Examination of Firearms Review: 2007 to 2010 - Interpol

(spherical particles). The second generation, mostly used in the USA, contains
no Strontium, only aluminium, silicon and potassium, and its morphology is not
consistent with that of typical GSR particles – most particles being irregularly
shaped without any particular morphology. This is in contradiction with other
lead-free potassium-based primers from e.g. Winchester and Remington, which
do produce spherical particles.
Other occupational and environmental particles show the same elements and
morphologies as these types of primers, and can be detected on e.g. automobile
electricians, motor repair automechanics and petrol station attendants. Finally,
also problems occur for the shooting distance determination, as the regular
chemographic tests using rhodizonate do not react with the compounds in the
primer or, as is the case for the modified Griess test, will also react with other
nitro-compounds and hence can not be considered conclusive.
3.1.2 Trends and comparisons
Molina et al. (116) conducted an investigation of GSR testing results in suicide
cases with analysis by Inductively Coupled Plasma-Atomic Emission
Spectrometry (ICP-AES) and SEM/EDX. In this follow-up article on SEM/EDX
analysis of suicide victims (117), in which a total of 116 cases of undisputed
suicide by firearm were analysed, bulk analyses on 102 cases show a
comparable result: only 50% of the samples tests positive. The authors conclude
therefore that GSR analysis (by SEM/EDX or ICP-AES) can not be used to
determine whether a person has shot a firearm, since a negative result does not
signify that the person was not in contact with a shooting incident. Furthermore,
GSR can not be used to distinguish whether a gunshot wound is self-inflicted or
not. A positive result can be helpful, however, especially if used in concert with
other information of the individual case. As a final observation, there is no
significant difference between the performance of the SEM/EDX and bulk
analysis techniques. Both tests have their benefits and deficiencies.
3.1.3 Non-GSR sources of GSR-like particles
Since a number of years concern has existed about GSR-like particles originating
from a non-ballistic origin, which could lead to false-positive interpretation of the
analysis results. A number of publications have already treated particles
produced by car breaking systems and after the use of fireworks. These particles
do not originate from the use of primers. Two publications, however, treated the
characterisation of particles which arise after the non-ballistic use of primer
compounds.
Kinder and Provost (118) discuss a case where in a homicide, the suspect's
defence was built around the fact that he has contact with Hilti primer-based nailguns.
Although this type of equipment indeed uses a form of cartridges to drive
the nail, the primer from a nail-gun cartridge was found to contain only lead and
28