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