 Evidence : Something that tends to establish or disprove a fact.  Examples of evidence: › Documents › Testimony › Other objects

 Testimonial vs. Physical Evidence  Testimonial: what is said in court by a competent witness; also called direct evidence or prima facie evidence  Physical: tangible items that tend to prove some material fact; also called real evidence.

 Eyewitness accounts can provide important evidence leading to the arrest of a criminal.  Juries are HEAVILY influenced by eyewitness identification.  QUESTIONS: How accurate are eyewitnesses? What might influence their accuracy?

 Eyewitnesses can make perceptual errors for many reasons: › Crime scene could have been dark › Encounter could have been very brief › Weapon could have diverted with witnesses attention  Errors in the memory process are very common!  TIME is a huge factor! › Time between the actual event and questioning

 What could lead someone to say something?  Could seeing someone who looks like someone affect recall from memory?  Could a person persuade someone to say something this is untrue? How?

 Police must be very careful in choosing an eyewitness who is reliable…which is hard to tell from a few questions  Important points to consider: › What type of crime and what was seen › Serious crimes vs. not so serious crimes › Age of eyewitness and affected memory › Interviewing techniques and retrieval of information

 What type of crime and what was seen › Witnesses more likely to accurately remember characteristics such as sex and hair color, more than age, height, and specific race.  Serious vs. not so serious crimes › Victims of serious crimes are more likely to remember every detail because they relive the incident often. › Weapons/threats tend to sharpen focus and make information more easy to recall. › Any kind of stress tends to narrow focus.

 Age of eyewitness and affected memory › Children tend to not remember as well as adults. Accuracy of child = interviewing technique. › Older adults have poorer eyesight and hearing which could affect memory and make the information less accurate. › Learning disabilities, mental disorders, alcohol, drugs, or head injuries weaken memory and make recall difficult.

 Interviewing techniques and retrieval of information › Research shows that eyewitnesses answer questions better about the situation than what a person looked like. › Open-ended questions will provoke better responses  What was the offender wearing? Vs. What color was the offender’s shirt?  Avoid leading questions: Was the offender’s shirt red? These questions limit accuracy.

 Other factors to consider: › Did the witness know the accused and what kind of relationship was established? › How much time has passed between the offense and the identification? › Has the witness already identified/failed to identify the defendant? › Has the witness identified someone else?

 Most known cases of an innocent person being convicted happened because of a mistaken eyewitness identification.

 Most interested in physical evidence because it is “physical”! You, as a scientist, can put your hands on it!  Physical evidence takes on many forms because it is virtually unlimited. Some examples: › Something as large as a building › As fleeting as an odor › As small as a hair › Or submicroscopic, such as DNA evidence

 Much more reliable than testimonial evidence  Indirect evidence : evidence that does not prove a fact; most evidence  Circumstantial evidence : evidence that implies a fact or event without actually proving it. (The more the better!) › Possession of a controlled substance › Driving under the influence

 Value of Physical Evidence: › Can prove a crime has been committed and set the scene for the investigation › Back up a witness testimony or prove it false › Can link a suspect with a victim or with a crime scene › Can determine the identity of people associated with a crime › Can allow investigations to reconstruct a crime

 Role of the Forensic Scientist and Physical Evidence: › Collect and submit physical evidence for testing in a lab setting › Determine links between the evidence, the victim, the crime scene, and the suspect › Determine if collected evidence is relevant to the crime

 Testing Physical Evidence  Unknown/questioned evidence : material that has been collected from a known location but is of unknown origin  Known/control evidence : material that comes from a proven or known source  Once samples are all known, it is important for forensic scientists to reconstruct the crime scene so they can form a more accurate opinion of what happened/answer questions about events.

 When reconstructing the scene, this allows for all physical evidence to be put into a proper place and prove its relevance to the investigation.  Reconstruction uses the forensic scientists, crime scene investigators, detectives and other law enforcement officers, and medical examiners.

 The best evidence is that which can be linked to a unique, single, specific source; Individual evidence. › Fingerprints, handwriting, DNA patterns, or sometimes physical matches like broken glass  Most evidence is considered class evidence, which means it is associated with a common group of items. › Blue jeans, tennis shoes, etc.

 To prove probative value (the ability of evidence to prove something that is material to a crime), forensic scientists must find as many different types of objects as possible to link the suspect to the crime. › Dirt on a shoe, glitter on a pair of jeans, etc.