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Chapter 22 – Impression Evidence. FRSC 7104 Criminalistics I Professor Bensley. FRSC 7104 – Chapter 22Objectives. After studying this chapter, the student should be able to: Describe the process of serial numbers restorations
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Chapter 22 – Impression Evidence FRSC 7104 Criminalistics I Professor Bensley
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
FRSC 7104 – Chapter 22 Outline • Serial Number Restoration
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
FRSC 7104 – Chapter 22 Outline • Introduction to Impression Evidence • Indented impressions
FRSC 7104 – Chapter 22 Outline • Residue transfer prints (imprints)
FRSC 7104 – Chapter 22 Outline • Examination of Footwear Impressions • Introduction • Two-Dimensional • Adhesive Lift • Gelatin Lift
2-D Footprint Lifting Methods Left – Hinged Footprint Residue Lifter Below – Rubber/ Gelatin Hinged Footprint Lifter
FRSC 7104 – Chapter 22 Outline • Electrostatic Dust Lifter
FRSC 7104 – Chapter 22 Outline • Three-dimensional (Cast) • Plaster of Paris • Dental Stone
FRSC 7104 – Chapter 22 Outline • Snow prints 1. 2. 4. 3.
FRSC 7104 – Chapter 22 Outline • Collecting Known Standards
FRSC 7104 – Chapter 22 Outline • Footwear Impression Comparisons
FRSC 7104 – Chapter 22 Outline • Bloody Footprints • Coomassie Brilliant Blue • Leucocrystal Violet
FRSC 7104 – Chapter 22 Outline • Footwear Impression Databases
FRSC 7104 – Chapter 22 Outline • Tire Tread Impressions • Introduction
FRSC 7104 – Chapter 22 Outline • Tire Impressions vs. Tire Tracks • Impressions • Tire Tracks
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
FRSC 7104 – Chapter 22 Outline • Evidence Collection and Comparisons • Databases
FRSC 7104 – Chapter 22 Outline • Tire Design
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