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

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

3. 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.

4. 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

5. 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

6. 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+

7. 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

8. Spiral Search Method

9. Grid Method

10. Strip or Line Search

11. Quadrant or Zone Search

12. Final
Sketch
Rough
Sketch

14. Bird's eye view
3 – dimensional
representation

15. Computer
representation