City of Oswego Fire Department
Arson Awareness
Fire Scene Preservation
City of Oswego Fire Department
Objectives
Identify and describe the importance of observations made prior to, during or after a fire
Describe the importance of preserving a fire scene for cause determination.
Describe methods of preserving fire scene evidence.
City of Oswego Fire Department
Fire Behavior
Fire behavior is predictable. A normal fire follows a predictable path of
fire progression. Growth Stage Free Burning Decay
City of Oswego Fire Department
Fire Behavior
Normal Fire Patterns One ignition source Growth is upward and outward ‘V’ patterns form
City of Oswego Fire Department
Fire Behavior
Abnormal fire growth or burn patterns may indicate non-accidental cause: Unusually heavy destruction in area of origin. Inverted ‘V’ patterns Multiple areas of origin.
City of Oswego Fire Department
Observation Skills
Cause determination is based on various types of evidence. Burn patterns Point of origin Elimination of causes Witness interviews
– Occupants– Bystanders– Firefighters
City of Oswego Fire Department
Observation Skills
Firefighters are primary witnesses to the event, before, during and after the incident
Their observations can assist the efforts of investigators immensely.
Firefighters should be prepared to provide written witness statements after the fire.
Their ability to preserve evidence for investigators is crucial to cause determination.
City of Oswego Fire Department
Environmental Observations
Wind direction and speed Weather conditions Neighborhood conditions
Real estate values For sale signs Problem areas
City of Oswego Fire Department
Observations Enroute
Note fire conditions reported from dispatch. Vehicles or people leaving the scene
Normally people move toward the fire Unusual circumstances or obstacles
Blocked access
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Observations at the Scene
Note time and fire conditions on arrival Occupants clothing Occupants behavior
Over curious Indifferent Too helpful
Bystanders (familiar faces?) Location of fire
City of Oswego Fire Department
Observations at the Scene
Smoke color May indicate what is burning. May indicate the stage of the fire
Fire travel Unusual signs or routes of fire extension.
Rate of Combustion
City of Oswego Fire Department
Observations at the Scene
Exterior evidence Tracks Flammable liquid containers Greatest damage may help locate area of origin
Area of origin Follow damage from least burned area to the
area of greatest damage. Is ignition source readily identifiable?
City of Oswego Fire Department
Observations at the Scene
Means of Entry Were doors locked or unlocked? Signs of force entry prior to arrival.
Condition of Windows Open or closed. Shades up or down Broken
– Is the glass inside or out
– Smoke stained or not
City of Oswego Fire Department
Observations at the Scene
Unusual odors Petroleum or solvents May prompt the taking of samples Any containers on site, inside or out?
Difficulty of extinguishment Did fire react normally when water was applied Did fire reignite or flash back
City of Oswego Fire Department
Observations at the Scene
Room Arrangement Furnishings in place or absent Correct items in the room Do items appear to be substitutes? Signs of burglary Are valuables missing
What’s burning? Can object be identified. If not, eliminate other causes
City of Oswego Fire Department
Observations on Arrival
Signs of fire spread by unusual methods: Trailers Out of place fuel sources. Splash or pour patterns Inverted ‘V’ or cone patterns
Did fire protection work? Detection systems Suppression systems Did system control fire? If not, why not?
City of Oswego Fire Department
Observations at the Scene
Incendiary devices: Trailers Fusees Match books Hypergolic chemical mixtures
City of Oswego Fire Department
City of Oswego Fire Department
Observations on Arrival
Depth of charring Depends on type of wood and length of burn May help indicate area of orign May help determine length of time fire burned
Spalling Annealing of springs Beading on wiring
City of Oswego Fire Department
Observations on Arrival
Burn Patterns: ‘V’ Inverted ‘V’ Truncated cone Hour glass Lines of demarcation Clean burn Staining of glass
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‘V’ Patttern
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Origin and Cause often found at apex of ‘V’
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Area of Origin
City of Oswego Fire Department
Point of Origin/
Source of Ignition
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Line of Demarcation
City of Oswego Fire Department
Clean Burn
City of Oswego Fire Department
Observations on Arrival
Separate fires May be caused by dropdown May be evidence of set
Means of Entry Doors locked or unlocked Signs of forced entry prior to arrival
City of Oswego Fire Department
City of Oswego Fire Department
City of Oswego Fire Department
Observations on Arrival
Indicators of the direction of fire spread There may be more than one ‘V’ pattern
– Look for lowest burn
Melted glass and light bulbs. Different degrees of charring on furnishings
City of Oswego Fire Department
Preserving Evidence
The entire fire scene is of evidentiary value, not just the apparent area of origin.
Overhaul is a destructive, but necessary phase of fire suppression. Opening voids to check for extension. Pulling appliances away from walls Opening furniture cushions, bedding and
mattress to eliminate deep seated fire. All of these activities may destroy evidence.
City of Oswego Fire Department
Preserving Evidence
When conducting overhaul, be able to recognize evidence which may be of use to investigators.
Delay overhaul, if possible, until a fire investigator can assess the scene.
If overhaul cannot be delayed, attempt to keep damage to a minimum, and report observations to investigator ASAP.
City of Oswego Fire Department
Preserving Evidence
Attempt to preserve fire patterns and other physical evidence during overhaul. Inspection holes Leave furniture in place or return to original
position. Minimize water damage. Limit number of personnel in area.
City of Oswego Fire Department
Preserving Evidence
NEVER move or dismantle evidence. Destruction of context Spoliation