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

can take any form

Infinite variety may be at a crime scene

Examples of

Physical/Biological Evidence

Physical

Non-living

Gun, bullets, tool marks, fibers, paint, etc.

Biological

Organic, usually associated with something

living

Saliva, urine, semen, hair, blood, 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

Characteristics are common to a group

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

Rough Sketch

Final Sketch

Bird's eye view

3 – dimensional

representation

Computer representation