Evidence Forensics 352 Locard Exchange Principle A cross

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Evidence Forensics 352

Evidence Forensics 352

Locard Exchange Principle • A cross transfer of evidence always occurs between suspect and

Locard Exchange Principle • A cross transfer of evidence always occurs between suspect and victim or locale • Example : Murder by Numbers

What are the two types of evidence? 1. Direct Evidence – establishes a fact

What are the two types of evidence? 1. Direct Evidence – establishes a fact and does not make any inferences Examples: – Confessions – Video cameras – Testimony of Witness *** Remember not very reliable but has big influence on the jury!!!

What are the two types of evidence? 2. Indirect Evidence; aka circumstantial – implies

What are the two types of evidence? 2. Indirect Evidence; aka circumstantial – implies a fact without actually proving it – there could be another explanation for evidence being present – most evidence is circumstantial

What is circumstantial evidence? • Classified as physical or trace evidence Seen by naked

What is circumstantial evidence? • Classified as physical or trace evidence Seen by naked eye Processing Sources Physical Trace YES NO Documented with photos Use chemical methods or an alternate light sources to identify blood shed, bullet casings hair, bodily fluids, powders

Class versus Individual • Class Evidence = object has characteristics common to a group

Class versus Individual • Class Evidence = object has characteristics common to a group of similar objects • Individual Evidence = object can be linked to a unique, single, specific source Let’s take a look at some examples:

Class or Individual Example • A pistol was found in a theatre where a

Class or Individual Example • A pistol was found in a theatre where a man was shot. A suspect known to have owned a Derringer like this one was apprehended. Would this gun be considered individual or class evidence?

Class or Individual? • Can it be determined whether theses bullets were fired from

Class or Individual? • Can it be determined whether theses bullets were fired from the same gun? How can bullets be individualized to a gun? Explain.