Preserving a fire scene Flashcards
Guarding and controlling the scene
To ensure origin and cause of the fire are established, the scene must be controlled and protected from the time Fire/Police arrive until the scene examination is completed.
The Fire Service will ensure the scene is secured while the fire is extinguished.
Scene security considerations for Police are:
- ensuring the scene is not interfered with
- exclusion and control of on-lookers, property owners and other interested parties
- preserving evidence
- preventing looting
Attending Police should also:
- be aware of re-ignition from hotspots after the fire is extinguished
- be vigilant and watch for possible suspects
- identify any witnesses among onlookers and passers-by
- report all matters of significance to the O/C investigation and/or scene co-ordinator.
Fire scene contamination
Contamination of the fire scene is always an issue, given the very damaging nature of fire itself, and the damage cause in the effort required to extinguish it.
To assist in preserving the scene as much as possible whilst fire fighting operations are in progress, the investigator should liase with the Fire incident commander to limit unnecessary operations within the area of origin, including the number of personnel inside a structure.
Stop fire crews from removing fire debris from the structure to assist the owner/occupier after the fire is extinguished.
Scene preservation
To assist in scene preservation, consider these points:
Scope
How much of the area needs to be preserved?
- single room
- entire building
- a large area that includes a building or buildings
- outside areas.
Cordon
- identify the centre of the scene
- tape off outside, what is considered to be the most obvious item of evidence that is furthest away from the centre of the scene
- in large scenes the natural boundaries could be used to dictate your zones.
Make cordons as wide as practical.
Common approach path
All traffic through the scene should be limited to ‘corridors’, i.e. the paths which will keep disturbance of the scene to a minimum.
Ideally, the investigator should search the areas to be used as corridors prior to them receiving any other traffic. This will reduce the possibility of ‘evidence’ being introduced to the scene after the event. It will also reduce the possibility of evidence being damaged during subsequent fire inspections and investigation.
Where it is difficult to preserve the scene
In certain circumstances, such as demolition of specific areas due to safety, it may be difficult to preserve the scene. In cases such as this the investigator must record the scene, prior to demolition, by:
- sketches
- photographs
- plans
- video recordings.
This will assist in recalling the layout of the premises prior to demolition work being carried out. Some steps can be taken as shown below in examining the scene without disturbing it or endangering staff.
When dealing with suspicious fatal fires, consideration should be given to ‘storage’ of the removed spoil.
This can be done in the cleared warm area of your scene if practical and should be clearly marked where the spoil has come from in your scene. This provides the investigator with a backstop should you need to revisit your search.
Personnel
A Specialist Fire Investigator should be present at all fire scenes Police are required to attend. You may also need the assistance of one or more of these:
- fire investigation liaison officer
- ESR scientist
- rural fire investigator
- photographer
- fingerprint technician
- explosives inspector
- electrical inspector
- building inspector
- insurance assessor
- accountant
- forensic mapper/original floor plans
- pathologist
- vehicle inspector
- civil aviation inspector
- mines inspector
- forestry expert
- agricultural expert
- marine surveyor
- heating engineer
- meteorologist.
The O/C Investigation should then:
- appoint an exhibits officer
- appoint a crime scene co-ordinator (if required)
- advise the Fire Investigation Liaison Officer
- appoint a scene examiner.
Preparing the examination
Successful fire investigation requires a logical, step by step approach commencing in the undamaged area and progressively working through to the point of origin.
The point of origin is the exact location at which:
- a component failed,
- a fire was maliciously lit, or
- an accidental fire originated.
External examination
The external examination takes into account:
- Adjoining premises which often reveal:
* - accelerant containers
* - attempts at forced entry
* - broken windows
* - forced doors
- Nearby alleyways/streets/driveways
- The yards and outbuildings of the fire effected property
- The periphery of the structure itself
- What distance debris was scattered, particularly if drums or cylinders have exploded.
The surrounding area of the involved premises may also reveal:
- accelerant containers
- contents of outbuildings missing
- property run-down
- business appears to be struggling.
The damaged structure itself may reveal:
- jemmy marks or other signs of forced entry on windows or doors
- window glass broken before the fire was ignited
- burn patterns above doors and windows and “V” shaped burn patterns on external cladding.
Preliminary internal examination
Preliminary internal examination should involve a slow walk through the premises, from the area of least damage to that of most damage, taking note of indicators such as:
- low stock levels in commercial premises
- building areas in need of repair
- signs of hardship (empty flats, shops to let, etc.)
- missing family photographs, furniture and personal items
- lack of clothing in wardrobes and drawers
- rifled premises
- position of clothes if not in wardrobe or drawer
- open filing cabinets or missing files
- forced entry into an empty till
- presence of accelerant containers or trails
- separate unrelated seats of fire
- owner/occupier attitude during walk through (if access is permitted)
- unusual odours
- burn patterns
Detailed internal examination
Following the preliminary examinations, you will accompany the Specialist Fire Investigator while they complete a detailed examination of the scene.
In this examination they will observe, note and take into account a number of observations including:
- smoke deposits and burn patterns
- spalling (the cracking or chipping of concrete as a result of being heated and cooled)
- damage to wall studs
- damage to roofing timbers
- damage to window sills and door edges
- soot deposits on window glass and craze patterns
- floor areas burned through
- skirting board damage
- elimination of false low burns
- removal of fire debris, and
- under floor inspection.
It is at the conclusion of this examination that the Specialist FIre Investigator will be able to determine:
- area of origin
- point of origin
- the seat of the fire.
In determining the seat of the fire the Specialist Fire Investigator will consider:
- witness’ reports
- when they first noticed the fire, and where they were at the time
- the state of the fire at that time
- wind direction and speed, and the weather
- the direction of spread
- the colour of the flames and smoke (this may also point to the cause; for example, black soke may indicate a petroleum product based fire)
- the severity of the damage (because fire and heat usually rise, the area at the lowest level of burning with the most severe damage is often the place where the fire started. Remember that lateral and downward burning can occur with ome materials and in the presence of accelerants or draughts)
- the depth of charring (probing may indicate where the fire has been burning or smouldering the longest)
- the presence of ‘starting devices’
- the reports and opinions of other specialists.
Do not assume that all the evidence has been destroyed. Even if the destruction is total, examine the scene carefully to recover all possible evidence of the cause of the fire.
The cause of the fire
Look for:
evidence of accelerants, such as:
- containers
- traces in debris
- smell
- unusually rapid spread or intensity of fire
- uneven burning
- burning under or behind boards where the liquid has run through the cracks
- multiple seats of fire
evidence of intentional interference, such as:
- tampering with the alarm or sprinkler system
- hindering access
- misdirecting fire fighters
- evidence of intentional removal of valuable property, or substitution of property
- signs that furniture was rearranged to create a fire base
- signs that windows and skylights were opened to create a draught
- foreign material and objects, such as screws/batteries, that might be part of a device
- signs a crime has been committed. THe property may have been burned to destroy the evidence. Even when a building has been burnt to the ground, the state of the recovered locks and fasteners may show whether it was secure at the time of the fire
- signs that a heater, soldering iron or other electrical appliance has been left on
- inconsistencies (for example, that the fire is rapid but there is no obvious cause)
- unusual burn patterns or unusual time factors (for example that the fire started after the building was secured).
Exhibits
1
Photograph in situ, label the exhibits and preseve them in containers.
2
Use approved arson kits if these are available; if not, use any suitable containers such as unused four litre paint tins.
3
Take these control samples:
- charred timber and ashes or debris from the seat of the fire for examination and comparison with samples from other points
- any accelerants found near the scene
- soil from the surrounding area.
