1. Crime Scene Investigation
The 7 S’s of Crime Scene Investigation

2. 1. Securing the Scene
First responding officer – it is their duty to secure the scene by limiting access to the scene and preserve scene with minimal contamination
1st priority – Secure safety of all individuals in the scene by limiting access to crime scene
2nd priority –Preservation of evidence
3rd priority – Witnesses must not be allowed to talk to each other to avoid collusion (creation of story by witnesses talking to each other)
*****Locard’s Principle*****
Contact between individuals and locations leads to an exchange of evidence
REMEMBER – “Every Contact Leaves a Trace”

3. EMS – “Emergency Mutilation Services”
Who is a 1st Responder?
Police, Fireman, EMS
CSI are typically the last to arrive
EMS – “Emergency Mutilation Services”

4. 1.Securing the Scene
First officer on scene responsibilities – check list:
Secure safety of individuals at the scene
Approach scene cautiously (look, listen, smell)
Obtain medical attention for anyone injured
Call in backup help, including medical and CSI personnel
Separate witnesses
Perform initial walk-through (scan the scene)
Search scene briefly to notify lab of equipment needed
Collect information, including address/location of the scene, time date, type of call, names and addresses of all parties involved and present
Securing integrity of the scene by establishing boundaries of the scene and setting tape around parameter
Protect crime scene by remaining alert and attentive
Document the entry and exit of all authorized – Use a security log
Provide brief update to the “next-in-command” officer on scene

5. 2. Separating the Witnesses
3rd priority – Witnesses must not be allowed
to talk to each other to avoid collusion (creation of story by witnesses talking to each other)
NOTE: CSI do not question/interrogate witnesses/suspects. This is the job of detectives/police!
Questions to ask:
When did crime occur?
Who called in the crime?
Who is the victim?
Can the perpetrator be identified?
What did you see happen?
Where were you when you observed the crime scene?

6. Not all crimes begin and end at same place
3. Scanning the Scene
Scan the scene to:
1. Determine where to take photos
2. Determine primary crime scene
3. Determine secondary crime scene
(if this applies to the case)
Not all crimes begin and end at same place

7. 4. Seeing the Scene Examiner needs: Photos of overall area
Close-up photos with and without measuring ruler
Photos of triangulation of stationary objects
Photos taken from different angles and distances
Several close-up photos of any evidence and human remains

9. 5. Sketching the Scene
A rough sketch of the scene is made noting – position of body (if any) any other evidence
Sketch should include:
Objects measured from 1 immovable landmarks (Datum Point)
North should be labeled
Scale of distance should be provided
Objects in the vicinity of the scene should be included
Indoors: doors, windows, furniture, etc
Outdoors: trees, vehicles, hedges, etc

11. 5. Sketching the Scene
Final Sketch – Done later more accurate copy used in court proceeding computer programs can be used Should include: North Scale Case # Date Location Name of officer/investigator

12. 6. Searching for Evidence
Searching for evidence should be systematic
Type of Searches:
Spiral
Grid
Linear
Quadrant or Zone

14. Aerial Search – Inaccessible

15. 6. Searching for Evidence
The type of search depends on:
Area of the crime scene
Number of investigators present
The location of evidence should be:
Marked
Photographed
Sketched
Most common search pattern, in large areas if plenty of people are available is the GRID search pattern.

16. 7. Scene Evidence Collection
Evidence needs to be – properly packaged sealed and labeled.
1. Liquids and arson (fire) – stored in airtight
unbreakable containers
2. Biological evidence – stored in breathable
containers for evidence to dry out to reduce mold growth

17. 7. Scene Evidence Collection Con’t
Biological evidence –
1. Needs to dry out in breathable container
2. Is stored in paper bindle (druggist’s fold)
3. Placed in plastic (must have air holes) or paper container
4. Is sealed w/tape
5. Collector signs his/her name – Chain of Custody

18. 7. Scene Evidence Collection Con’t
An evidence log and chain of custody document must be attached to the evidence container
Evidence log should contain:
Case #
Item inventory #
Description of evidence
Name of suspect
Name of victim
Date and time of recovery
Signature of person recovering evidence
Signature of any witness present during collection

19. 7. Scene Evidence Collection
Packaging Evidence:
Choose appropriate-size sheet of clean paper for bindle
Crease paper into portions/partition size depends on evidence size
Place evidence in a central location on paper
Evidence

20. 7. Scene Evidence Collection Con’t
Fold paper left and right sides in
Fold in top and bottom
Insert the top flap into the bottom flap
Tape-close
Place bindle inside a plastic or paper bag
Fold bag closed
Place a seal over the folded edge of evidence bag
Have collector write his/her name across folded edge

21. 7. Scene Evidence Collection Con’t
Wet evidence should never be packaged in plastic container.
WHY?
DNA will degenerate
Evidence may become moldy, thus useless
Control samples must also be obtained from victim for exclusion. Used for comparison.

22. Chain of Custody Essential in securing the evidence:
Individual who collects evidence marks for i.d. & bags it.
Evidence is properly labeled and sealed.
Collector’s signature is written across sealed edge.
Container is given to next person responsible for its care.
That person takes it to the lab and signs it over to the technician.
Technician opens package for examination.
After examination, technician repackages evidence within its original packaging.
Technician reseals evidence in a new packaging.
Technician seals, signs name across label seal.
Technician signs the chain of custody log attached to the packaging.

23. Chain of Custody proves who and when evidence was collected, handled, tested, etc.
If the chain of custody is broken, evidence can be dismissed in court.
If you have broken the chain of custody & failed to document evidence you can be fired.

24. Others involved in CS Investigations/Protocol:
Entomologists—examine insect behavior/evidence at crime scenes
Anthropologists—analyze skeletal remains at crime scenes
Toxicologist—analyze blood alcohol levels, drug and or poisons
Arson—analyze fire evidence to determine cause
Medical Examiner—medical doctor that determines cause of death