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Case study: ASK defends suspected arsonist

The rate of conviction for arson is 9% compared to 20% on average for other crimes. When ASK was involved in the investigation of a case of suspected arson, it became clear that misunderstandings between the police and fire investigators – particularly over the tricky business of collecting evidence after a fire – could be contributing to this low clear up rate.

The case:
Mrs Smith (not her real name) was arrested after the fire brigade was called to attend to a fire at her home. Arson was suspected largely due to there being two main areas of damage in the house – one on the ground floor and one on the first – leading to the assumption that there were two seats to the fire. The fire inspector confirmed this conclusion in his report to the police.

Swabs were taken from Mrs Smith’s hands and her clothes were retained as evidence. During her interview she changed her opinion of the likely source of the fire, further increasing suspicion of arson. Mrs Smith stated she had left a cigarette alight on the sofa armrest in the downstairs room, which somehow ignited it.

ASK involvement:
ASK showed that the fire damage on the first floor window was consistent with eyewitness accounts, according to which the fire migrated from the ground floor to the first floor bedroom. We agreed with the prosecution that the rapidity of fire spread ruled out Mrs Smith’s cigarette hypothesis. However, we pointed out that an electrical spark could have ignited vapour above an open container or spill of flammable liquid – the house was being redecorated and there were paints and rags soaked in paint thinners in the room, as well as a variety of live electrical equipment. We cited statistics showing that tumble dryers are responsible for 3-4% of all house fires, and in a third of these fires the failure modes could not be determined.

Furthermore, ASK identified serious weaknesses in the scientific evidence offered by the prosecution. No samples were taken from the upstairs room, or from Mrs Smith’s shoes. Arsonists often spill accelerants on their shoes and it is thus standard practice to take swabs from them. In addition, the clothes the police had intended to use as evidence could not be analysed because the bags containing them were not properly sealed.

The result:
Mrs Smith was eventually acquitted, after being refused bail and spending five months in prison. What came out of the trial was a strong impression that no one had been in charge of the investigation: for example, when asked why no samples were taken from the suspected seat of the fire upstairs, the police said that they were not instructed to do so by the fire investigator, who in turn, claimed that it was not his role to tell the police how to conduct their investigation.

Given our experience, it appears a lack of communication between the fire service and the police, and a lack of understanding of what is expected from each in terms of evidence collection and analysis, is at least partly to blame. Finally, in our opinion, Mrs Smith might well have been spared her unnecessary ordeal had a forensic scientist been involved at an early stage, as recommended in official guidance.

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