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DETECTION OF GUNSHOT DISCHARGE RESIDUES
It is possible to detect on the back of the firing hand of individuals, who had discharged a weapon,
traces of the metals barium, antimony and lead, originating from the primer of the cartridge. Cotton
tipped swabs moistened with either 10% hydrochloric acid or 5% nitric acid are used to recover
residues for analysis by flameless atomic absorption spectrometry (FAAS) and neutron activation
analysis (NAA). Adhesive material is used to recover residues for analysis using scanning electron
microscopy and EDAX.
Problems to be aware of:
i. All three metals are not necessarily present in some rimfire primers.
ii. Neutron activation only detects antimony and barium, and must be used in conjunction with
FAAS to detect lead.
iii.NAA and FAAS are both quantitative elemental analytical methods which do not
distinguish the source of the metals. False positives are therefore theoretically possible.
iv.Although SEM with EDAX can potentially absolutely identify gunshot residue, often the
result is typical but not unique. In practice residues are detectable in 90% of persons who
have fired handguns, but only 50% of persons who have fired rifles and shotguns.
v. The quantity and distribution of the three metals can be described as consistent or not
consistent with gunshot residue and thus with firing a weapon.
vi. Residues on the palms of the hands may indicate a defence gesture, or alternatively the
handling of a previously fired weapon.
vii.In suicides residues are often detected on the non-firing hand used to steady the muzzle
against the body.
viii.Residues of barium alone may be the result of contamination with barium rich soil.
In the UK, firearms discharge residue kits are available from the Metropolitan Police Forensic
Science Laboratory, the Home Office Forensic Science Service Laboratory at Chorley and the
