Unconfirmed accelerants
| Published date | 01 January 2018 |
| Date | 01 January 2018 |
| DOI | 10.1177/1365712717746419 |
| Subject Matter | Articles |
Article
Unconfirmed accelerants:
Controversial evidence in
fire investigations
Marika Linne
´a Henneberg
University of Portsmouth, UK
Neil Richard Morling
London Fire Brigade, UK
Abstract
Fire investigation is arguably one of the most difficult areas of investigation. The fire scene and
available evidence has often been burnt, melted, smoke-stained, water-damaged and trampled
on, but the fire investigator still has to make important distinctions between whether a fire was
accidental or deliberate (arson). Modern fire investigations often rely on portable electronic
detectors to identify ignitable liquid residue (ILR), or accelerant detection canines (ADCs),
trained on a number of target substances. An analysis of cases from England and Wales, the
United States of America (USA) and Canada demonstrates that sophisticated admissibility
frameworks have not been effective in rejecting opinion testimony given by investigators and
dog handlers that unconfirmed dog alerts where laboratory tests were negative provided proof
of arson. This is problematic and controversial, and the authors conclude that such testimony is
not compatible with modern forensic or scientific standards and should not be admitted into
courts.
Keywords
accelerant detection canine, admissibility, arson investigation, expert evidence, fire
investigation, opinion, search dogs, unconfirmed accelerant
Introduction
If someone said that dogs have provided ‘irrefutable’ evidence in criminal courts, this would most likely
be met with skepticism, laughter or disdain. However, this is what has happened in several jurisdictions,
largely enabled by admissibility frameworks that treat such evidence as capable of belief. The dog does
not appear in court to woof its testimony. Instead its evidence is heard through a proxy or an
Corresponding author:
Marika Linne
´a Henneberg, University of Portsmouth, 141 High Street, Portsmouth PO1 2HY, UK.
E-mail: marika.henneberg@port.ac.uk
The International Journalof
Evidence & Proof
2018, Vol. 22(1) 45–67
ªThe Author(s) 2017
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DOI: 10.1177/1365712717746419
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intermediary, namely the dog handler. That dogs have an olfactory system that far exceeds that of
humans is accepted and not refuted. However, that ‘dog testimony’ has been the known source of
wrongful convictions also need s to be acknowledged. For example , William Dillon was convicted
of murder in Florida, USA, in 1981 and spent nearly 27 years in prison based on testimony from a dog
handler, questionable eyewitness identification and a jailhouse informant. The dog handler testified that
his dog had linked Dillon to the crime scene and a T-shirt worn by the perpetrator (The National Registry
of Exonerations, 2012a). DNA testing of the T-shirt, which had the victim’s blood on it, excluded Dillon
and he was exonerated in 2008 (Innocence Project, no date). This is only one example of a dog handler
exaggerating or misunderstanding the capability of their dog in a criminal investigation and subsequent
court case. Many more cases exist from a variety of fields including fire and arson investigations.
The first half of this article focuses on fire and arson investigations, the detection of accelerants and a
number of critical issues that are associated with this process. Fire investigations should be scientifically
and forensically sound and produce evidence that can be presented in court. The use of accelerant
detection canines (ADCs), dogs trained to indicate the presence of an accelerant, is common in fire
investigations. Once such a dog has alerted, samples must be taken and the presence of a potential
accelerant needs to be confirmed in a laboratory, through scientific testing. Nevertheless, in a number of
cases from England and Wales, the United States of America (USA) and Canada, evidence from
unconfirmed dog alerts have been admitted into courts, with fire investigators or dog handlers giving
opinion expert evidence, even when subsequent laboratory tests were either never conducted or where
these test were negative. Problems associated with tunnel vision and case construction are known to
occur in criminal investigations where, instead of an unbiased fact-finding mission, all focus is on one
particular suspect and only evidence that supports the guilt of that suspect is used in the narrative of the
favoured hypothesis of what happened (see e.g. Findley and Scott, 2006; Henneberg and Loveday,
2015). Fire investigations can be seen as particularly vulnerable to some of these problems as they are
the starting point for any criminal investigation, and the fire investigator has to make the important
decision of whether a fire was accidental or deliberate (arson). Furthermore, these decisions will influ-
ence any subsequent court proceedings.
The second half of this article focuses on the admissibility frameworks of England and Wales, USA
and Canada. These three jurisdictions are all shaped by the English common law and share broad
similarities in how the admission of expert opinion evidence is regulated, which make them suitable
for comparison. Cases where unconfirmed ADC alerts have been used in court are analysed, and a
number of key points to consider when dealing with such evidence are identified. There are concerns
over the way in which unconfirmed dog alerts are admitted into courts with little or no scrutiny. The
probative value of an unconfirmed dog alert is minimal, but the prejudicial effect can be immense.
The article concludes that under no circumstances should dog alerts that have not been confirmed
through laboratory testing of samples from the fire scene be allowed to be presented in court as proof of
arson, through opinion expert evidence given by fire investigators or dog handlers. It is argued that such
evidence is not compatible with mode rn scientific and forensic methods , standards and principles.
Unconfirmed dog alerts must be seen as problematic and controversial as these can be the source of
grave miscarriages of justice, including wrongful convictions.
Fire investigations and the scientific method
It is vital that all forensic science expert testimony is methodically robust (Carr et al., 2016). Fire
investigation is a specialised discipline of forensic science (Stauffer et al., 2008: 5) that can often be
seen as a world unto itself. It is a complex and demanding endeavour that takes place in a hazardous
environment, exposing investigators to scientific and professional challenges not found in other fields of
forensic science (Lentini, 2006: xvii). Fire investigation is often known as ‘origin and cause’ investi-
gation based on the need for every investigation to answer the two core questions of where and how the
fire started. To be able to do this, a fire investigator must have a thorough understanding of many
46 The International Journal of Evidence & Proof 22(1)
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