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
City of Oswego Fire Department
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
City of Oswego Fire Department
‘V’ Patttern
City of Oswego Fire Department
Origin and Cause often
found at apex of ‘V’
City of Oswego Fire Department
Area of Origin
City of Oswego Fire Department
Point of Origin/
Source of Ignition
City of Oswego Fire Department
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
City of Oswego Fire Department