Fire scene examination
The short answer is no. When a fire investigator arrives at a fire scene, they have very little information and so cannot be sure at that stage of the circumstances. It is for this reason that fire scenes should be regarded as crime scenes until proven otherwise. An arson scene that involves fatalities for example calls for an extremely detailed, methodical and thorough scene examination and does tend to focus the mind somewhat! Far better that the investigator approaches a scene with this mindset than not as the investigation can ‘relax’ slightly in the event that the fire turns out to be an accident and there is no loss of life. Conversely, undertaking a fire scene investigation assuming it to be an accident can allow complacency to set in.
Having not approached the scene as careful as one might have and allowing evidence to become damaged cannot be undone. At such deliberately set fire scenes points of entry become extremely important as this is often the place that intruders leave behind trace evidence as they force their entry.
Accidental vs deliberate
Both at accidental and deliberate fire scenes the investigator is still looking for an ignition source although the mechanism by which the fire started is often very different. Arsonists will often use ignitable liquids to accelerate the fires they start and residue from such liquids can frequently be found. Fire investigation canines are now commonplace and their ability to locate even the tiniest amount of accelerant is extremely impressive. It is important for investigators, when dealing with fires involving ignitable liquids, to be aware of cross-contamination and strict evidence recovery procedures must be followed.
Deliberately set fires cost the UK economy over £8 billion a year and the reasons for people committing arson are plentiful. Insurance fraud, vandalism, to cover up another crime and revenge are just a few of the many drivers that push people to commit arson.