is very important and can be done with photography or casting • Serial numbers are another type of impression evidence that can be restored