1. Dr. Jason Mayberry Castle View High School
Types of Evidence
Dr. Jason Mayberry
Castle View High School

2. Use of Evidence
Evidence: anything that tends to establish or disprove the innocence or guilt of a individual.
When gathering and evaluating evidence it is important to be aware of the difference between observation and inference.
Observations = Facts about what is perceived through the five senses
Inferences = a logical interpretation based upon prion knowledge and experience.
Experience
Inference

3. Observations Any information collected with the senses.
Quantitative – measureable or countable
3 meters long
4 marbles
50 kilograms
35 degrees Celsius
Qualitative – describable, not measureable
red flowers
smells like fresh baked cookies
Tastes bitter
Heard a loud “pop”

4. Inference Conclusions based on observations.
The process of drawing a conclusion from given evidence.
Example:
Observations:
I hear people screaming
I smell cotton candy, popcorn, and hamburgers
I see a lot of people
Inference = ?

5. Look at these two sets of animal tracks.
List 3 OBSERVATIONS
Make an INFERENCE

6. Now what do you think?
Make 3 OBSERVATIONS
Make an INFERENCE

7. Now what do you think?
Make 3 OBSERVATIONS
Make an INFERENCE

8. Proper use of Inference
Are Inferences good or Bad?
Can mislead investigators due to individual bias.
Can be helpful in leading investigators.
Can be testable hypotheses about a crime.

9. Classification of Evidence
“The major role of the forensic scientist is to determine if there are links among 1) the evidence, 2) the victim, 3) the crime scene, and 4) the suspect.”
Evidence
Testimonial Individual statements about their observations (prima facie)
Physical
Any tangible object or material relevant to a crime (real evidence)
Transient
Pattern
Conditional
Transfer
Associative
Direct proves a fact or event without inference (if true testimonial is more likely to be Direct)
Indirect (Circumstantial)
Implies a fact or event with proving it
Testimonial and Physical can be: or
More and unique = Increasing probative value
Testimonial and Physical can be:
Class evidence with characteristics common to a group or
Individual
Evidence that points directly to a single individual or object
More and unique = Increasing probative value

10. Testimonial Evidence
Tell me again what you saw?

11. Eyewitness Exercise
Choose several people to be observers and choose two people to be investigators.
Allow the observers to look at the picture for 30 seconds. The investigators should not look at the picture.
After 30seconds,the investigators should begin questioning the observers. Each Investigator should question each observer. Then, the Investigators should attempt to reconstruct the scene based on the "eyewitness testimony".

13. Reliability of Eyewitness
Factors:
Nature of the offense and the situation in which the crime is observed
Characteristics of the witness
Manner in which the information is retrieved
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
Any prior identification of a person other than the defendant by the eyewitness

14. Flashbulb Memories
Many victims of crimes have something that is called a flashbulb memory
This is a vivid recollection of dramatic or emotionally charged events
Example: Can anyone tell me what you were doing when a tragic or momentous event occurred?

15. You Be the Eyewitness Imagine you are at a gas station buying milk
A man walks in, threatens the employee at the counter, robs the cash register, and runs out
The entire ordeal lasts about five seconds
This is the man you saw…

17. You Be the Eyewitness
The police have asked you to help them identify the perpetrator
They will show you a set of pictures, and it is your responsibility to select the picture of the man you saw rob the gas station…

19. How Did You Do? So, which picture did you choose?
And the correct answer was... #2
Were you right?
What does this tell you about eyewitness testimony?

20. The Facts
In this country, it is estimated that 75% of wrongly convicted defendants, later cleared by DNA evidence, were convicted based largely on eyewitness testimony.

21. According to Research…
Studies show that the longer it takes an eyewitness to decide if the perpetrator is in a lineup, the less confident they actually are about their decision
Why?
Eyewitnesses typically take several minutes to point out the perpetrator because they often feel pressured to choose the correct one
However, if they are truly confident, they should be able to decide in under 10 seconds

22. Choosing From a Lineup
Research from Buckhout (1974) and Wells (1993) indicate that an eyewitness is more likely to falsely identify a person in a set of lineup photographs if there is anything that separates one picture from another
For example:
If one picture is larger than the others
If facial features in all the photographs are not identical

23. Ronald Cotton Case Study
e=related

24. Physical Evidence

25. Value of Physical Evidence
Generally more reliable than testimonial
Can corroborate or refute testimony
Can prove that a crime has been committed
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

26. Types of Physical Evidence
Transient Evidence —temporary; easily changed or lost; usually observed by the first officer at the scene
Pattern Evidence —produced by direct contact between a person and an object or between two objects
Transfer Evidence — any substance such as blood, fluids, hairs, fibers, paint, and skin that is exchanged between an assailant and the victim.
Conditional Evidence —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
Associative Evidence —items that may associate a victim or suspect with a scene or each other; i.e., personal belongings

27. Examples of Transient Evidence
Odor—putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke
Temperature—surroundings, car hood, coffee, water in a bathtub, cadaver
Imprints and indentations—footprints, teeth marks in perishable foods, tire marks on certain surfaces
Markings

28. Examples of Pattern Evidence
Pattern Evidence—most are in the form of imprints, indentations, striations, markings, fractures or deposits.
Clothing or article distribution
Gun powder residue
Material damage
Body position
Tool marks
Modus operandi
Blood spatter
Glass fracture
Fire burn pattern
Furniture position
Projectile trajectory
Tire marks or skid marks

29. Examples of Conditional Evidence
Light—headlight, lighting conditions
Smoke—color, direction of travel, density, odor
Fire—color and direction of the flames, speed of spread, temperature and condition of fire
Location—of injuries or wounds, of bloodstains, of the victim’s vehicle, of weapons or cartridge cases, of broken glass
Vehicles—doors locked or unlocked, windows opened or closed, radio off or on (station), odometer mileage
Body—position, types of wounds; rigor, livor mortis (settling of blood in the lower portion of the body) and algor mortis (change in body temperature after death)
Scene—condition of furniture, doors and windows, any disturbance or signs of a struggle

30. Classification of Evidence by Nature
Non-mutually-exclusive classifications of Physical Evidence.
Biological
Chemical
Miscellaneous
Physical
Physical
Transient
Pattern
Conditional
Transfer
Associative
Biological—blood, semen, saliva, sweat, tears, hair, bone, tissues, urine, feces, animal material, insects, bacterial, fungal, botanical
Chemical—fibers, glass, soil, gunpowder, metal, mineral, narcotics, drugs, paper, ink, cosmetics, paint, plastic, lubricants, fertilizer
Physical—fingerprints, footprints, shoe prints, handwriting, firearms, tire marks, tool marks, typewriting
Miscellaneous—laundry marks, voice analysis, polygraph, photography, stress evaluation, psycholinguistic analysis, vehicle identification
*Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells.

31. Summary of the Types of Evidence
Testimonial
Biological
Chemical
Miscellaneous
Physical
Physical
Transient
Pattern
Conditional
Transfer
Associative
Indirect (Circumstantial) or
Direct
Testimonial and Physical can be:
More and unique = Increasing probative value
Class or
Individual
Testimonial and Physical can be:
More and unique = Increasing probative value