Examination of Firearms Review: 2007 to 2010 - Interpol

2. Fire scene examination
2.1 Site examination techniques and arson dogs
A fairly modest amount of work has been done for improvements in fire field
investigation during the last three years. A practical guide emphasizing the
significance of a good and thorough fire scene investigation has been published for
first responders. A proposal for doing site examination in a specific order, including
the correct documentation consisting of photography and sketches with dates and all
important information, is essential for securing quality of the work. Being aware of
one’s own behaviour at a fire scene is crucial in order to avoid damaging or altering
the scene. Preserving evidence is very important for final fire investigation in order to
determine the origin and spreading of the fire throughout the scene. 2, 3 A thorough
compilation of fire patterns includes an overview of both historical and recent
research. It emphasizes the need for burn pattern analysis in respect to pattern
reproducibility and formation airflow including ventilation studies. 4
The selection of fire debris samples can be challenging due to destructive processes
occuring during a fire. A study about a liquid fuel on carpet was conducted in order to
aid the selection process. The aim was to reveal the physical processes of and
indicators left by such a fire. The article largely questions the current practices
involved in fire site examination and proposes scientists to undertake research work
to advance the role of science in fire investigation. 5 A book about fire debris analyses
includes a chapter focusing on detection of ignitable liquid residues at fire scenes
with colour pictures of burn patterns where ignitable liquids have been used and
comparison pictures where they have not been used. Principles of electronic sniffers
and colorimetric tubes are also demonstrated including both the benefits and
disadvantages of the methods in question. The operating principle of ignitable liquid
absorbent and ultraviolet detection as well as the use of these methods is also
considered. 6
Portable field devices — misleadingly also referred to as electronic noses — have
been studied in a few articles. Fluorescence-based vapour sensors have been
designed and tested. The results of analyzing petroleum distillates in different
experiments seem promising, although more studies are needed to prove the
usefulness of the devices. 7 An artificial nose using optical fibre arrays to sense
vapours has also been developed. Fibres are functionalised with analyte sensitive
materials, which are also cross-reactive. That enables the use of a pattern
recognition algorithm and thus the identification of a large amount of different
vapours including ignitable liquids. 8 Multiple electronic noses were compared in a
review article and the article lists even the technologies they use and their
manufacturers. The article discusses the methods, their effectiveness and
applications from food factories to explosive detection. Future trends are also
discussed. 9 A Vapor-Sensitive Microsphere Array application that has been used in
the detection of volatile organic compounds and nerve agents was explored in a
study to detect ignitable liquids. Despite obtaining high accuracy in distinguishing
three different ignitable liquid classes in burned and unburned samples, additional
studies are needed in order to challenge the system with more realistic, simulated fire
debris samples. 10
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