Transcript Types of Evidence

Types of Evidence
Coach Whitaker
Vocabulary
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Evidence—something that tends to
establish or disprove a fact
Testimonial evidence—what is said in court
by a competent witness
Physical evidence—tangible items that
tend to prove some material fact
Indirect evidence—evidence providing only
a basis for inference about the disputed
fact
Vocabulary
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Circumstantial evidence—evidence based on
suggestion rather than personal knowledge or
observation
Individual evidence—material that can be related
to a single source
Class evidence—material that can be associated
only with a group of items that share properties
or characteristics
Probative value—the ability of evidence to prove
something that is material to a crime
Vocabulary
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Unknown sample—material that has been
collected from a known location but is of
unknown origin
Known sample—material that comes from
a proven or known source
Evidence
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2.
Evidence is something
that tends to establish
or disprove a fact
Evidence can be divided
into two general types:
Testimonial evidence—
statement made under
oath
Physical evidence—can
be any object or
material relevant in a
crime
Testimonial Evidence
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Eyewitness account
provides important
evidence leading to the
conviction of a criminal
(direct evidence)
Jurors are heavily
influenced by testimony
How accurate are
eyewitnesses? What
might influence their
accuracy?
Testimonial Evidence
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Common eyewitness errors
could include:
Crime scene was too dark
The encounter was too brief
Presence of a weapon
diverted attention
Stress and fear of the
incident
The time between the crime
and questioning
New information can
influence memory
Testimonial Evidence
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Police need to be careful in judging how
reliable an eyewitness might be—some
important points
The type of crime and how the witness saw it
Some types of witnesses are better at
remembering than others
Interviewing techniques or how info is
retrieved
How the witness knew the accused
How much time has passed
Memory Challenge
Directions:
You will have 30 seconds to view the next screen.
Try to memorize all 20 items you see!
You are NOT allowed to write anything down
You CANNOT talk to anyone else.
Items to remember ...
Neuroscience for Kids - http://faculty.washington.edu/chudler/puzmatch1.html
What do you remember?
You have 2 minutes to list as many of the items as you can!
How did you do?
All 20 – Awesome
15-19 – Great
10-14 – Pretty swell
5-9 – Could be better
4 or Less – Wake up
Crime Scene Challenge
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Now that your eyes and brain are warmed up, let’s
test your observation skills a bit more.
You will have 2 minutes to study the photograph of a
crime scene on the next slide.
Try to pay attention to details as you will be asked 10
questions about the crime scene!
You are not allowed to write anything down until
after the time is up.
Ready?
Answer each question below.
1. What color coffee mug was in the picture?
2. When was the deadline?
Yesterday
Blue
Red
Today
3. What time was on the clock on the wall?
Yellow
Tomorrow
10:40
11:05
4. How many sticky notes were on the whiteboard?
Four
Six
5. Which of the following was NOT in the picture? Stapler
6. What was the name on the plaque on the desk?
7. What color was the victim's shirt?
Black
8. How many plants were in the picture?
None
Bill
Blue
10. Where was the book in the picture? On a box
Eight
Trash Can
Brian
Printer
Carl
Red
One
9. What was the color of the marker in the desk drawer?
1:55
Two
Red
In the trash can
Blue
Green
Under the body
Activity
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Eye witness internet activity
FACES SKETCH
Physical Evidence
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A forensic scientist is
most interested in
physical evidence (called
real evidence)
Physical evidence can be
any object or material—
building, odor, hair, DNA
etc..
The variety of physical
evidence is unlimited and
is more reliable than
testimonial evidence
Physical Evidence
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Common types of PE:
Drugs, toxic substances, paints, gunshot
residue, firearms, impressions, petroleum,
alcohols, explosive residue, serial
numbers, documents, fibers, soil, glass,
blood, body fluid, fingerprints, hair, tissues
pollen, wood, bones, and tool marks
Physical Evidence
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Most evidence does not
prove a fact and is called
indirect evidence
Circumstantial evidence—
implies a fact or event
without actually proving it
The more CE there is, the
greater weight it carries
and is based on
probability and statistics
What is the Value of Physical
Evidence?
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PE can prove that crime has been committed
and set the scene for the investigation
PE can back up witness testimony or prove it
false
PE can link a suspect with a victim or with a
crime scene
PE can determine the ID of people associated
with a crime
Pecan allow investigators to reconstruct a crime
scene
Forensic Scientist’s Role
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The FS must determine if
there is a link with the
evidence and crime and if
physical evidence
collected is relevant to
the crime
An unknown sample is
compared to a know
sample
The FS may be apart of a
team that reconstructs
the crime scene
Individual versus Class Evidence
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The best evidence is anything that can be linked
to a unique, single source this is called individual
evidence
Examples—DNA, handwriting, fingerprints
Class evidence is an object that has
characteristics that is common with a group of
objects
Examples—blue jeans, t-shirts,
An object may have something that
individualizes it
Individual versus Class Evidence
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Probative value is the
ability of evidence to
prove something that is
material to a crime
(means supplying proof
or evidence)
Example—soil and red
paint on the jeans
together would increase
the probability that it was
apart of the crime
Probability Activity
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Probability and Class Evidence Activity
(28-31)
Trace Evidence
Trace evidence refers to physical evidence that
is found in small but measurable amounts, such
as strands of hair, fibers, or skin cells.
Locard’s Exchange Principle
"Every Contact Leaves a Trace"
The value of trace (or contact) forensic evidence was
first recognized by Edmund Locard in 1910. He was
the director of the very first crime laboratory in
existence, located in Lyon, France.
The Locard’s Exchange Principle states that "with contact between two
items, there will be an exchange." For example, burglars will leave traces
of their presence behind and will also take traces with them. They may
leave hairs from their body or fibers from their clothing behind and they
may take carpet fibers away with them.
Source: http://www.virtualsciencefair.org/2004/fren4j0/public_html/trace_evidence.htm
Examples of Trace Evidence
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Paint, Glass, Explosives, Ballistics, Fracture
Matching, Impressions, Body Fluids, DNA,
fingerprints, hair, and fibers
Investigator Tool Kit For Collecting
Evidence
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Angle mirror
Bloodborne pathogen kit
Body fluid collection kit
Camera and film
Chalk
Compass
Containers and envelopes
Scissors
Screwdrivers
Sexual assault kit
Sketching supplies
Wrecking bar
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Crayon and markers
Fingerprint kit
Flashlights
Knife
Magnifier
Measuring tape
Picks
Plaster
Pliers
Rope or tape
Spatula
tweezers
Common Physical Evidence
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Shoe and tire impressions, tools and tool
marks, broken glass, soils and minerals,
cigarette butts, rope and tape, alcohol and
drugs, weapons and ammo, clothing, hair
and fibers, body fluids, fingerprints
Tool Kit
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Make a collage of common tools with a
picture of each and tell me what you think
they are used for