Examination of Firearms Review: 2007 to 2010 - Interpol

fluorescence in an acidic media at low temperature. In contrast, Vinokurov et al.
(140) examined the possibility of a contamination of the victim’s clothing,
inducing a negative bias, for instance when the victim falls on the contaminated
surface between her and the shooter. However it was found that the transfer is
quite low and misinterpretation can thus only occur for relatively long distances (>
1 m) when few GSR are visualized in the vicinity of the hole.
3.2.3 Development of analytical techniques
Beside visual examination intrinsically subject to lack of precision, analytical
methods are developed to improve the accuracy of the results. Cagliano-Candela
et al. (141) used atomic absorption spectroscopy to quantify lead concentration
around bullet holes. A linear relationship was found between the firing distance
and the logarithm of lead amount in the outer ring around the hole.
In a similar approach, Sharma and Lahiri (142) used FTIR microscopy for
distance determination (7-30 cm) based on the concentration of nitroglycerine.
Reid et al. (143) took a look at the sampling dilemma: whether to use swabs or
stubs for GSR analysis by SEM/EDX. In a statistical analysis of the results of
using stubs and alcohol-imbibed swabs to collect GSR from hands, authors show
that the adhesive stub method is definitely better suited for collection of this
particulate material.
Souza Sarkis J. et al. (144) Further developed the use of sector field ICP-MS to
analyse lead, barium and antimony levels on test shooters and controls in a
study carried out using .38 revolver, and 9mm and .40 calibre pistols. Realising
that absolute quantification and recovery studies are of no use, the authors use
ternary plots to show a presence of the trace elements that can lead to
identification of GSR on shooters’ hands.
Finally, Rosenberg et al. (145) determined the detection time frame of inorganic
GSR by a preliminary field test using LASER-Induced Breakdown Spectroscopy
(LIBS). Although LIBS is a bulk analysis technique for inorganic materials, it can
be used, according to the authors, as a presumptive and inexpensive field test,
after which the SEM/EDX technique would complement it with its high specificity
for characteristic GSR particles. The authors claim that up to 5 days after firing, a
significant barium signal can still be measured on the hands of test shooters who
had been living normal lives, including hand washing and other day to day
activities.
3.3 Organic GSR
Next to the inorganic components of GSR, also the organic part of the residues is
more and more being studied for use in routine investigations. Where in the past
predominantly chromatographic techniques were developed (both in liquid and
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