Forensic Fire Analysis

Arson is rarely simple, since it is often a complex mixture of physical examination, theory and opportunity, and is typically couched in terms of “what-if”. In our experience it is vital that the scientific elements of an arson case are fully understood to ensure that a reasoned argument can be presented to the courts.

Bericon can help guide you through the smoke by:

• • Where appropriate, undertaking scene examination
  • Examination, or re-examination, of physical evidence from the scene
  • Review of fire reports including critical assessment of the robustness of any conclusions drawn
  • Provision of general information concerning fires: including the behaviour of materials in fire, their ease of ignition and contribution to spread and smoke generation etc.
  • Indicating the likely coursex of a fire had it mot been extinguished
  • Provision of comprehensive and comprehendible reports based on an objective expert review of the evidence and can be produced in a form suitable for submission to the court, or form the basis of further investigation.Alongside our traditional services of fire scene investigation is the capability to assess the analytical data originating from samples taken from a scene (debris) or items of clothing or footwear from a defendant. Typically these are samples analysed at the laboratory using Gas Chromatography Mass Spectrometry to look for the presence of, for example, petrol and white spirit.Whilst the detection of such volatile substances can be of relevance it must be remembered that environmental contamination may be the reason for their presence and this can play a key role in the presentation of our reports.More specialised testing is also incorporated into out fire and arson portfolio. Certain Police Forces utilise a type of testing which analyses the pyrolysis or combustion products which most probably originate from smoke (Smoke Odour Analysis). This is particularly useful when trying to compare the smoke profile from the clothing of a suspect and the profile from debris or items at a fire scene.

Additionally, in certain cases of arson involving petrol it is possible to compare the chemical additive packages in the petrol residues recovered from the scene with petrol recovered from, say, a defendant’s home.

It is unusual to be called to an actual fire scene by a defence solicitor because, by the nature of things, they do not become involved in the detail of the case until well after the debris has been cleared and the affected parties have returned to their normal routine. Thus most of Bericon’s work consists of reviewing what the prosecution’s expert, be it a fire officer, a SOCO or a laboratory based examiner, has said. There is usually little contention about the accuracy of the recording of the scene, or any chemical analysis for accelerants. Where disagreement may arise is in the interpretation of the evidence, either in absolute terms or in the strength of opinion.

One of the guiding principles of fire investigation is that two seats of fire in one property indicates arson. Thus, when one of Bericon’s clients instructed us to review the evidence in a suspect arson case and added that the fire report had indicated two separate fire scenes in adjoining rooms, it seemed likely that our report would merely confirm the prosecution’s case.

Thus in this case, the fire investigator had visited and recorded the scene and concluded that two fires had been set, in adjacent rooms, this view being reinforced by an unburnt region between the two seats of fire. This naturally led to the defendant, who admitted being alone in the house, being charged with arson.

When we at Bericon reviewed the evidence we accepted that the report proffered by the prosecution would explain all the observed facts. However, using our knowledge of fire spread and material behaviour, we were able to offer an equally scientifically robust explanation. This was based on a single fire in one room reaching sufficient severity to cause the tempered glass in the interconnecting door between the rooms to fail, with the radiant heat then available from this fire being sufficient to ignite the furniture in the next room. This fitted all the facts, including the apparent “unburnt” area between the two fires.

When offered as an alternative scenario, it was accepted as a viable reason for the two outbreaks of fire. With two possible reasons to explain the observed facts, the prosecution was not proceeded with.