Evidence Evidence can be divided into two broad types: Testimonial Evidence Physical/Biological Evidence

Testimonial Evidence Evidence given in the form of statements made under oath, usually in response to questioning

Physical/Biological Evidence Evidence having size, shape, or dimension. Physical evidence can take any form. The variety of physical evidence that may be encountered at a crime scene is infinite.

Examples of Physical/Biological Evidence Non-living Gun, bullets, tool marks, fibers, paint, etc. Biological Organic Usually associated with something living Saliva, urine, semen, hair, wood, pollen

What is the value of Physical/Biological Evidence? Can prove that a crime has been committed and set the scene for the investigation Can back up witness testimony or prove false Can link a suspect with a victim or with crime scene Can determine the identity of people associated with a crime Can allow investigators to reconstruct a crime

Two Types of Physical/Biological Evidence Individual Evidence Can be linked to a single source Ex: Fingerprints, handwriting, DNA patterns Class Evidence Most evidence is class evidence Characteristics are common to a group of similar objects Ex: Clothes, bullets, blood type AB+

Searching the Crime Scene There are 4 ways to search a crime scene for evidence. Spiral search method Grid method Strip or line search Quadrant or zone search

Spiral Search Method

Grid Method

Strip or Line Search

Quadrant or Zone Search

Final Sketch Rough Sketch

Bird's eye view 3 – dimensional representation

Computer representation