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

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

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”

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 = ?

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

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

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

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.

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

Testimonial Evidence Tell me again what you saw?

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".

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

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?

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…

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…

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?

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.

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

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

Ronald Cotton Case Study http://www.youtube.com/watch?v=u-SBTRLoPuo http://www.youtube.com/watch?v=I4V6aoYuDcg&featur e=related

Physical Evidence

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

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

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

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

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

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.

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