1. Crime Scene Investigation & Evidence Collection

2. Lessons from the JonBenet Ramsey Case
In 1996, six year-old JonBenet Ramsey was found murdered in the basement of her home.
This crime scene reveals how important it is for crime scene investigators to secure a crime scene immediately or valuable information may be lost forever.
To this day, the case remains unsolved.

3. Goal of Crime Scene Investigation
Recognize, document and collect evidence
The evidence collected at a crime scene is all investigators have to go on to recreate a picture of what happened at the scene.

4. Principle of Exchange
First described by Dr. Edmond Locard (sometimes called Locard’s Exchange Principle)
Defined as the physical transfer of materials such as hair, fibers, blood, and skin cells when two people come in contact with each other
The longer (or more intense) the contact, the greater amount of trace evidence

5. Types of Trace Evidence
Animal or human hair
Fingerprints
Soil or plant material (pollen)
Body fluids (mucus, semen, saliva, blood)
Fiber or debris from clothing
Paint chips, broken glass, chemicals (drugs, explosives)

6. Types of Evidence
Direct evidence – includes firsthand observations, such as eyewitness accounts or police dashboard video cameras and confessions
Circumstantial evidence – indirect evidence that can be used to imply a fact, but does not directly prove it
- provides a link between a crime scene and a suspect

7. Circumstantial Evidence
Can be physical or biological
Physical evidence– includes fiber, weapons, bullets, and shell casings
Reduces the number of suspects to a specific smaller group of individuals
Biological evidence – includes body fluids, hair, plant parts, and natural fibers
Makes the group of suspects very small, or reduces it to a likely individual
More persuasive in court

8. Class Evidence vs. Individual Evidence
Class evidence – narrows an identity to a group of persons or things (ex.; blood type)
Individual evidence – narrows an identity to a single person or thing (ex.; fingerprints)

9. Crime Scene Investigative Team
Police officers
District attorney
Crime scene investigators, including recorders, sketch artists, photographers, evidence collectors
Medical examiners
Detectives
Specialists (entymologist, forensic psychologist, toxicologist)

10. Analysis of Evidence
Forensic labs process the evidence and send the results to the lead detective
Unlike CSI, lab techs are specialized and only process one type of evidence
Test results lead to crime scene reconstruction

11. Crime Scene Reconstruction
Involves forming a hypothesis of the sequence of events from before the crime was committed through its commission.
Investigators look at evidence and attempt to determine how it fits into the overall crime scenario.

12. Staged Crime Scenes
Create problems for investigators because the evidence does not match witness testimony
Examples of staged crime scenes
Arson
Suicide/murder
burglary

13. Procedure to Use if Staged Scene is Suspected
Initially treat all deaths as homicides
Do the type of wounds match the weapon used
Could the wounds be self-inflicted?
Establish a profile of the victim through family and friends
Evaluate behavior of victim prior to the event
Evaluate behavior of suspects prior to the event
Corroborate statements with evidential facts
Reconstruct the event
Conduct forensic examinations