1. Crime Scene and Evidence
Collection

2. Vocabulary to Know First responder Individual evidence Paper bindle
Primary crime scene
Secondary crime scene
Trace evidence
Direct evidence
Chain of Custody
Circumstancial evidence
Class evidence
Crime scene investigation
Crime scene reconstruction

3. Types of Trace Evidence
Hair
Fibers
Skin cells
Pollen
Glass fragments
Paint chips
Makeup, etc.

4. Classifying Evidence Direct Evidence: Circumstancial evidence:
1st hand observations; eyewitness video.
Circumstancial evidence:
Indirect evidence implies fact but doesn’t prove.
2 types – physical and biological

5. Classifying Evidence - Circumstancial
Also called Indirect Evidence
Physical
Impressions
Fingerpints, shoeprints, tire prints,tool marks.
Synthetic fibers
Shell casings
Bullets
Weopons
Biological (more pursuasive)
Body fluids
Hair
Plant parts
Natural fibers
Blood

6. Classifying Evidence Class Evidence
Place evidence into groups. Make or model or objects
Individual Evidence
Place evidence to an individual person or thing.

7. Let’s Do a Lab Can Evidence be Individualized?
Purpose: to determine whether pieces of evidence are class or individual evidence.
Procedure:
Separate into groups of two. Each group go to a lab table. 1-15
Rotate through the scenarios until you have completed all.
Time: 3 each table
Expectations:
Work only with your lab partner. Do not move through groups.
Stay at your current lab table until told to rotate.
I will know you are participating by you being actively engaged in the lab.
Failure to follow lab safety and the above expectations will result in 3 point deducted off each lab members grade.

8. Locard’s Exchange Principle
Established by
Dr. Edmond Locard
Director of 1st forensic lab in Lyon, France.
States: when a person comes in contact with an object or another person, a cross-transfer of physical evidence occurs. The evidence is known as trace evidence.
"It is impossible for a criminal to act, especially considering the intensity of a crime, without leaving traces of this presence."

9. CSI (Crime Scene Investigation)

10. CSI Team Police officers CSI ME (medical examiner) Detectives
Recorders, sketch artists, photographers, evidence collectors.
ME (medical examiner)
Detectives
Specialists
Entomologist, psychologists, anthropologists

11. 7 S’s of CSI Secure crime scene Separate witnesses Scan scene
Seeing the scene
Sketch the scene
Searching for evidence
Securing and collecting evidence

12. 7 S’s: Secure the Crime Scene
Done by 1st responder
Restrict all unauthorized persons from entering cs.
Keep security log of all who visit cs.
Keep evidence from getting contaminated.

13. 7 S’s: Separating Witnesses
Keep witnesses from comparing or creating a story (collusion).
Ask each witness the following ?’s.
when did the crime occur?
Who called in the crime?
Who is the victim?
Can the perp. be identified?
What did you see happen?
Where were you when you observed the crime?

14. 7 S’s: Scanning the Scene
Scan scene to determine where photos need to be taken.
May occur at both primary & secondary cs.

15. 7 S’s: Seeing the Scene CS examiner must see (observe) the scene.
Photos must be taken w/ & w/o measuring ruler.
Triangulation of stationary obj. should be included as reference pts.
View cs from several different angles.

16. 7 S’s: Sketching the Scene
Rough Sketch
Should include:
Position of any evidence or victim.
All objects measured from two stationary landmarks
North labled
Scale of distance provided
Any objects in vicinity of cs. (doors, windows, furniture)
If outdoors, position of trees, vehicles, hedges, and other structures should be included.
Final Sketch
Very accurate; could be used in court.
In addition to RS include:
Case #
Date
Location
Name

17. Sketch Examples

18. 7 S’s: Searching for Evidence
Search patterns:
Grid
Linear
Quadrant or Zone
Spiral
Single investigater may use grid, linear or spiral.
Group – linear, zone or quadrant.
Flashlight & forceps are equipment of choice. Keeps from picking up extraneous materials.

19. Types of Search Patterns

20. 7 S’s: Securing & Collecting
Must be properly packaged, sealed & labeled
Packaging Examples:
Liquids & arson: stored in airtight, unbreakable containers
Most biologicals: breathable containers so evidence can dry out – reduces chance of mold contamination. Package in paper bindles.
Once proper containers are used, place in plastic or paper container. Then:
Seal with tape.
Label across tape by collector
Evidence log & chain of custody attached to evidence container.

21. 7 S’s: Securing & Collecting
2. Evidence Log includes:
Case #
Item inventory #
Description of evidence
Name of suspect
Name of victim
Date & time of recovery
Signature person recovering evidence
Signature of any witness present during collection.

22. 7 S’s: Securing & Collecting
3. Packaging Evidence
Choose appropriate size sheet of clean paper for bindle.
Crease paper in grid pattern
Place evidence in center grid
Fold in left then right sides
Fold over top & bottom
Insert top flap into bottom flap & tape closed.
Place bindle inside plastic/paper bag. Fold bag closed.
Place seal over folded edge of evidence bag.
Collector writes name over folded edge.
Remember: large, wet object should be placed in paper container & sealed to allow for air drying.
Control samples must also be taken from victim for the purpose of exclusion.

23. Chain of Custody *Very Important*
Tech opens packaging at some other location except where originally sealed.
After examination, evidence is repackaged in original container where it was removed & placed in a new package.
Seal new packaging with techs signature on seal.
Tech also signs chain of custody log attached to package.
Individual that finds the evidence marks it for identification & bags evidence in plastic/paper container.
Placed in final container & labeled with pertinent info.
Container is sealed & collectors signature across sealed edge
Pass onto person that will transport to lab who signs it over to technichian.

24. Analyzing Evidence Crime Scene Reconstruction
Crime scene reconstruction completed using evidence (before crime to its completion)
Evidence used to co-oberate witness accounts
Direct evidence more compelling than circumstancial.
Staged Scenes
Poses unique problems. Evidence doesn’t match witness testimony.
Common staging situations.
processed by tech that specializes in specific areas of forensic science
Evidence results sent to lead detective

25. Staged Crime Scene