Crime Scene Investigation and Documentation - Term 1

What is a Crime Scene

Any location/person/object that may contain information that may relate to the crime.

Including the area the crime was planned

Classification of Crime

Geographical Location

Size of Crime

Primary

Secondary

Geographical Locations

Indoor : house, buildings etc…

Pros : more easily controlled; evidence better protected from weather conditions

Cons : numerous surfaces; complex entry and exit points; high potential for pre-existing material form all occupants (relevant or not)

Outdoor : streets, beaches, fields, public spaces etc..

Cons : weather conditions (rain, wind, heat & sunlight); animals and insects; traffic (roads can’t be closed for an indefinite amount of time to conserve a scene or evidence); large search areas.

Mobile : cars, public transport, boats, people etc…

Cons : combination of indoor and outdoor; potential loss of evidence compared to original location.

People as Crime Scenes

Victims or Suspects may have: injuries, blood, fibres, hair, gunshot residue.

All of which can serve as evidence or help reconstruct a crime scene.

Roles at a Crime Scene

First Responder : addresses immediate threats

CSI Leader/Manager : coordinates the forensic examination as well as sometimes controlling and documenting access to the crime scene

CSI : documents, searches, identifies and packages evidence

Detective : leads the criminal investigation

Photographer : creates an accurate visual record of the scene/evidence

Forensic Scientist : provides specialist expertise

Medical Personnel :

Legal Awareness

Crime scene examination must operate within the applicable law

Legal Consideration

• Lawful authority to enter

• Search powers

• Warrants where required

• Seizure of Property

• Privacy

• Rules of Evidence (Chain of Custody)

• Disclosure (who can have access to info about the investigation)

Locard's Exchange Principle

A fundamental forensic science rule stating that whenever two objects or persons come into physical contact, an exchange of trace materials occurs, meaning that every contact leaves a trace.

Contamination

The introduction of material not originally part of evidence or crime scene

Sources of Contamination

• Investigators

• Emergency Personnel (First Responders)

• Clothing

• Equipment

• Packaging

How to Prevent Cross-Contamination

• Wearing proper PPE

• Double-gloving (different colours)

• Use clean equipment

• Clean/replace tools between items

• Minimise movement of objects

• Controlling entry and exit in a crime scene

• Packaging items appropriately (separately/appropriate bag type)

• Maintain accurate records

Ethical Responsabilities of CSI

Must Remain:

• Objective

• Transparent

• Impartial

• Professional

• Accurate

Must Avoid :

• Selective documentation (DO NOT ignore contradictory evidence)

• Overstating conclusions

• Concealing errors

• Allowing assumptions to influence evidence recovery

“Evidence should inform the investigation, not be forced to support a preferred theory.”

CSI Process Overview

PREPARATION : Receive Notification → First Response → Secure the scene

ON THE SCENE : Initial Assessment → Document the scene → Search the scene → Identify & Recover Evidence → Package & Record Evidence

POST-EXAMINATION : Final Review → Release the scene

Receive Notification

Information should include :

• nature of the incident

• your appointment question (why are they calling?)

• location of the scene

• is the scene currently secure?

• number of victims or persons involved

• known hazards

• whether suspects are present

• whether emergency services are present

Adequate information allows CSI to prepare appropriate PPE, equipment and any specialists needed

First Responders

Their priorities include:

• protect life

• ensure safety

• address immediate threats

• secure and preserve scene

• record initial observations

Life takes priority over evidence, so if any life-saving actions alter the scene, they should be recognised and documented.

Secure the Scene

• Establish boundaries

• Control entry and exit

Ensures that evidence is protected and the scene remains safe.

Initial Assessment

• Identify potential evidence

• Walk-through survey

• Compose a plan of action

Ensures a sufficient and systematic examination

What to Look for During Initial Assessment

• General scene layout

• Potential evidence

• Fragile/transient evidence

• Possible entry and exit points

• Routes of movement

• Signs of disturbance

Document the Scene

• Notes

• Photographs

• Sketches

• 3-D Imaging

Documentation happens before anything is moved or collected and allows another person to understand the scene without having been there as well for the person who was present on the scene to accurately reconstruct the scene even after a long time.

Notes

• Notification

• Case Reference

• Arrival and Departure

• People present

• Evidence identified

• Initial Observations

• Changes made to the scene (e.g. paramedics moved victim, lights introduced..)

• Evidence Recovered

• Actions taken

This may assist with:

• Reports

• Court testimonies

• Reconstruction of the crime scene

Notes should be:

Accurate - record what is actually happening

Objective - separate observation from interpretation

Contemporaneous - record info at the time or as soon as practical

Clear - another person should understand them

Complete - record relevant details and actions

Legible - the record must remain usable

Photography

Photograph first → Examine → Move/Recover

Photos should be:

• Relevant

• Clear

• Properly focused

• Accurately documented

• Appropriately exposed

• Systematic

• Capable of showing context

*All photographs are Evidence! and are presented in court so nothing can be deleted

How to Take Photos

The camera needs the right amount of light = appropriate exposure

3 camera settings for final exposure:

ISO + Aperture + Shutter Speed

ISO : Sensitivity of camera to available light

→ low ISO (100-200) = cleaner image, lots of light

→ high ISO (800-1600+) = brighter image, less light available

Lower ISO is more practical in scene conditions

Aperture : How big the lens opens; affects how much light gets in

It is expressed as an f-number: f/2.8 → f/4 → f/5.6 → f/8 → f/11 → f/16

→ small f-number = big opening; more light enters

→ large f-number = small opening; less light enters

*if a scene allow for it, photos are best taken during the day so CSI may choose to wait till then.

Shutter Speed : how long the camera sensor is exposed to light

→ fast shutter (less than 1s) = shutter briefly opens; less light enters; less risk of movement blur

→ slow shutter (more than 1s) = shutter remains open longer; more light enters; greater risk of camera shake if hand-held.

The Exposure Meter

An in-camera tool that measures the intensity of light reaching the sensor to determine whether an image is properly exposed.\n\n-

Scale: Typically ranges from −3−3 or −2−2 to +2+2 or +3+3\n- Centered at 00: Indicates a balanced, optimal exposure\n-

• Minus values (<0<0): Indicate underexposure (too dark, loss of shadow detail)\n-

• Plus values (>0>0): Indicate overexposure (too bright, blown-out highlights)\n- Guides the adjustment of aperture, shutter speed, and ISO

Order of Photography

General Scene → Specific Evidence

Overall → Mid-range → Close-up

Overall photos establish the scene and its general layout.

They may show:

• exterior of the location

• approaches to the scene

• entry and exit points

• rooms or major areas

• relationship between areas

Must be taken from multiple view points

Mid-range photos show an evidence item in relation to its surroundings

Close-up photos record the detail of the individual evidence

First taken without a scale,

Then with a scale to provide a size reference.

→ positioned carefully but close to the exhibit

→ must be places without contaminating or damaging the item

→ must be appropriate for the evidence

Must be taken perpendicularly (if a light source is used this must be radial to avoid reflections)

Sketches

Sketches clearly show:

• Dimensions

• Position

• Distance

• Orientation

• Spatial relationships

Should contain:

• Case info

• Date and Location

• Scene Orientation (N,E,S,W)

• Evidence location

• Major fixed positions (which are used for reference points

Search the Scene

Systematic searchign maximises evidence recovery.

Crime Scene Search Strategies

1. Line/Strip Search → useful for large outdoor areas with multiple searchers

2. Grid Search → useful for detailed searches of large open areas

3. Spiral Search → useful in open areas, by 1 searcher, where there aren’t a lot of obstacles

4. Zone/Quadrant Search → useful in buildings, homes vehicles etc…

5. Wheel Search (outside → in / inside → out) → used in scenes where the central point is particularly relevant. E.g. a vehicle or body.

6. Point-to-Point Search → following a sequence between items

Identify and Recover Evidence

• Recognise and evaluate items

• Collect, label and mark items

• Record exact location of each item

Handle items carefully to avoid damage or contamination

Package and Record Evidence

Proper packaging preserves integrity and traceability of evidence

Final Review

• Ensure all areas have been examined

• Confirm all evidence has been located and recovered

• Verify documentation is complete

This reduces risk of missed evidence

Release the Scene

The scene is released when all examination is complete

Health and Safety : Potential Hazards

Biological → blood, bodily fluids, infectious material

Physical → weapons, broken glass, fire, unstable structures

Chemiscal → drugs, unknown powders, toxic substances, fumes

Environmental → traffic, extreme temperatures, confined spaces, poor lighting

Continual Risk Awareness of CSI

• Conducts their own ongoing risk assessment

• Identifies hazards associated with forensic activity

• Uses appropriate PPE and safe working practices

• Reports new/changing hazards

• Stops or modifies work if conditions become unsafe

Managing Risk

Identify Risk → Assess Risk → Control Risk → Review → (Reassess → Act)

Controlling Risk may include :

• safe working zones

• controlled handling procedures

• Appropriate, based on the scene, PPE

• Safety and evidence preservation

PPE - Personal Protective Equipment

Changes based on the crime scene

Most common:

• Hooded coveralls

• Safety goggles

• Repiratory protection

• Disposable gloves (double-gloved)

• Shoe covers

Additional:

• Face shield

• High visibility vest (for scene management and safety)

• Arm covers (for intense or messy scenes)

• Disposable aprons (used in high contamination risk)

How to Put on PPE

1. Face mask (to stop saliva spray while talking)

2. Helmet/Hairnet

3. First pair of gloves

4. Coveralls

5. Shoe covers

6. Second layer of gloves ( no skin must be exposed between gloves and coveralls)

*always considered essential regardless of seriousness of a scene

Establishing Scene Boundaries

Inner Cordon : strictly controlled areas ( entry and exit controlled and documented)

→ Access control - Crime Scene Log:

• Name

• Role

• Time of entry and exit

• Reason for entry

Outer Cordon : keeps the public and unauthourised personnel out