1. Crime scene investigation

2. Locard’s Exchange Principle
Locard’s Principle is the reason for investigation of a crime scene.
It is impossible for a criminal to act without leaving traces of this presence.
With contact between two items, there will be an exchange

3. crime must occur before a person can be convicted of the crime.
Must prove:
that a crime occurred
that the person charged with the crime was responsible for the crime
Must determine:
Primary Crime Scene
Secondary Crime Scene(s)
Must Identify Source(s) of Evidence
Victim’s Body
Primary and/or Secondary Crime Scene
Suspect(s) Body

4. Crime Scene Primary Crime Scene – location where the crime took place
Example: Bank where armed robbery took place
Secondary Crime Scene – additional locations which are related to the crime and may provide some measurable amount of physical evidence
Example: Get away car and garage where car was found

5. Crime Scene Investigation
Chapter 3
Crime Scene Investigation
Involves 4 Steps:
Recognition—scene survey, documentation, collection
Identification—classification of evidence
Individualization—comparison testing, evaluation, and interpretation
Reconstruction—sequencing events, reporting, and presenting
Kendall/Hunt

6. Testimonial (Direct evidence)
Types of Evidence
Testimonial (Direct evidence)
firsthand observations:
eyewitness accounts
dashboard video cameras
confessions

7. Types of Evidence Circumstantial (indirect evidence)
used to imply but not prove a fact
may link a suspect and a crime scene
ex. Suspect’s gun found at crime scene
Physical:
Impressions, fibers, weapons, bullets, shell casings
reduces number of suspects to group
Biological :
may make group of suspects very small or even one individual
Body fluids, hair, plant parts, natural fibers

8. Crime Scene Investigation Team:
Police Officers: usually first at the scene
Recorder (notetaker)
Photographers
Sketch artist
Crime Scene Investigators: document the crime and collect physical evidence
Evidence Technicians: aid in collection and packaging the crime scene evidence
Medical Examiners: may be necessary to determine cause of death in a homicide case
Detectives: look for leads, interview witnesses and talking to the CSI about evidence
Specialists: entomologists, psychologists, etc…

9. First Officer on the Scene
Chapter 3
First Officer on the Scene
To an officer
A Assess the crime
scene and assist the
injured – Safety 1ST priority
D Detain the witness
A Arrest the perpetrator
P Protect the crime scene
T Take notes
ADAPT means
Kendall/Hunt

10. First Officer on the Scene
Observe persons and vehicles near the scene as well as smells and sounds
Note the time, address and weather conditions
Conduct a brief walk through of the scene and determine if medical assistance is necessary
Call for CSI
Secure and Isolate the scene- must establish perimeter security especially to control the media

12. The Note Taker
The note taker should record everything that happens during the crime scene investigation.
The notes should include
the location & weather,
type of crime, time of discovery, & name of discoverer
the date, times and names for anyone entering or exiting the crime scene.
Make notes in ink, with pages numbered sequentially.
Make notations in chronological order.

13. The photographer…
The first photographs that are taken should show an overview of the scene from many different perspectives followed by close up photos of individual pieces of evidence.
Can never take too many photos of a crime scene. There may be shots taken from every possible angle of view.
Victims and evidence must not be moved until they have been photographed from all necessary angles.

14. The Photographer
The evidence technicians will place markers and rulers next to the evidence before the photographer will photograph the evidence
Physical evidence is photographed with a ruler to show it’s size and also it’s location relative to the entire scene.
Photographer must keep a photo log of all pictures taken

15. The Police Artist
The police artist is responsible for the crime scene sketch.
A rough sketch is drawn at the scene and the final sketch is created at the police station

16. The Sketch
A sketch provides accurate measurements and distances between objects.
The final sketch is drawn to scale using templates, etc.

17. Other responsibilities of the sketch artist include…
Creating composite drawings of any suspects
These composites may be drawn by hand or computer generated

18. The Medical Examiner
When a victim is deceased, the Medical Examiner or a representative from the ME’s office will be responsible for retrieving the body from the scene.
Photographs and a body temperature will be taken.
The hands may be bagged and then the body is placed into a clean body bag.

19. The Detective will… 2. Take statements
1. Interview witnesses
2. Take statements
3. Verify the truth of the statements
4. Determine the motive, means and opportunity for each suspect
5. Seek additional information
6. Charge and arrest suspects
7. Testify in court.

20. Evidence Technicians Sets up numbers at the pieces of evidence
Obtains the necessary equipment for collecting and packaging evidence
Properly collects all evidence

21. COLLECTING AND PACKAGING EVIDENCE
Each item must be placed in a separate container, sealed, and labeled
Most fragile is collected and packaged first
Different types of evidence require specific or special collection and packaging techniques
The body is the property of the coroner or medical examiner. The collection of evidence on the body is done by that department

22. PACKAGING
Most items should be packaged in a primary container and then placed inside a secondary one.
These are then placed inside other containers such as paper bags, plastic bags, canisters, packets and envelopes depending on the type and size of the evidence.

23. CHAIN OF CUSTODY who have had possession of an item of evidence.
There must be a written record of all people
who have had possession of an item of
evidence.
The evidence container must be marked for identification
The collector’s initials should be placed on the seal
If evidence is turned over to another person, the transfer must be recorded.