The 7 S’s of Crime Scene
Investigation
1. Securing the Scene
2. Separating the Witnesses
3. Scanning the Scene
4. Seeing the Scene
5. Sketching the Scene
6. Searching for Evidence
7. Scene Evidence Collection
First responding officer – it is his/her duty tosecure the scene by limiting access to the scene andpreserve scene with minimal contamination
1st priority – secure safety of all individuals in the sceneby limiting access to it
2nd priority –preservation of evidenceLocard’s exchange principle –contact between individuals andlocations leads to an exchange of trace evidence
First officer on scene responsibilities
(check list handout): 1. Secure safety of individuals at the scene
2. Approach scene cautiously (look, listen, smell)
3. Obtain medical attention for anyone injured
4. Call in backup help, including medical and CSU personnel
5. Separate witnesses
6. Perform initial walk-through (scan the scene)
7. Search scene briefly to notify lab of equipment needed
8. Collect information, including address/location of the scene, time date,
type of call, names and addresses of all parties involved and present
9. Securing integrity of the scene by establishing boundaries of the scene
and setting tape around parameter
10. Protect crime scene by remaining alert and attentive
11. Document the entry and exit of all authorized by keeping a security log
12. Provide brief update to the next-of-command officer to arrive on scene
3rd priority – witnesses must not be allowedto talk to each other to avoid collusion (creation of story by witnesses talking to each other)
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?
Scan the scene to
a. determine where to take photos
b. determine primary crime scene
c. determine secondary crime scene
( if this applies to the case)
Examiner needs:
1. Photos of overall area
2. Close-up photos with and without
measuring ruler
3. Photos of triangulation of stationary objects
4. Photos taken from different angles and
distances
5. Several close-up photos of any evidence
and body(/ies)
A rough sketch of the scene is made noting –
position of body (if any) any other evidence
Sketch should include:
1. Objects measured from 2 immovable landmarks
2. North should be labeled
3. Scale of distance should be provided
4. Objects in the vicinity of the scene should be
included
Indoors: doors, windows, furniture, etc
Outdoors: trees, vehicles, hedges, etc
5. Name of Investigator drawing the sketch.
Final Sketch – done latermore accurate copyused in court proceedingcomputer programs can be used
Should include: NorthScaleCase #DateLocationName of officer/investigator
Searching for evidence should be systematic
Types of searches:
1. Spiral
2. Grid
3. Linear
4. Quadrant or zone
The type of search depends on:
1. Area of the crime scene
2. number of investigators present
The location of evidence should be:
1. Marked
2. Photographed
3. Sketched
Evidence needs to be – properly packaged sealedlabeled
Liquids and arson – stored in airtightunbreakable containers
Biological evidence – stored in breathablecontainers for evidence todry out to reduce mold growth
Biological evidence – a. Needs to dry out in
breathable container
b. Is stored in paper
bindle (druggist’s fold)
c. Placed in plastic or
paper container
d. Is later sealed w/tape
e. Collector signs his/her
name across the tape
An evidence log and chain of custody document
must be attached to the evidence container
Evidence log should contain:
1. Case #
2. Item inventory #
3. Description of evidence
4. Name of suspect
5. Name of victim
6. Date and time of recovery
7. Signature of person recovering evidence
8. Signature of any witness present during collection
Packaging Evidence:
1. Choose appropriate-size sheet of clean
paper for bindle
2. Crease paper into portions/partition size
depends on evidence size
3. Place evidence in a central location on paper
Evidence
4. Fold paper left and right sides in
5. Fold in top and bottom
6. Insert the top flap into the bottom flap
7. Tape-close
8. Place bindle inside a plastic or paper bag
9. Fold bag closed
10. Place a seal over the folded edge of
evidence bag
11. Have collector write his/her name across
folded edge
Wet evidence should never be packaged in
plastic container
DNA will degenerate
Evidence may become moldy, thus useless
Control samples must also be obtained from
victim for exclusion
Essential in securing the evidence:
Individual who finds evidence marks it for id and bags it
Final container for evidence is a collection bag which is labeled
and then 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