1. Crime Scene Investigation & Evidence Collection
Unit 2
Crime Scene Investigation & Evidence Collection
“The wise forensic investigator will always remember that he must bring all of his life experiences and logic to find the truth. This means common sense, informed intuition, and the courage to see things as they are. Then he must speak honestly about what it adds up to.”
Dr. Henry Lee
Chief Emeritus for Scientific Services for the State of Connecticut

2. The Goal of Crime-Scene Investigation
To recognize, document, and collect evidence at the scene of a crime.

3. Corpus Delicti “body of the crime”
Authorities must prove:
That a crime occurred
That the person charged with the crime was responsible for the crime
Top reasons for committing a crime
Money
Revenge
Emotion—love, hate, anger
Source of evidence
Body
Primary and/or secondary crime scene
Suspect(s)

4. Locard’s Exchange Principle
When a person comes in contact with an object or another person, material can be transferred.
More intense interactions result in greater exchange.
Transferred material is known as trace evidence.

5. Trace Evidence

6. Types of Evidence Direct evidence – Firsthand observations
Examples: eyewitness accounts, video, etc.
Circumstantial evidence – Indirect physical or biological evidence that can link a person to a crime, but don’t directly prove guilt.
Physical examples: bullets, weapons, fibers, tool marks, etc.
Biological examples: body fluids, hair, plant parts, etc.

7. The Crime-Scene Investigation Team
Police Officers
Crime-Scene Investigators
Recorders
Sketch artists
Photographers
Evidence Collectors
Medical Examiners
Detectives
Specialists

8. Crime Scene Investigation
Chapter 3
Crime Scene Investigation
Based on the scientific method, the Locard Exchange Principle, logic, and forensic techniques
Involves a very important, very precise set of steps
Goal: Find Physical Evidence!!!
Kendall/Hunt

9. The Seven S’s of Crime Scene Investigation: SECURE the scene
1. Securing the Scene
Responsibility of the first responder
Restricts entrance to scene
Starts log of all persons entering
May send for additional experts or officers

10. The Seven S’s of Crime Scene Investigation: SEPARATE witnesses
2. Separate and question the witnesses –
When did the crime occur?
Who called it in?
Who is the victim?
Can the perpetrator be identified?
What did you see happen?
Where were you when you observed the crime scene?

11. The Seven S’s of Crime Scene Investigation: SCAN the scene
Scanning the Scene-
Determine where photos should be taken
Determine if the location is a primary crime scene (where the crime occurred), or a secondary location (such as where a body was moved to).

12. The Seven S’s of Crime Scene Investigation: SEEING (record) scene
4. Seeing the Scene – (record the scene)
Take photos, including close-up pictures with and without rulers for scale.
Digitize scene if possible.

13. The Seven S’s of Crime Scene Investigation: SKETCH
Sketching the Scene –
Drawn to scale
All objects should be measured from two immovable objects
Direction of north should be included
Scale of drawing, date, and location should be included.

14. Crime Scene Sketch

15. The Seven S’s of Crime Scene Investigation: SEARCHING
Searching for Evidence-
Tools such as flashlights, UV lights, or vacuums may be used.
Investigators walk patterns to avoid missing anything.
Must be SYSTEMATIC and IMMEDIATE
Investigator in charge is responsible
What to search for is determined by the circumstances of the crime
How to search (the search pattern) depends on size and location of scene, and number of searchers

16. Crime Scene Search Patterns

17. Line/Strip Method
Line or strip method-best in large, outdoor scenes

18. Grid
Basically a double-line search; effective, but time-comsuming

19. Zone
Most effective in houses or buildings; teams are assigned small zones for searching

20. Spiral
May move inward or outward; best used where there are no physical barriers

21. The Seven S’s of Crime Scene Investigation: SECURE evidence
7. Securing and Collecting Evidence –
Liquids and arson remains are stored in airtight, unbreakable containers.
Biological evidence is placed in a breathable container to dry.
After drying, biological evidence is transferred to a paper bindle and sealed in a bag.

22. Evidence Log An evidence log is completed listing:
case number (dateyearcase#__ =dec. 01, 2014)
item inventory number
(case number-evidence# ___ , )
description of evidence
name of suspect
name of victim
date and time of recovery
signature of person recovering evidence
signature of witnesses to collection

23. Chain of Custody

24. Legal considerations
Search and removal of evidence must be done according to the 4th amendment:
“ The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized”

25. Warrantless Search Existence of emergency circumstances
Need to prevent immediate loss or destruction of evidence
Search of person/property made incident to lawful arrest
Search made by consent of involved parties
Plain view doctrine
Circumstances defined by Supreme Court

27. Medical Examiner and Coroner
Medical Examiner: medical doctor (usually a pathologist) appointed by the governing body of the area
Coroner: elected official who usually has no special medical training
In four states, the coroner is a medical doctor

28. Responsibilities of Medical Examiners
Identify the deceased
Establish the time and date of death
Determine a medical cause of death (the injury or disease that resulted in the person dying
Determine the Mechanism of death (the physiological reason the person died
Classify the Manner of death (natural, accidental, suicide, homicide, undetermined)
Notify the next of kin

29. Analyze the Evidence
After a crime-scene investigation, forensic lab work begins.
Test results lead to a crime scene reconstruction.
Test results can be used to identify staged crime scenes.