11 August 2014. Evidence is something that tends to establish or disprove a fact

TYPES OF EVIDENCE11 August 2014

Evidence

Evidence is something that tends to establish or disprove a fact.

Types of Evidence Direct evidence Evidence that establishes a fact without the need for logical inference.

Indirect evidence / circumstantial evidence Evidence that only provides a basis for inference about a fact


Indirect evidence / circumstantial evidence Evidence that only provides a basis for inference about a fact Example: Having a blood alcohol of 0.12 is direct evidence for DUI


Indirect evidence / circumstantial evidence Evidence that only provides a basis for inference about a fact Example: Leaving a fingerprint at the scene of a

crime is indirect evidence … why?

Types of EvidenceDirect or Indirect?

Soil matching a crime location found on a suspect’s clothing

Possession of an illegal substanceVideo of a person committing a crimeFingerprint at crime sceneFingerprints on the murder weapon DNA match to skin under victim’s

fingernails

Types of EvidenceDirect or Indirect?

Soil matching a crime location found on a suspect’s clothing –

Possession of an illegal substance – Video of a person committing a crime -

Fingerprint at crime scene – Fingerprints on the murder weapon –DNA match to skin under victim’s

fingernails –

** Some people argue that only eyewitness accounts are direct evidence**

indirect

indirect

direct

direct?

direct(?)

direct

When could you argue that fingerprints on the murder weapon are direct evidence?

When could you argue that fingerprints on the murder weapon are indirect evidence?

What about skin under the victim’s fingernails? When is it direct? When is it indirect?

Types of Evidence Testimonial evidence - eye witness account Documentary evidence - records

information relevant to a crime Example: audio / video / written documents Physical evidence - any object or material

relevant to a crime

Which type of evidence? DVD stolen from a store Surveillance video of a robbery Crime scene photographs

documentarydocumentar

y

physical

Which kind of evidence is best?

Testimonial evidence is the most direct (it requires no logical inference), BUT it can be very unreliable.

Problems with Eyewitness Accounts

Most cases of wrongful imprisonment are due to mistaken eyewitness identification!



Eye witnesses may be wrong for many reasons: Age / eyesite / hearing / alcohol or drugs



Eye witnesses may be wrong for many reasons: Age / eyesite / hearing / alcohol or drugs Stress / fear can focus and alter perceptions Encounters may be brief or take place under

poor conditions



Eye witnesses may be wrong for many reasons: Age / eyesite / hearing / alcohol or drugs Stress / fear can focus and alter perceptions Encounters may be brief or take place under

poor conditions New information may alter memories (It is much more accurate to ask open-ended

questions than leading ones… i.e. ask what the suspect was wearing, not ‘was he wearing red’.)

How good of an eye witness are you?

Answer the following on paper …

Do you know the person who came in? If not, what was the age/height/weight/race?

What was he/she wearing? When did he/she come in? How long was he/she here? With whom did he/she speak, and what

did he/she say? What did he/she knock over? What did he/she take?

Physical Evidence

Although circumstantial, physical evidence is more reliable than eyewitness accounts.

With enough physical evidence, a strong case can be made.

What can physical evidence show?

It can place a suspect at a the crime scene or with the victim



This is the focus of most investigations. Based on Locard’s Exchange Principle:

“Every contact leaves a trace”

Every time someone goes some where, they leave behind physical evidence, and pick up trace evidence from their environment.



This is the focus of most investigations. Based on Locard’s Exchange Principle:

“Every contact leaves a trace”

Every time someone goes some where, they leave behind physical evidence, and pick up trace evidence from their environment.

Give me an example …



It can help reconstruct a crime (for example, blood splatter can indicate the relative position of two people)

Can guide an investigation / indicate that crime took place (e.g. finding gasoline at a fire indicates arson)

Value of Physical Evidence

The more unique or individualized a piece of evidence is, the better its probative value – the stronger proof it provides.

Example:Finding that a suspect has the same brand of duct tape that was used in a crime is ok evidence.

BUT, if the torn end of the duct tape used in a crime exactly matches the torn end of the suspect’s role, that is much better evidence.

Value of Physical Evidence

Example:A footprint is found at a crime scene. The size matches a suspect, but it’s a common size. How can the print be further individualized?

Describing Evidence

Determine whether each type of evidence listed below is direct or indirect, physical or testimonial. For physical evidence, also describe additional details that might individualize the evidence and/or increase its probative value.

Survelliance camera videotape of a crime Written contract Blood stained clothing Eyewitness account Hair found at the crime scene

Closure

What were our objectives and what did we learn?

How did we address our unit statement? What was our learner profile trait and

how did we demonstrate it?

Exit Ticket

1. What is Locard’s Exchange principle?

Classify each of the following as indirect or direct and as physical, testimonial, or documentary:2. Boot mark3. Eye witness account4. Wire-tap recording 5. Confiscated drugs

Extra credit: what does ‘probative value’ mean?

Homework

Evidence Quiz next class!

Documents

11 August 2014. Evidence is something that tends to establish or disprove a fact