1. Evidence

2. What is evidence?
• In the law evidence can be broken down into two
categories…
– Direct evidence
– Physical evidence

3. Direct evidence
• Direct evidence is
made in the form of a
statement made
under oath, such as a
witness pointing out a
person that they
believe committed a
crime
• We also call this
testimonial evidence

4. Physical evidence
• Physical evidence is
any object or material
that is relevant to a
crime including small
and large tangible
objects, and/or smells
and odors.
• This evidence is
collected by the CSI
then processed by a
lab technician

5. Why is it important?
• Physical evidence can…
– Prove a crime has been committed
– Corroborate testimony
– Link a suspect with a victim or crime scene
– Establish the identity of associated persons
– Allow reconstruction of events at a crime

6. • Evidence can also be broken down more by how
much “weight” it carries in court proceedings.

7. Indirect evidence
• Indirect evidence is evidence that does not
prove a fact; it only establishes a
hypothesis based on facts…most
evidence falls into this category

8. Circumstantial evidence
• Circumstantial evidence implies a fact or
event…such as possession of narcotics
• The greater the volume/amount of
circumstantial evidence there is the more
likely it is that it is factual (probability and
statistics.

9. What is good evidence?
• The rules of evidence define what evidence is
admissible and what evidence is not

10. • Material evidence is all evidence that is
relevant to a particular crime
• Evidence that proves something in a case
is what we call probative.
• You want to convict someone then you
better have material evidence that is
probative

11. Inadmissible evidence
• Hearsay is a form of evidence that is not
permissible in court because the person was not
under oath when the statement was made

12. Credibility
• The expert witness is the person that is
the expert in the field of science…they are
the presenter of information in court
• Credibility is established through
credentials, background, and experience
in the topic.

13. What makes it admissible?
• There are two court
rulings that have
largely governed the
admissibility of
evidence in court
– Frye vs. the United
States
– Daubert vs. Merrell
Dow Pharmaceutical,
Inc.

14. The Frye Standard
• The Frye standard states that in order to
be probative
– Testimony must be given by an expert witness
– The techniques used must have gained
general acceptance within its own field

15. The Daubert Ruling
• The Daubert ruling stated that the Frye
standard was not an absolute prerequisite
for admissibility in court, and that it was
the judge that was responsible for
determining validity
• The Frye standard was to be used only as
a guideline

16. Why did it change?
• The Daubert ruling changed the previous Frye
standard to help keep up with technological
advances in the field.
• The guideline is:
– The technique or theory must be testable
– The theory must be subject to peer review
– Potential error, and rate of error must be stated
– The techniques must follow a standard
– Consideration of the widespread acceptance, or lack
of, within the scientific community must be taken