1. Testimonial evidence; a statement made under oath by a witness. Also called direct evidence or prima facie evidence. 2. Physical evidence; any object.

Types of Evidence

1. Testimonial evidence; a statement made under oath by a witness. Also called direct evidence or prima facie evidence.

2. Physical evidence; any object or material relevant in a crime. Also called real evidence

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.

Memory Challenge

Neuroscience for Kids - http://faculty.washington.edu/chudler/puzmatch1.html

Items to remember ...

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

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.

What is testimonial evidence?

The Bunny EffectCBS News Video

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).

Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts

Did you know?

What factors affect a person’s memory and their ability to identify a suspect?

Testimonial evidence can often be faulty. Things that can influence an eyewitness account:

•Darkness•Brief encounter•Stress and fear•Time between the crime and questioning•New information, other witnesses accounts•Leading questions•TV and newspaper reports

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.

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.

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.

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.

Witness Factors

Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts

A crime that is extremely traumatic for an eyewitness may affect his/her recall of the event. For example, a witness confronted with a weapon tends to focus on the weapon rather than the perpetrator’s face.

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.

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.

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.

Crime Scene & Suspect Factors

Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts

Stress and Memory

Importance of Forensic Evidence:

Crime Scene 1

Crime Scene 2

Case Example

60 Minutes: Eyewitness

The Innocence Project

A witness who is physically similar to the offender is more likely to give an accurate description.

Crime Scene Challenge

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? 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 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_begin.html

Facial Composites

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.

Indirect evidence; provides only a basis for inference about the disputed fact.

Circumstantial evidence; implies a fact or event without proving it. The more circumstantial evidence there is, the greater weight it carries.

Police or crime scene investigators collect physical evidence at a crime scene.

Forensic scientists in the lab then determine if there are links among the victim, crime scene, and suspect.

CRIME SCENE

VICTIMPERPETRATOR

1. IDENTIFICATION Determine the PHYSICAL or CHEMICAL

IDENTITY of a substance

2. COMPARISON

COMPARES A KNOWN SAMPLE WITH THAT OF A QUESTIONED SAMPLE to see if they have a COMMON ORIGIN (if you can link one to the other on the triangle).

In the Forensics Lab

Known sampleQuestioned samplefrom crime scene

Good scientific technique demands that control samples be run as well to validate the test methods and procedures.

How valuable is your evidence?

(1) INDIVIDUAL evidence that can be related to a single source with an extremely high degree of probability.

Fingerprints, DNA, handwriting, physical match (jigsaw fit)

(2) CLASS evidence is associated only with a group of items that share similar traits and not necessarily with a single source.

Glass, hair, fibers

1. The perpetrator was observed to be wearing a light blue T-shirt. This piece of shirt was found in the back seat of a suspects car.

Is this piece of blue T-shirt class or individual evidence?

This piece of light blue T-shirt was found at the scene of the crime.

Are the two pieces of shirt class or individual evidence?

2. Are the glass fragments class or individual evidence that can be uniquely associated with the broken bottle?

3. The broken bottom half of a bottle was found at the scene of a crime. The top was found with the suspect.

Can the top be uniquely associated with the bottom?

Explain.

4. This note was found at the bank.

This pad of paper was found in the desk of a suspect. Can the note be individualized to the pad?

5. An empty beer can was found at the scene of a crime.

A case of the same kind of beer

..along with three beer tabs

were found in the suspect’s garage.

Is the evidence class or individual??

Explain.

6. This shoe print was found at the scene of a hit-and-run automobile accident. Witnesses obtained a description of the car. Explain how a suspects shoe can be individualized to match a print.

7. Section A of The Bucks County Courier Times for Tuesday, August 20, 2012 was found at the scene of a crime.

Section B of the same newspaper was found in the home of a suspect. Is Section B individual or class evidence?

8. Powder #1 was found in a baggy in a suspects pocket.

Powder #2 was found on the victim.

IS POWDER #1 CLASS OR INDIVIDUAL EVIDENCE?

CAN IT BE INDIVIDUALIZED TO POWDER #2?

9. Are these cut papers class or individual evidence? Explain.

10. Are these torn papers class or individual evidence? Explain.

Posted: Thursday, 21 February 2008 5:13PM

SAN FRANCISCO (KCBS)  -- A San Francisco jury Thursday convicted 74-year-old John Puckett for the 1972 rape and murder of Diana Sylvester. The Boston native had just gotten her first job at U.C.S.F. Medical Center when she was killed in her Inner Sunset District apartment.

VALUE of the evidence

WHAT ARE THE STATISTICS AND PROBABILITY ASSOCIATED WITH THE EVIDENCE?

Puckett insisted he was innocent, saying that although DNA at the crime scene happened to match his, it belonged to someone else.

At Puckett's trial earlier this year, the prosecutor told the jury that the chance of such a coincidence was 1 in 1.1 million.

The PRODUCT RULE

¼ of the population has brown hair

½ of the population is male

½ of the population wears jeans

1/3 of the population wears sneakers

What is the probability that one person is male, has brown hair, is wearing jeans and sneakers?? ¼ of the population has brown hair

½ of the population is male

½ of the population wears jeans

1/3 of the population wears sneakers

THE PROBABILITY RULE:

¼ x ½ x ½ x 1/3 = 1/48 = .0208

Or .0208 x 100 = 2.08 %

How many students at CR South would be likely to be male, have brown hair, and be wearing jeans and sneakers??

.0208 x 2100 (current pop) =

43.75 students

Even Physical Evidence can be wrong…

Extreme care must be taken when collecting and handling evidence, evaluating evidence, and presenting evidence. The high standards of the scientific method try to eliminate all subjectivity, but as we have just seen…some of the topics that we will learn about call for some degree of subjectivity.

That is why “expert witnesses” will disagree and also why many of you may disagree in some of our labs. It is important to realize that Forensic Science does not have all the answers and sometimes you may not be able to build a case using physical evidence alone. Recognize and understand the limitations of some of these techniques.