"Incriminating Marks: Imprints vs Impressions"
In this first part of the series, we examine the differences between imprints and impressions as they relate to forensic evidence. While both types of marks can be left at
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About "Incriminating Marks: Imprints vs Impressions"
PowerPoint presentation about '"Incriminating Marks: Imprints vs Impressions"'. This presentation describes the topic on In this first part of the series, we examine the differences between imprints and impressions as they relate to forensic evidence. While both types of marks can be left at. The key topics included in this slideshow are . Download this presentation absolutely free.
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Slide1Incriminating MarksPart 1
Slide2What are we looking at? Imprints vs. Impressions Imprints vs. Impressions Very real differences Very real differences Determining the difference can determine how the evidence is collected Determining the difference can determine how the evidence is collected
Slide3Imprints Is a two-dimensional pattern on a hard surface Is a two-dimensional pattern on a hard surface Examples: Examples:
Slide4Impressions Is a three-dimensional indentation or pattern Is a three-dimensional indentation or pattern Formed when an object presses into a softer surface. Formed when an object presses into a softer surface. Examples: Examples:
Slide5Information Specific toShoeprints Can be impressed or “ visible ” Can be impressed or “ visible ” Many Different Ways to collect this evidence Many Different Ways to collect this evidence Many Different Factors involved in the analysis of this evidence Many Different Factors involved in the analysis of this evidence
Slide6Types of Shoeprints Visible (Imprint) Visible (Imprint) Stepped into something, then onto something Stepped into something, then onto something Impressed (Impression) Impressed (Impression) Stepped into something Stepped into something
Slide7How to collect ImprintEvidence Many different ways to collect, based on the type of shoeprint it is Many different ways to collect, based on the type of shoeprint it is Electrostatic Lifting Electrostatic Lifting Gelatin and Adhesive tape lifting Gelatin and Adhesive tape lifting Photography Photography Powdering and Imprints Powdering and Imprints Chemical Enhancements Chemical Enhancements
Slide8Electrostatic Lifting Used for lifting “ Visible ” Shoeprints Used for lifting “ Visible ” Shoeprints Uses Electricity to place a charge on the particles Uses Electricity to place a charge on the particles Used on many different surfaces: almost everything Used on many different surfaces: almost everything Video of Lifting Video of Lifting
Slide9Chemical Enhancement Tests on the residues found within the imprints Tests on the residues found within the imprints Examples of what can be found is: Examples of what can be found is:
Slide10How to collect ImpressionEvidence Photograph Photograph Casting Casting Is done differently depending on the location of the impression Is done differently depending on the location of the impression How to make a cast How to make a cast
Slide11 Comparing Evidence Most important FIND THE ORIGINAL OBJECT Most important FIND THE ORIGINAL OBJECT This is the “ known standard ” This is the “ known standard ” Database of shoe and Tire treads – used to exist! Law enforcement only has it now. Database of shoe and Tire treads – used to exist! Law enforcement only has it now.
Slide12Analysis of Evidence 3 Major steps to examining evidence 3 Major steps to examining evidence Determine what made the prints (class) Determine what made the prints (class) Determine the (individual) characteristics of the print Determine the (individual) characteristics of the print Comparing to Known Standards Comparing to Known Standards