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Types of Evidence Types of Evidence 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 scientist’s 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. 2 Types of Evidence 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? 3 Types of Evidence 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? 4 Types of Evidence 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. 5 Types of Evidence What kind of evidence is a fingerprint? Physical 6 Types of Evidence What kind of evidence is a bitemark? Physical 7 Types of Evidence What kind of evidence is DNA? Physical 8 Types of Evidence What kind of evidence is this? Testimonial Video 9 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 person’s ability to remember details. 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. Types of Evidence Items to remember ... Neuroscience for Kids - http://faculty.washington.edu/chudler/puzmatch1.html 12 Types of Evidence 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 13 Types of Evidence Selective Attention 14 Types of Evidence Consider the Following Observe the following image. 15 Types of Evidence 16 Types of Evidence 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? 17 Types of Evidence Reliability of Eyewitness False 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-psychology-experiments.html video 18 The Bunny Effect The Bunny Effect CBS News Video Types of Evidence 20 Types of Evidence False Memories (balloon ride) video 21 Types of Evidence Video Test 22 Types of Evidence Jennifer Thompson’s The Innocence Project-CBS 60 Minutes 60 Minutes Part 2 23 Types of Evidence 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: Witness’s prior relationship with the accused Length of time between the offense and the identification Any prior identification or failure to identify the defendant Innocence Project > 5:23 Any prior identification of a person other than the defendant by the eyewitness 24 Did you know? Types of Evidence 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 person’s memory and their ability to identify a suspect? Let’s do a little research! 25 Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts Witness Factors Types of Evidence 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. 26 Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts Types of Evidence 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. 27 Types of Evidence The use of drugs can alter a person’s ability to recall the events of a crime even after they are no longer under the influence. 28 Types of Evidence A person’s 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. 29 Types ofScene Evidence & Suspect Factors Crime 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 perpetrator’s face. 30 Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts Types of Evidence 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. 31 Types of Evidence 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. 32 Types of Evidence The time of day in which the crime occurred as well as a person’s 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. 33 Crime Scene Challenge Types of Evidence 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? 34 Types of Evidence 35 Answer each question below. Types of Evidence 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? 10:40 11:05 1:55 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 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 Source: http://forensics.rice.edu/html/picture_begin.html Carl Red One 9. What was the color of the marker in the desk drawer? 10. Where was the book in the picture? On a box Brian Printer Two Red Blue Green In the trash can Under the body 36 Facial Composites Types of Evidence Investigators work with sketch artists and eyewitnesses to create facial composites, or sketches of a person’s 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. FACES – A software program that offers many options to help you recreate a person’s facial features. 37 Types of Evidence 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. DEMO FACES—a composite program by InterQuest 38 You will need a calculator in a day or two! Make sure you have one. (Was on your supply list) Types of Evidence 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. 40 Types of Evidence Forensic scientists consider the chemical and physical properties of materials they are investigating. 41 Types of Evidence Physical Properties Definition: anything you can observe or measure without changing the chemical identity of the substance Length Shape Color Temperature Density Hardness Solubility [what it dissolves in] Refractive index [how substance bends light] 42 Types of Evidence Physical Changes Changes in physical properties Chemical composition doesn’t change Tearing a piece of paper Dissolving salt in water Denting your car Spilling milk 43 Types of Evidence Can be observed when the substance changes its chemical composition Chemical Properties Reactivity with : Air (Flammability or oxidizing ability) Water Acid Base Sample may be destroyed during testing VIDEO 44 Types of Evidence 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 45 Types of Evidence LET’S PRACTICE! 1. Make a T chart (with two headers) on your paper. Physical Changes|Chemical 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. 46 Types of Evidence Work time! 1. Physical vs. Chemical Changes WS 2. Read/highlight back of WS, “Differentiating class and individual evidence” 3. Write a definition for class evidence and for individual evidence in your notebook as summary. 4. Work on witness experiment (plan, create surveys, find video clips or pics, talk to teachers, etc.) 47 Types of Evidence PHYSICAL EVIDENCE 48 Types of Evidence 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 49 Types of Evidence 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 50 Types of Evidence 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. 51 Types of Evidence 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 52 Types of Evidence 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? 53 Types of Evidence 54 Types of Evidence 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. (circumstantial—lots of people have blond hair) Size 11 sneaker print found near by (circumstantial—lots of people have big feet) Two observations together limit pool of suspects! 55 Types of Evidence Probability and Class Evidence Activity Get out your calculator! 56 Types of Evidence Can I tell a Blonde joke? 57 Types of Evidence 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, that’s not what I meant, but she’s 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 don’t 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 I’m already working on a murder case!” 58 Types of Evidence Other Evidence Pattern evidence—mostly in the form of imprints, indentations, striations, markings, fractures, or deposits Blood spatter Glass fracture Fire burn pattern Furniture position Projectile trajectory Tire marks or skid marks Clothing or article distribution Gunpowder residue Material damage Body position Toolmarks Modus operandi 59 Types of Evidence Significance of Physical Evidence Individual—can be identified with a particular person or a single source Blood DNA Typing Fingerprints Class—common to a group of objects or persons 60 Types of Evidence 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. 61 Types of Evidence Class vs. Individual Evidence, continued Which examples do you think could be individual evidence? 62 Types of Evidence Forensic Investigations Include some or all of these seven major activities: 1. Recognition—the ability to distinguish important evidence from unrelated material Pattern recognition Physical property observation Information analysis Field testing 2. Preservation through the collection and proper packaging of evidence 63 Types of Evidence Forensic Investigations, continued 3. Identification using scientific testing Physical properties Chemical properties Morphological (structural) properties Biological properties Immunological properties 4. 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 64 Types of Evidence Forensic Investigations, continued 5. Individualization in demonstrating that the sample is unique, even among members of the same class 6. Interpretation—giving meaning to all the information 7. 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 65 Types of Evidence 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 66