1. DNP -Where would you add the C.S. tape?

2. INTRODUCTION Crime Scene Investigation
FORENSIC SCIENCE
INTRODUCTION
Crime Scene
Investigation

3. CRIME Scene Sequence What Happened? Why Did It Happened? Who Did It?
Evidence Collection
Witness, Suspect and
Motive Development
Investigative Stage
Profiling
Means
Motive
Opportunity
Identification
and Arrest of
Suspect + =
Post Scene
Evidence Processing
Cause, manner, time
of death

4. CORPUS DELICTI “Body of the Crime”
You 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
Sex
Emotion--love, hate, anger
Source of Evidence
Body
Primary and/or Secondary Crime Scene
Suspect(s)

5. FACETS OF GUILT Means--the ability of have committed the crime
Motive--the reason for committing the crime. (This doesn’t have to be proven or presented in a court of law, but its what everyone wants to know.)
Opportunity--time or availability to have committed the crime.

6. Crime Scene Team
A group of professionals investigators, each trained in
a variety of special disciplines.
Team Members
First Police Officer on the scene
Medics (if necessary)
Investigator(s)
Medical Examiner (if necessary)
Photographer and/or Field Evidence Technician
Lab Experts (see Forensic Career Matching sheet for examples)

7. The Seven S’s of Crime Scene Investigation
Secure the scene.
Separate the witnesses.
Scan the scene.
Seeing the scene. (Photographing the scene properly)
Sketch the scene.
Search for evidence.
Secure the collected evidence.

8. Basic Stages at a Crime Scene These are the responsibility of the 1st Officer:
Approach, secure and protect the scene
Initiate preliminary survey/determine scene boundaries
Only authorized personnel should be allowed on the scene (Every person who enters the scene is a potential contaminator of viable physical evidence)
Once a scene is secured, the lead investigator duties:
Evaluate physical evidence possibilities
Prepare narrative description
Depict scene photographically
Prepare diagram/sketch of scene
Conduct detailed search
Record and collect physical evidence
Conduct final survey
Release scene

9. What’s involved with Photography?
The scene should be photographed in an unaltered condition. Unless someone is injured, everything should be left in its unaltered condition.
Close-up of phys. evidence should include a ruler or something to show size/scale
Videotaping can be done but still photography is still the best for detail
WHAT to photograph?
Area of crime
Adjacent areas
Entrance/exit
Body if present -- area under body after removal
injuries/ weapons

10. Sketching the Scene
After photos, sketch… first rough sketch is made at the scene with these details in mind:
Accurate depiction of the dimensions at the scene
Location of important objects to the case
TRIANGULATION METHOD – measured accurately
Etc…we will cover this topic in more detail later!!!
( The finished sketch is drawn to scale using the measurements provided in the rough sketch and is used as court evidence)

11. Prepare to Collect Evidence!
The best search options are typically the most difficult and time consuming
You can not “over document” the physical evidence.
There is only one chance to perform the job properly
There are two basic search approaches:
A “cautious” search of visible areas, taking steps to avoid evidence loss or contamination
After the “cautious” search, a vigorous search for hidden/concealed areas.

12. The Search….
A search must always be thorough and systematic (even if a suspect is guilty!)
Methods of search are always customized to suit the crime. (Ex. Large open area uses a line search with a few people)
Here are some factors that help determine the type of search method:
- Locale and size of area
- # of techs available
- size/type of evidence

13. Crime Scene Search Patterns
Strip or Line
Quadrant or Zone

14. Crime Scene Search Patterns
Spiral
Grid

15. Collecting Evidence…
The collection of evidence starts with the most fragile or most easily lost evidence.
Photographs are continually taken.
Most items are placed in paper envelopes or bags.
Any liquid, arson evidence, or moist evidence are packaged differently, not in paper bags.
Items are always packaged separately to eliminate cross-contamination.
Proper labeling must always be place on ALL packages!

16. Chain of Custody
In order to present credible evidence in court, a chain of custody log is essential.
Every person who handles the evidence must be accounted for and can be called upon in court.
Each evidence log contains the following:
- Collector’s initials
- date of collection
- Location
- Record of a transfer whenever it occurs,
which should be kept to a minimum

17. WHAT GOES TO THE LAB?
Physical evidence must be collected in such a way that prevents any change between the crime scene and the crime lab.
Victim’s clothing- never in an airtight container.
Fingernail scrapings
Hairs- leave on the article and send entire article to lab, where they will remove the hair
Blood- leave on the article and send entire article to lab, where they will remove the blood
Never in an airtight container, because the condensation could cause mold growth which could destroy the evidence.
Fibers- leave on the article and send entire article to lab, where they will remove the fibers
Swabs of secretions
Charred debris- should be packaged in an air-tight container, so the petroleum residues do not evaporate. (paint cans)
Bullets
Hand swabs if needed
NOTE: Each different item must be packaged separately! (prevent cross contamination)

18. Analyze the Evidence… The lab results can: Finally:
Show how reliable any eyewitness accounts are.
Establish the identity of suspects and/or victims.
Show suspects to be innocent or link them with a scene or victim.
Finally:
The facts of the case are determined when the forensic lab processes all the collected evidence.
The lab then sends the results to the lead detective who aims to see how it all fits into the crime scenario.

19. Just A Thought…
It’s not what you know that hurts you, its what you think you know and it’s not so Mark Twain
How does this apply to forensic science and crime investigations?

20. “Drawing to Scale” #1 – What is the scale for your final drawing?