Incriminating Marks Part 1

What are we looking at? Imprints vs. Impressions Imprints vs. Impressions  Very real differences  Determining the difference can determine how the evidence is collected

Imprints Is a two-dimensional pattern on a hard surface Is a two-dimensional pattern on a hard surface  Examples:

Impressions 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:

Information Specific to Shoeprints 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

Types of Shoeprints Visible (Imprint) Visible (Imprint)  Stepped into something, then onto something Impressed (Impression) Impressed (Impression)  Stepped into something

How to collect Imprint Evidence 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  Gelatin and Adhesive tape lifting  Photography  Powdering and Imprints  Chemical Enhancements

Electrostatic 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

Chemical Enhancement Tests on the residues found within the imprints Tests on the residues found within the imprints  Examples of what can be found is:

How to collect Impression Evidence Photograph Photograph Casting Casting  Is done differently depending on the location of the impression How to make a cast How to make a cast

Comparing Evidence Most important  FIND THE ORIGINAL OBJECT Most important  FIND THE ORIGINAL OBJECT  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. Database of shoe and Tire treads Database of shoe and Tire treads

Analysis of Evidence 3 Major steps to examining evidence 3 Major steps to examining evidence  Determine what made the prints (class)  Determine the (individual) characteristics of the print  Comparing to Known Standards