Types of Evidence “You can observe a lot just by watching” Yogi Berra

Testimonial Statements made under oath by a competent witness Prima facie – direct evidence Examples –Eyewitness –Noises –Knowledge of defendant

Ronald Cotton Testimonial Evidence 1984 – two apts. broken into – women attacked, money stolen Ronald Cotton identified as assailant by two women –Photo –Lineup –ID encouraged by police –Cotton claimed innocence, but…. –Flashlight from Cotton resembled one that was used –Rubber from tennis shoe consistent with Cotton’s –Convicted and sentenced to life + 54 years

10 years later… 1994 – Cotton’s new lawyers filed for DNA testing of evidence No match for Cotton Checked against database Match found = Bobby Poole, convicted felon Witness now speaking out about dangers of eyewitness testimony

Physical Any object or material relevant to a crime Tends to prove some material fact Generally more reliable than testimonial evidence

Types of Physical Evidence Non-biological –Impressions (shoe prints, tire marks) –Firearms and ammunition –Serial numbers –Documents –Residues (explosives, gunshot) –Soil –Audio –E-comm records –Paint chips, glass pieces

Types, continued Biological –DNA –Blood –Hair –Pollen –Bones –Tissues –Other biological fluids (saliva, semen) –Stomach contents –Insects

Circumstantial Implies a fact or event without proving –Hair –Footprint –Blood type –Fibers –Cloth

Value of Physical Evidence Can: 1.prove that a crime was committed 2.back up or refute eyewitness testimony 3.link a suspect with a victim or crime scene 4.determine identity 5.Allow crime reconstruction

Individual vs. Class Evidence Individual - Evidence that can be linked to a unique source 1.Fingerprints 2.DNA 3.Matching pieces of evidence (e.g. glass, clothing, etc.)

Evidence, cont. Class - Not unique; characteristics common to a group of similar objects Most evidence 1.Blood type 2.Fibers 3.Gun type

Associative Evidence Can tie or eliminate a suspect to/from a scene by matching: 1.Blood type 2.DNA 3.Fingerprints 4.Footprints 5.Guns 6.Soil

Class evidence How to increase probative (proof or evidence) value Use probability Example:A student was seen leaving the school parking lot. A car in the parking lot had been broken into and a CD player taken. This student had medium brown hair and had on blue jeans, light-colored sneakers and a dark jacket.

Probability and Class Evidence How many students would be expected to be wearing a dark jacket on any given day? Hypothetical: 5 out of 25 students in your class with a dark jacket - %? How many students would be wearing blue jeans? How many students wearing blue jeans and a dark jacket?

Probability, continued How many students with medium brown hair? How many students with medium brown hair, blue jeans and a dark jacket? How many students wearing light-colored sneakers? How many students wearing light-colored sneakers, blue jeans, medium brown hair and a dark jacket?

Locard’s Exchange Principle When a person comes into contact with an object or another person, cross- transfer of physical evidence can occur The intensity, duration, and nature of the materials in contact determine the extent of the transfer Each contact results in an exchange of materials Trace evidence

Trace Evidence Hair (animal or human) Fibers Skin Soil or plant material (pollen) Fingerprints Shoeprints Body fluids (blood, semen, saliva, mucus) Paint chips, glass chips, chemicals (e.g., drugs)

Wayne Williams Fiber Evidence 12/81 – tried for Atlanta Child Murders 29 children and young adults killed between Conviction largely based on class (fiber) evidence 28 different types of fibers found on several victims matched fibers from Williams home and car Similarities to dog’s hair Preponderance of evidence

Robert Buell 1982, Krista Lea Harrison, 11, abducted, forced into van, raped and strangled Orange fibers found in hair Identified as carpet fiber 28 year old woman, abducted and tortured Escaped and reported abductor (Robert Buell) His van –Matched description of van used for Krista’s abduction –Had orange carpet Unique color Fibers matched those found on Krista Traced to manufacturer Only 74 yds. Shipped to that area (Ohio) Other evidence used in conviction

What if? There is no body There is no obvious physical evidence at the crime scene You don’t know where the crime scene is