1. Crime Scene Investigation

2. Arriving at a Crime Scene
A crime scene is the site where the offense took place
When officers first arrive at the crime scene, they have three takes to perform:
Assist the injured
Call reinforcements to eliminate hazards
Search crime scene for perpetrators

3. Beginning a Police Investigation
Once the crime scene is considered safe can an investigation begin
The Crown’s success in prosecuting offenders often depends on physical evidence
Two boundaries must be accurately established by police:
The Centre
The Perimeter

4. Establishing a Crime Scene
The perimeter are the areas surrounding the center, where the offender may have been present or may have left evidence
The center is the area where the offence was actually committed

5. Establishing Crime Scenes
Crime scenes are preserved for three reasons:
Allow for a thorough search of the scene
Seize and collect physical evidence
Ensure seized physical evidence is admissible in court

6. Establishing Crime Scenes
If evidence at a crime scene is not properly managed, it can become contaminated
This is the loss, alteration, or destruction of physical evidence

7. Physical Evidence
Physical evidence is any object, impression, or body element used to prove or disprove facts
Physical evidence contains greater weight in court than evidence gained through witness statements

8. Physical Evidence
What will evidence collected at a scene do for the investigation?
May prove that a crime has been committed
Establish any key elements of a crime
Link a suspect with a scene or a victim
Establish the identity of a victim or suspect
Corroborate verbal witness testimony
Exonerate the innocent

9. Physical Evidence
What will evidence collected at a scene do for the investigation?
May prove that a crime has been committed
Establish any key elements of a crime
Link a suspect with a scene or a victim
Establish the identity of a victim or suspect
Corroborate verbal witness testimony
Exonerate the innocent

10. Tools are the most frequently used when crimes are committed
Physical Evidence
Tools are the most frequently used when crimes are committed
Tools will often have individual characteristics on their surfaces or edges

11. Physical Evidence
Impressions are patterns or marks found on various surfaces
Police will first photograph, scan, or make a mould of the impression
Investigators will then try to match the impression with the object that made it

12. Physical Evidence Impressions will have two characteristics:
Class Characteristics are the general attributes of an object
Individual Characteristics refer to specific and unique features of an object

13. Physical Evidence
Visible fingerprints can be observed by the human eye and photographed because the fingertip was coated in blood or some other substance

14. These are not visible to the human eye
Physical Evidence
Latent fingerprints are formed when the natural oils and perspiration on the fingertip come in contact with objects
These are not visible to the human eye

15. Physical Evidence
Shoe and tire marks can be matched to the suspects shoes and tires to help place him at the scene of the crime

16. Broken objects separated during a crime can be placed back together
Physical Evidence
Broken objects separated during a crime can be placed back together
Gloves, like fingerprints, will still leave the impression’s class characteristics on surfaces

17. Physical Evidence
Bodily fluids found at crime scenes can be used for DNA testing or other laboratory testing
Hair and clothing fibers can easily be transferred from offender to the victim during a crime

18. Procedures for Labelling Evidence
Crime scene officers label and photograph evidence so it can be identified at a later date

19. Procedures for Labelling Evidence
Exact measurements are taken of the evidence found within a crime scene

20. Procedures for Labelling Evidence
A detailed map of the crime scene is drawn to scale identifying where all evidence was specifically located

21. Procedures for Labelling Evidence
All evidence collected is tagged and placed in an evidence package
Includes a brief description of the item, case number, date collected, and location of collection

22. Chain of Custody
A chain of custody is the witnessed, written record of the people who maintained unbroken control over an item
The date and time, the circumstances in which the evidence was handled, and what changes, if any, were made to the evidence