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

1.Securing the Scene 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

1.Securing the Scene First officer on scene responsibilities (check list handout): 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 CSU 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 by keeping a security log Provide brief update to the next-of-command officer to arrive on scene

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) 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?

3.Scanning the 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)

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 body(/ies)

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 2 immovable landmarks 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

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

6.Searching for Evidence Searching for evidence should be systematic Types of searches: Spiral Grid Linear Quadrant or zone

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

7.Scene Evidence Collection 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

7.Scene Evidence Collection 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

7.Scene Evidence Collection 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

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

7.Scene Evidence Collection 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

7.Scene Evidence Collection 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

Chain of Custody 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