Crime Scenes: Minor vs Major Crimes

Crime Scenes

• A crime scene is any location, person, or object linked to an alleged offense, including digital environments.
• Primary crime scene is the location of the original alleged offense
• Secondary crime scene includes all elements, locations, objects, and traces linked to the alleged offense.
• Crimes are categorized as minor (volume) or major.

Minor (Volume) Crime

• Includes less serious offenses without violence or aggravating circumstances (e.g., weapons)
• Civilian and sworn Scene of Crime Officers (SOCOs) examine minor crime scenes and exhibits.
• Civilian SOCOs use basic techniques to collect, protect, and document the scene
• Examples include theft (from vehicles, dwellings, retail premises, persons) and malicious damage (property, graffiti, car damage).

Major Crime

• Involves serious or violent crimes, and/or aggravating circumstances.
• Examples in NSW include homicide, assault (actual or grievous bodily harm, malicious wounding, sexual assault), and aggravated robbery (armed, with wounding, in company).
• Both sworn and civilian SOCOs attend and examine major crime scenes with increased complexity and advanced techniques.

Other Scenes and Incidents

• Crime scene examiners investigate unnatural, sudden, or suspicious deaths to rule out foul play.
• Includes suicides, unexpected deaths, accidental deaths, deaths by misadventure (accident), and industrial accidents/deaths.
• Other incidents include search warrants, forensic procedures (samples from suspects/victims), post mortems (documentation, fingerprinting), Sexual Assault Identification Kits (SAIK) collection at hospitals, photographing wounds, and critical incidents involving police.

Traces

• Traces are any material linked to the activity under investigation, left at the scene by persons of interest (POI) and/or victims be they physical or digital
• These can help reconstruct events and provide spatial and temporal information.
• Biological traces include bloodstains, semen, saliva, urine, and DNA-containing material.
• Physical traces include marks, impressions, patterns, and microtraces (fibers, paint, glass, gunshot residue).
• Digital traces include CCTV, emails, GPS data, and mobile data.
• Locard’s exchange principle is key: traces are transferred during activity.
• Footwear impressions can indicate entry/exit points, movements, and the number of individuals.
• Broken windows can reveal the number of glass fragments and the direction of breakage.
• Traces can originate from or be carried away by suspects/victims.

Linkage of Traces

• Footwear impressions can link a suspect/victim to a crime scene.
• DNA under a victim's nails can link them to a suspect in an assault.
• Glass fragments on a suspect's clothing can link them to a crime scene.
• Traces can be material deposits or results of actions (molded traces).

Locard’s Principle of Exchange Transfers

• Single transfer: trace found on A originated from B (e.g., shoe mark on floor).
• Double transfer: trace found on A originated from B, and trace found on B originated from A (mutual exchange).
• Stepping on a dusty floor is an example of double transfer.
• Double transfers are more valuable as they solidify evidence.

Aims of Crime Scene Investigation

• Based on Locard’s principle, aims to observe, detect, record, and collect traces to answer key questions.
• Focus is on who, what, where, when, why, and how of the offense.
• Fire scene aims: determine origin, cause of ignition, and development (chronology) of the fire.
• Fire scenes are dangerous and require clearance from firefighters/engineers.
• ABC of investigation: assume nothing, believe nothing, challenge everything.

Steps of Crime Scene Investigation

• Four main stages: secure and protect, document the scene, search the scene, and collect evidence.
• Secure and protect: preserve the scene and traces to reduce contamination, extend cordon if needed.
• Document the scene: create accurate record of the scene, general documentation before entry.
• Search the scene: identify, document and mark items/traces of interest, search for fingermarks.
• Collect: properly collect and package items and traces.
• Move from general to particular: start with non-destructive examination, then more specific/destructive.
• Document as much as possible to reduce potential damage.
• General: observe outside the scene, general photography, sketches, notes on access/exit, description.
• Specific: observe visible evidence, corpses or disturbed objects, mid-range photos of evidence.
• Particular: detailed observation inside the scene, close-up photos, search for fingermarks, footwear impressions, toolmarks, fibers, paint, or glass.

Arrival at the Scene

• Examiners are contacted with basic information (address, contact, overview), but accuracy may vary.
• Bring all standard equipment and make no assumptions upon arrival; verify information.
• Talk to police, investigators, victims, and witnesses to gather information.
• This can help determine who entered the scene and their paths to identify potential contamination

Preservation of the Scene

• Verify police have permission/warrant to enter; evidence is inadmissible without it.
• Assess existing scene preservation; cordons should be larger than the scene.
• Assess hazards (biological, chemical, explosive) and risks before entering.
• Coordinate resources (specialists) and examinations.
• Secure any secondary scenes.
• Confirm police are maintaining a crime scene log to track who enters and why ensuring proper preservation.
• Document any life-saving attempts, position, and state of the body within the scene.
• Conduct a cursory search for identification.
• Collect visible traces off clothes/body (fiber taping) only with pathologist agreement.
• Protect hands with paper bags and arrange collection of clothing/jewelry at the morgue.

Safety and Hazards

• Psychological hazards: violence-induced strain.
• Biological hazards: bodily fluids and deceased remains.
• Environmental hazards: extreme temperatures and wildlife.
• Physical hazards: sharps and cramped spaces.
• Chemical hazards: chemicals examiners use and those at the scene.

Inner and Outer Cordons

• Outer cordon: protects the scene from the public and media.
• Only police/authorized persons can enter; police maintain an entry log.
• Inner cordon: where examiners conduct examinations; entry is limited to authorized personnel.
• Point of Entry (POE): the location where the offender entered the scene.
• Protecting POEs from contamination is crucial; determine entry/exit points before entering.
• Examiners should use a different entry point.
• Signs of POE: broken glass, damage to doors/windows/locks.

General Examination Sequence

• Visual examination: assess the area and note items/areas of interest.
• Crime scene perimeter: ensure all relevant areas are included, adjust if needed.
• Risk assessment: identify potential hazards.
• Enter crime scene: use a different entry point from offenders (if possible).
• Walk-through: clear floor and note points of interest, begin initial notetaking/photography.
• Examination plan: prioritize areas for examination (e.g., evidence exposed to the elements).
• Discuss the plan with officer in charge/crime scene manager for specific focus points (e.g., weapons).
• Thorough light source search: use multiple wavelengths, and note findings.
• Note any areas, traces, or points of interest found during the light search and capture scene record photography and notes
• Recover traces and exhibits: prioritize collection based on fragility.
• Develop/capture fingermarks: use physical methods first, chemical methods last, and photograph all.

Light Source Searches

• Move from non-destructive to destructive testing; start with light sources.
• Grazing light search: white light at a 45-degree angle.
• It highlights small items, glass, fibers, hair, and shoemarks in dust.
• Useful on floors.
• Alternate light sources: bodily fluids glow under UV light; blood absorbs blue/green light.
• 400-700 nm (white): general searching, footwear marks, blood marks, fingermarks, stains.
• 350-380 nm (UV): blood marks, semen, gunshot residue fibres, bruising, bite marks, drug residue, paint traces.
• 420-470 nm (blue): blood marks, biological fluids, accelerants, bone, teeth.
• 480-560 nm (green): fibres, accelerants, bone, teeth.
• Mark traces in general search and come back later

Documenting the Scene

• Notetaking: make contemporaneous notes.
• Should include communications or analyses conducted.
• Notes are legal documents.
• Must: be in ink, chronological, include observations/tests/results, legible, with mistakes crossed out, initialed, and dated.
• Sketching: supplements photography.
• Captures relative positions, layout, and key areas.
• Provides a simplified view and can be used for CAD plans in court.
• Types: plan view (overhead), elevation views (vertical planes), and sketches of exhibits/traces.
• Imaging/Photography: record video, capture still images, 360-degree imaging (digital reconstructions).
• Use digital SLR cameras for still images, working from outer cordon inwards.
• General images: overall layout, floor to ceiling including all of the walls, taken from outside the scene.
• Mid-range images: exhibit placement within context, relevant position.
• Close-up images: details of exhibit or trace using a macro lens.
• Imaging of the crime scene purpose: refresh memories, relationships of items, allow measurements, convey the scene to those not present.

Chain of Custody

• Legal document tracking movement of an exhibit from the crime scene to analysis.
• Maintains exhibit integrity and prevents tampering.
• Each handler and test conducted are recorded.

Collecting Traces

• Hand-picking: used for larger exhibits (glassware, clothing).
• Plucking: removing fibers with tweezers.
• Swabbing: used for biological fluids (blood, semen, saliva), trace DNA.
• Lifting: using gel lifts for dusted fingermarks (when photography is insufficient) or tape lifts for fibers.
• Photographing: capturing traces like fingermarks and shoemarks.
• Sifting: for small bone pieces/traces in clandestine graves.

Packaging Traces

• Use paper bags/envelopes/folds placed in secure paper packages.
• Paper allows items to breathe and reduces potential static electricity.
• Specialized packaging is available for drugs, cash, and weapons.
• Package safely; use cardboard tubes for sharps, a hard shell case for firearms/ammunition.
• Notify a police officer if handling a firearm without training.
• Display safety warnings on packaging for sharps, glass, weapons, and presumed biological contamination.