Types of Evidence

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Types of Evidence
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Objectives

• You will understand
• The value of indirect and direct evidence in a
  court of law.
• That eyewitness accounts have limitations.
• What physical evidence can and cannot prove in
  court.
• That the forensic scientists main goal is to
  find a unique source for the evidence.
• You will be able to
• Explain the difference between indirect and
  direct evidence.
• Describe what is meant by physical evidence and
  give examples.
• Distinguish individual evidence from class
  evidence.
• Determine the significance of class evidence.

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5 questions Lawyers should NEVER ask a witness in
court

• 1. Is it true that you were present until you
  left the building?
• 2. Who was it that got killed in the accident -
  you or your sister?
• 3. When the two cars collided, how far away from
  each other were they?
• 4. Was that the first time that your brother had
  committed suicide?
• 5. When he took your photo, were you present?

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Learning Targets

• Distinguish between testimonial and physical
  evidence.
• What factors influence the reliability of
  eyewitness testimony?
• What methods improve accuracy of an eyewitness
  identifying a suspect correctly?

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Classification of Evidence

• Testimonial evidence is a statement made under
  oath also known as direct evidence or prima
  facie evidence.
• "at first face" or "at first appearance"
• Physical evidence is any object or material that
  is relevant in a crime also known as indirect
  evidence. Examples are hair, fiber, fingerprints,
  documents, blood, soil, drugs, toolmarks,
  impressions, glass.

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What kind of evidence is a fingerprint?

• Physical

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What kind of evidence is a bitemark?

• Physical

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What kind of evidence is DNA?

• Physical

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What kind of evidence is this?

• Testimonial

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What is testimonial evidence?
Testimonial evidence includes oral or written
statements given to police as well as testimony
in court by people who witnessed an event.
Eyewitness accounts can be a useful tool in
helping investigators with analyzing a crime
scene, but are not viewed to be highly reliable.
In addition, eyewitness identifications (right or
wrong) can have a big influence on the outcome of
an investigation or trial. People are likely to
view the same scene in different ways depending
on their positions, line of sight, familiarity
with the area, and other factors that can
interfere with a persons ability to remember
details.
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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.
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Items to remember ...
Neuroscience for Kids - http//faculty.washington
.edu/chudler/puzmatch1.html
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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
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• Selective Attention

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Consider the Following

• Observe the following image.

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(No Transcript)
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• What color was the car to the left of the stop
  sign?
• What type of vehicle was sitting at the right of
  the stop sign?
• What color was the vehicle on the right?
• Which way was the stop sign facing?

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Reliability of EyewitnessFalse Memory
Experiments

• Renowned psychologist Elizabeth Loftus conducted
  false memory experiments. In this experiment,
  subjects were shown an image of a car near an
  intersection.
• The researchers asked the subjects who had seen
  the yield sign questions that deliberately
  included the words "stop sign." Researchers did
  the opposite with subjects who were shown the
  stop sign image.
• Results of this experiment showed that subjects
  created false memories as they recalled not the
  image they had seen but rather the information
  that had been implanted.
• http//www.ehow.com/info_7935459_forensic-psycholo
  gy-experiments.html

video
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The Bunny Effect
The Bunny EffectCBS News Video
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(No Transcript)
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• False Memories (balloon ride)

video
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• Video

• Test

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• Jennifer Thompsons
• The Innocence Project-CBS 60 Minutes
• 60 Minutes Part 2

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Reliability of Eyewitness

• Factors that affect accuracy
• Nature of the offense and the situation in which
  the crime is observed
• Characteristics of the witness
• Manner in which the information is retrieved
• Additional factors
• Witnesss prior relationship with the accused
• Length of time between the offense and the
  identification
• Any prior identification or failure to identify
  the defendant
• Any prior identification of a person other than
  the defendant by the eyewitness

Innocence Project gt 523
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Did you know?
According to The Innocence Project (2008)
"Eyewitness misidentification is the single
greatest cause of wrongful convictions
nationwide, playing a role in more than 75 of
convictions overturned through DNA testing."
Still, the criminal justice system profoundly
relies on eyewitness identification and testimony
for investigating and prosecuting crimes (Wells
Olson, 2003).
What factors affect a persons memory and their
ability to identify a suspect? Lets do a little
research!
Source http//www.helium.com/items/1276135-accura
te-eyewitness-accounts
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Witness Factors

• Age may play a role in the accuracy of an
  eyewitness statement or identification of a
  suspect. Studies have shown that when a lineup
  contains the actual culprit, both young children
  and elderly perform well, but when the lineup
  does not contain the culprit there is a higher
  rate of mistaken identifications.

Source http//www.helium.com/items/1276135-accura
te-eyewitness-accounts
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• The race of the witness may also play a role. The
  Cross Race Effect (CRE) is a phenomenon in which
  people are better at recognizing faces of their
  own race rather than those of other races.

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• The use of drugs can alter a persons ability to
  recall the events of a crime even after they are
  no longer under the influence.

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• A persons memory of an event can be influenced
  by other witnesses, investigators, and/or the
  media. Investigators use open-ended questioning
  and follow procedures for conducting line-ups to
  limit their influence on a witness memory of an
  event or identification of a suspect.

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Crime Scene Suspect Factors

• A crime that is extremely traumatic for an
  eyewitness may affect his/her recall of the
  event.
• Ex. a witness confronted with a weapon tends to
  focus on the weapon rather than the perpetrators
  face.

Source http//www.helium.com/items/1276135-accura
te-eyewitness-accounts
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• Someone who is able to focus on a perpetrator's
  face for a minute or longer will tend to have a
  more accurate memory than someone who saw the
  person for only a few seconds.

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• Studies have shown that faces that are either
  highly attractive, highly unattractive, or
  distinctive are more likely to be accurately
  recognized. Simple disguises, such as hats or
  sunglasses, can interfere with accurate
  eyewitness identification. However, body
  piercings and tattoos increases the likelihood of
  an accurate identification.

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• The time of day in which the crime occurred as
  well as a persons view of the scene may affect
  what a he/she is able to see.
• In addition, a person who is familiar with the
  area in which the crime took place, may have a
  better recall of the positions of the victims or
  suspects.

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Crime Scene Challenge

• Now that your eyes and brain are warmed up, lets
  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?

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(No Transcript)
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Answer each question below.
1. What color coffee mug was in the picture?
Blue Red Yellow 2. When was the
deadline? Yesterday Today
Tomorrow 3. What time was on the clock on the
wall? 1040 1105 155 4. How
many sticky notes were on the whiteboard? Four
Six Eight 5. Which of the following was NOT
in the picture? Stapler Trash Can
Printer   6. What was the name on the plaque on
the desk? Bill Brian Carl
  7. What color was the victim's shirt?
Black Blue Red   8. How many plants
were in the picture? None One
Two 9. What was the color of the marker in
the desk drawer? Red Blue
Green 10. Where was the book in the
picture? On a box In the trash can
Under the body
Source http//forensics.rice.edu/html/picture_beg
in.html
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Facial Composites
Investigators work with sketch artists and
eyewitnesses to create facial composites, or
sketches of a persons face. Today many police
departments are using facial reconstruction
software to help them with this task.
The composite may be used internally to assist
officers in identifying the suspect or used
externally through local media (radio, TV, and
newspaper) to solicit leads from citizens.
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Eyewitness

• New technology is helping eyewitnesses to be able
  to describe suspects.
• A police composite may be developed from the
  witness testimony by a computer program or
  forensic artist.

FACESa composite program by InterQuest
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You will need a calculator in a day or two! Make
sure you have one. (Was on your supply list)
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Physical Evidence

• As a result of the influences on eyewitness
  memory, physical evidence becomes critical.
• Identity and origin of physical evidence is main
  task of forensic scientist.

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• Forensic scientists consider the chemical and
  physical properties of materials they are
  investigating.

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Physical Properties

• Length
• Shape
• Color
• Temperature
• Density
• Hardness
• Solubility what it dissolves in
• Refractive index how substance bends light

• Definition anything you can observe or measure
  without changing the chemical identity of the
  substance

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Physical Changes

• Changes in physical properties
• Chemical composition doesnt change
• Tearing a piece of paper
• Dissolving salt in water
• Denting your car
• Spilling milk

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Chemical Properties

• Can be observed when the substance changes its
  chemical composition

• Reactivity with
• Air (Flammability or oxidizing ability)
• Water
• Acid
• Base
• Sample may be destroyed during testing

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Chemical Changes

• Changes in chemical composition
• NEW substance MUST be present

• Burning
• Rusting
• Formation of new gas
• Formation of new solid
• Change in pH
• Growing new cells
• Digestion

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LETS PRACTICE!

1. Make a T chart (with two headers) on your paper.
   Physical ChangesChemical Changes
2. Sort the cards into the two categories.
3. Let me check.
4. Copy the examples into your chart.
5. Practice with the worksheet.

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• Work time!
• Physical vs. Chemical Changes WS
• Read/highlight back of WS, Differentiating class
  and individual evidence
• Write a definition for class evidence and for
  individual evidence in your notebook as summary.
• Work on witness experiment (plan, create surveys,
  find video clips or pics, talk to teachers, etc.)

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Physical Evidence
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Warm up (Think, Pair, Share!)

• If a forensic investigator has just the right
  evidence, what are some specific facts the
  evidence could prove? (For example, it can prove
  that a crime was committed.)
• List the following types of evidence in your
  journal. What do you think each one means? Share
  with your partner.
• Transient evidence Conditional evidence
• Circumstantial evidence

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Physical Evidence

• Is generally more reliable than testimonial
  evidence
• Can prove that a crime has been committed
• Can corroborate or refute testimony
• Can link a suspect with a victim or with a crime
  scene
• Can establish the identity of persons associated
  with a crime
• Can allow reconstruction of events of a crime

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Reconstruction

• Physical evidence can be used to answer questions
  about
• What took place at a crime scene
• The number of people involved
• The sequence of events

A forensic scientist compares the questioned or
unknown sample from the crime scene with a sample
of known origin.
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Transient evidence is temporary easily changed
or lost usually observed by the first officer at
the scene.

• Odors such as perfume, putrification, gasoline,
  cigarette smoke
• Temperature of a coffee pot, car hood, dead body,
  or water in bathtub
• Imprints and indentations such as footprints in
  sand, fingerprints in dust, teeth marks in
  perishable foods

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• Conditional evidence is produced by a specific
  event or action important in crime scene
  reconstruction and in determining the set of
  circumstances or sequence within a particular
  event.
• Lights on or off?
• Garage door up or down?
• Door open or closed?
• Windows locked or unlocked?
• Position of body or furniture?

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(No Transcript)
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• Circumstantial evidence implies a fact or event
  without actually proving it.
• More circumstantial evidence more weight b/c of
  probability and statistics
• Ex A blond hair is found in the hand of a murder
  victim having black hair.
• (circumstantiallots of people have blond hair)
• Size 11 sneaker print found near by
• (circumstantiallots of people have big feet)
• Two observations together limit pool of suspects!

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• Probability and Class Evidence Activity
• Get out your calculator!

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• Can I tell a Blonde joke?

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• The local police force was looking for a new
  detective, so a Blonde went in to interview for
  the job. Okay, honey, the sheriff asked, What is
  1 and 1? Eleven, she replied. The sheriff
  thought to himself, thats not what I meant, but
  shes right. Then the sheriff asked, What two
  days of the week start with the letter T? Today
  and tomorrow she replied. He was again surprised
  that the Blonde supplied a correct answer that he
  had never thought of himself.  Now, listen
  carefully. Who killed Martin Luther King? Asked
  the sheriff. The Blonde thought really hard for a
  minute and finally admitted she had no idea. The
  sheriff replied, Well, why dont you go home and
  work on that one for a while? So, the Blonde
  left and went home. When she walked through the
  door her husband asked her how the interview
  went. She replied , It went great! First day on
  the job and Im already working on a murder
  case!

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Other Evidence

• Pattern evidencemostly in the form of imprints,
  indentations, striations, markings, fractures, or
  deposits

• Clothing or article distribution
• Gunpowder residue
• Material damage
• Body position
• Toolmarks
• Modus operandi

Blood spatter Glass fracture Fire burn
pattern Furniture position Projectile
trajectory Tire marks or skid marks
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Significance of Physical Evidence

• Individualcan be identified with a particular
  person or a single source

Blood DNA Typing
Fingerprints
Classcommon to a group of objects or persons
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Class vs. Individual Evidence
These fibers are class evidence there is no way
to determine if they came from this garment.

• The large piece of glass fits exactly to the
  bottle it is individual evidence.

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Class vs. Individual Evidence, continued
Which examples do you think could be individual
evidence?
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Forensic Investigations

• Include some or all of these seven major
  activities
• Recognitionthe ability to distinguish important
  evidence
• from unrelated material
• Pattern recognition
• Physical property observation
• Information analysis
• Field testing
• Preservation through the collection and proper
  packaging of evidence

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Forensic Investigations, continued

• Identification using scientific testing
• Physical properties
• Chemical properties
• Morphological (structural) properties
• Biological properties
• Immunological properties
• Comparison of class characteristics measured
  against those of known standards or controls if
  all measurements are equal, then the two samples
  may be considered to have come from the same
  source or origin

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Forensic Investigations, continued

• Individualization in demonstrating that the
  sample is unique, even among members of the same
  class
• Interpretationgiving meaning to all the
  information

• Reconstruction of the events in the case
• Inductive and deductive logic
• Statistical data
• Pattern analysis
• Results of laboratory analysis

Henry C. Lee and Jerry Labriola, Famous Crimes
Revisited, 2001
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FBI Investigation

• Read a case investigated by the FBI. Observe the
  various units of their lab and read the section
  How Did They Do That?
• www.fbi.gov/kids/6th12th/investigates/investigates
  .htm