Scenes encountered by post-fire investigators range in their size and complexity and a ‘one size fits all’ approach will not be sufficient.
This requires a means for fire and rescue services to plan for, and respond to, a wide range of investigation scenes.
Levels of fire investigation
There are three levels of investigation:
- Level one: basic fire investigations
- Level two: intermediate fire and explosion (non-terrorist) investigations
- Level three: advanced fire and explosion (including terrorist) investigations
Level one: basic fire investigations
This category refers to what is considered typical fire investigation, generally carried out for completing the Incident Recording System (IRS). In the absence of any earlier indicators, it is also a chance to assess the fire for suspicious or unusual features that may be of interest to other agencies, or offer chances for future learning. This will usually be completed by the attending incident commander and not require the use of specialist fire investigation knowledge or equipment.
Level two: intermediate fire and explosion (non-terrorist) investigations
In general terms, this is an investigation that requires a greater degree of knowledge or control than level one, but that can be managed by use of internal resources. Typically, these investigations will be carried out by a specialist fire investigation team comprising experienced fire officers from the local fire and rescue service.
Level three: advanced fire and explosion (including terrorist) investigations.
In broad terms, due to its complexity or seriousness, this investigation requires the involvement of additional resources, either of a specialist nature (forensic scientist or product specialist) or of a neutral party to oversee or carry out the investigation (for example where there may be a claim or criticism of the host service). At level three, there will almost always be a multi-agency investigation, which will usually involve specialist fire investigation team members.
Most fire and rescue services have two types of investigators; operational crews and a specialist fire investigation team (either full-time or as a bolt-on role for officers in the flexible duty system). The latter work on both level two and level three scenes and will act in accordance with their organisational remit and personal competence.
Other considerations
As well as identifying the level, there will be other areas to consider in how to approach an investigation, including the interest, powers and role of other agencies.
When undertaking fire investigation, it is the responsibility of the fire investigator to ensure that the investigative process follows a logical framework and that all fire investigations are approached without presumption of the origin, cause or responsibility for the incident until the scientific method has yielded a provable hypothesis.
This is achieved by following a series of logical steps:
- Step one: recognises that a problem exists in the case of fire investigation where a fire or explosion has occurred
- Step two: defines the problem, which involves identifying the cause of the fire or explosion
- Step three: the scene is examined and facts are collected; this will require collecting data and gathering information from witnesses
- Step four: the data is analysed; this analysis is based on the knowledge, training and experience of the investigator and if the investigating officer lacks the necessary skills or training they must seek assistance
- Step five: the investigator produces a hypothesis or hypotheses based on an analysis of the data
- Step six: the investigator tests the hypothesis to ensure it can withstand examination, possibly in a court of law
- Step seven: the investigator selects a final hypothesis