The 7 S’s of Crime SceneInvestigation

First responding officer – it is his/her 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 it 2nd priority –preservation of evidence Locard’s exchange principle – contact between individuals and locations leads to an exchange of trace evidence

First officer on scene responsibilities (check list handout): 1. Secure safety of individuals at the scene2. Approach scene cautiously (look, listen, smell)3. Obtain medical attention for anyone injured4. Call in backup help, including medical and CSU personnel5. Separate witnesses6. Perform initial walk-through (scan the scene)7. Search scene briefly to notify lab of equipment needed8. Collect information, including address/location of the scene, time date, type

of call, names and addresses of all parties involved and present9. Securing integrity of the scene by establishing boundaries of the scene and

setting tape around parameter10. Protect crime scene by remaining alert and attentive11. Document the entry and exit of all authorized by keeping a security log12. Provide brief update to the next-of-command officer to arrive on scene

3rd priority – witnesses must not be allowed to 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 area2. Close-up photos with and without

measuring ruler 3. Photos of triangulation of stationary objects4. 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 evidenceSketch should include:1. Objects measured from 2 immovable landmarks2. North should be labeled3. Scale of distance should be provided4. Objects in the vicinity of the scene should be

included Indoors: doors, windows, furniture, etc Outdoors: trees, vehicles, hedges, etc

Final Sketch – done later more accurate copy used in court proceeding computer programs can be usedShould include: North Scale Case # Date Location Name of officer/investigator

Searching for evidence should be systematic Types of searches:

1. Spiral 2. Grid3. Linear4. Quadrant or zone

The type of search depends on:1. Area of the crime scene2. number of investigators present

The location of evidence should be:1. Marked2. Photographed3. Sketched

Evidence needs to be – properly packaged sealed labeled

Liquids and arson – stored in airtight unbreakable containers Biological evidence – stored in breathable containers for evidence to dry 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 evidence4. Name of suspect5. Name of victim6. Date and time of recovery7. Signature of person recovering evidence8. Signature of any witness present during collection

Packaging Evidence:1. Choose appropriate-size sheet of clean paper

for bindle2. Crease paper into portions/partition size

depends on evidence size3. Place evidence in a central location on paper

Evidence

4. Fold paper left and right sides in5. Fold in top and bottom6. Insert the top flap into the bottom flap7. Tape-close8. Place bindle inside a plastic or paper bag9. Fold bag closed 10. Place a seal over the folded edge of

evidence bag11. 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