1. Criminal Evidence Chapter 3
Processing the Crime Scene

2. Chapter Objectives Describe the preliminary investigation.
Identify types of crime-scene evidence.
Summarize the responsibilities of the first responding officer.
Explain how to secure and protect the crime scene.
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3. Chapter Objectives
Explain how to collect and search for evidence at the scene.
Explain how to properly perform a follow-up investigation.

4. Describe the preliminary investigation.
Learning Objective 3.1
Describe the preliminary investigation.

5. The Preliminary Investigation
Responsibilities of officers responding to the scene include:
Being prepared to inform superiors of their findings
Assisting victims
Securing and protecting the crime scene
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6. The Preliminary Investigation
Responsibilities of officers responding to the scene include:
Apprehending the perpetrator
Collecting and preserving evidence
Interviewing witnesses
Performing other necessary operational functions

7. Identify the types of crime-scene evidence.
Learning Objective 3.2
Identify the types of crime-scene evidence.

8. Types of Evidence Locard exchange principle
Transfer of evidence theory
"Every contact leaves a trace."
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9. Types of Evidence Two commonly used classifications Corpus delicti
Evidence that establishes a crime has been committed
Associative evidence
Links a suspect with a crime
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10. Types of Evidence Physical Direct or prima facie
Indirect or circumstantial
Testimonial
Trace
Demonstrative

11. Summarize the responsibilities of the first responding officer.
Learning Objective 3.3
Summarize the responsibilities of the first responding officer.

12. Responsibilities of First Responding Officer
Actions en route to the crime scene
Alert for possible presence of perpetrators or perpetrators' vehicles fleeing from the scene.
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13. Responsibilities of First Responding Officer
Initial actions upon arrival
Verify crime has been committed.
Conduct a protective search if exigent circumstances determine the need to enter a building.
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14. Responsibilities of First Responding Officer
Assist victims and protect witnesses and bystanders.
Arrest the perpetrator.
Probable cause or an arrest warrant issued
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15. Responsibilities of First Responding Officer
Follow-up communication
Identification of witnesses and vehicles
Briefing investigators and superiors
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16. Responsibilities of First Responding Officer
Information included in the broadcast of a flash description
Type, location, and time of crime occurrence
Number of suspects involved
Physical description of those involved
Weapons used
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17. Responsibilities of First Responding Officer
Information included in the broadcast of a flash description
Direction last observed proceeding and time
Means of escape
Injuries of anyone involved
Vehicles used

18. Explain how to secure and protect the crime scene.
Learning Objective 3.4
Explain how to secure and protect the crime scene.

19. Securing a Crime Scene Define the crime scene area.
Request backup to help restrict access to the crime scene and control onlookers.
Clear the interior of the crime scene.
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20. Securing a Crime Scene Record actions previously taken at the scene.
Restrict access to the scene.
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21. Securing a Crime Scene
A scene "walk-through" will be conducted by the investigator to get an overview of the entire scene.
A chain of custody will be established for all evidence.
Identify resources needed to assist with the investigation.

22. Explain how to collect and search for evidence at the scene.
Learning Objective 3.5
Explain how to collect and search for evidence at the scene.

23. Evidence Search and Collection
Objectives of evidence discovered at the crime scene
Determine the facts of the crime.
Identify the lawbreaker.
Aid in the arrest of the perpetrator.
Aid in the criminal prosecution of the perpetrator.
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24. Evidence Search and Collection
Phases of crime scene search
Surveying the crime scene
Documenting with sketches and photographs
Recording all physical evidence
Searching for fingerprints
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25. Evidence Search and Collection
Crime scene search patterns
Spiral search method
Grid search method
Strip or line search method
Quadrant or zone search method
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26. Evidence Search and Collection
Collect the most fragile evidence first.
Search the crime scene a second time after the evidence has been collected.
One investigator should be designated as the evidence collector.
Mark evidence immediately.
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27. Evidence Search and Collection
Court admissibility
Legally seized
Integrity of chain of custody
Properly packaged and marked

28. Explain how to properly perform a follow-up investigation.
Learning Objective 3.6
Explain how to properly perform a follow-up investigation.

29. Follow-up Investigation
Tasks of follow-up investigator include:
Contacting the medical examiner
Conducting a neighborhood canvass
Preparing crime-scene reports
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30. Follow-up Investigation
Performance of the follow-up investigation
Analyze reports of officers conducting preliminary phases of the investigation.
Review official reports.
Gather information on family and associates of suspects.
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31. Follow-up Investigation
Performance of the follow-up investigation
Examine the victim's background.
Check police intelligence files to develop potential suspects.
Organize police actions, such as neighborhood canvassing, raids, and search warrants.

32. Chapter Summary
The term preliminary investigation is defined as an initial inquiry by officers to establish facts and circumstances of a suspected crime and preserve any evidence related to that crime.
Crime-scene evidence is dynamic, and protection and preservation of the scene are crucial.
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33. Chapter Summary
The initial response to a call by the responding officer is a critical phase of any criminal investigation.
An important function of responding officers is to ensure neither their actions nor actions of others will unnecessarily disturb the crime scene.
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34. Chapter Summary
After an investigator has properly documented a crime scene, the actual search must begin.
The investigator's duties do not end at the crime scene.