Types of Evidence

This training module introduces and describes the following key concepts:

• Types of physical evidence frequently encountered at a property crime scene.
• Locard's Exchange Principle.
• Importance of maintaining the integrity of physical evidence.
• Sources of degradation of biological and trace evidence.

Physical evidence consists of tangible objects, such as biological material, fibers and latent fingerprints. Physical evidence is any object that can connect a victim or suspect to a crime scene. Biological evidence, which contains DNA, is not always visible to the naked eye.

Evidence may aid an investigator in re-creating the crime scene and establishing the sequence of events. Physical evidence can corroborate statements from the victim, witness and suspect. Physical evidence is objective and, when documented, collected and preserved properly, may be the only way to reliably place or link someone to a crime scene. Physical evidence is often referred to as the "silent witness."

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