Fires 9 - Investigation and Analysis Flashcards
What does a burn pattern look like if a liquid fuel is used?
sloshing
What does a burn pattern look like it petrol is used?
On carpet?
splats and maintains the shape when burning
non-uniform and super localised
What three things does firefighting involve?
- high pressure hoses
- windows smashed for ventilation
- items cleared out
What three things are used to reconstruct scene?
- speak to witnesses
- look a pre-fire photos or if it is available camera footage/cloud photos (made easier nowadays with digital records, cloud storage/social media. this can help return objects to original locations or tell you if something was out of place when burnt (give potential motive if burned something they moved intentionally))
- match up objects to burn patterns
What must movements be in reconstruction?
justified and fully recorded
What can be said about smoke record left at fire scene?
- smoke will have left deposits on all open surfaces (anything without smoke deposits must have been covered)
- it is a great indicator for depicting what happened at scene
- door frames show position of door
- glass show whether broken before or after fire
- objects on desks and walls will leave a shadow
- physical barrier to the smoke makes scene reconstruction easier
Why might excavation be needed?
debris (burnt objects, walls, ceilings, coverings…) may have fallen around the scene and could cover the seat of the fire so excavation may be needed:
- to find bottom of V-patterns
- to establish order which objects fell
- to find remnants of ignition sources
What can be said about fire and electrical faults?
How can you identify the differences?
electrical faults can cause fires but fire can also cause electrical faults
e.g. can expose wires and cause short circuits as the fire spreads and damages plugs
- excess current results in heating of cable
- this melts insulation which means wires come into contact
- arcing wires develop beads
- beads - imply wires been arcing for while and this is cause of fire
How can electrical fires start (3 ways)
1 - counterfeit electronic goods
2 - design faults
3 - incorrect use
What four questions should be asked surrounding electrical fires?
was it plugged in and turned on?
- if no electricity running through appliance = didn’t start fire
- smoke record and position of switches will tell you if an appliance was on when the fire started
was it at the point of origin?
- is it near the origin?
was the fault there before the fire? and were there fuels nearby?
- need to find fault and find nearby fuel that was ignited by fault
- if these are not there then the item probably didn’t start the fire
What can be said about people who have had previous accidents with fire?
What questions must be asked about lifestyle of these individuals?
when people have an accident with fire, it is not usually the first time they have acted that way
- are there carelessly discarded cigarettes around or cigarette burns in other areas?
- any evidence of prior minor burning from cooking?
- chip pan on stove?
- unsafe electricals around?
- candle use? metal disks from tea light candles?
What can be said about materials that are used to spread a fire?
paper, furnishings and fluids may leave characteristic burn patterns and leave multiple seats of a fire
What must be noted if visualise tell-tale signs of accelerant use at fire?
synthetic furnishings may melt to produce similar patterns and this can be misleading hence why sampling is important so can analyse samples
What can be said about the ignition source of an arson fire?
- if a match - usually no evidence left of it as burnt but sometimes some phosphorous left behind
- unlikely to leave lighters/box of match behind
- suspicious burn patterns or residues are more reliable than trying to find these ignition sources
How can make timing devices?
- a candle burning until it reaches fuel source
- ignition of a timer switch with soldered connections - can specify time as short will occur when timer hits zero
What are nine suspicious physical signs of arson?
- several seats of fire, or in unusual place e.g. in middle of room not near a power outlet
- accidental causes eliminated or highly unlikely - when no accidental cause = start thinking about arson
- previous fires in building or area (indicative of criminal activity)
- repeat involvement of individual
- unnatural spread of fire, spread trailers – evidence of accelerants
- seat near expensive equipment = insurance fraud
- improbable time for accident (cooking fires in the evening, electrical fires less likely at night)
- alarms etc. deactivated
- incendiary devices
What are seven suspicious circumstantial signs of arson?
- records destroyed
- financial difficulties
- contents removed prior to fire
- insurance claim not filed once questions asked (someone who gets cold feet after police enquire about possible fraud)
- audit/stock taking just about to happen
- forced entry, evidence of search
- interested parties know a lot, pay close attention
