Examination of Firearms Review: 2007 to 2010 - Interpol

In the context of standardization of the fingermark sampling protocols, the study
proposed by Croxton et al. showed that lipids are logically over represented in
“groomed” fingermarks (i.e., when the donors are asked to rub their fingers on their
face or hair prior the deposition of fingermarks) compared to natural marks (202).
Eighteen donors were asked to leave “natural” fingermarks and sebum-rich ones on
a non-porous substrate. All the fingermarks were immediately analysed using gas
chromatography coupled with a mass spectrometer (GC-MS). On average, fatty acid
content could be over represented by a ratio of 4:1, squalene by a ratio of 16:1, and
the total sebaceous mass by a ratio of 6:1, compared to natural marks. This over
representation in lipids could seriously compromise the validity of some published
results. It should be noted that the amino acid composition remained significantly
similar between the two kinds of fingermarks. Moreover, the relative abundance of
amino acids was consistent with previously published studies (212), with serine as
the most abundant amino acid followed by glycine, alanine and aspartic acid. Finally,
no correlation between the total amount of fatty acids and of amino acids was
observed in both kinds of fingermarks. This result seems logical since these
chemicals are secreted by different glands.
Soltyszewski et al. studied the effect of water on the recovery of fingermarks and
DNA profiling (209). For this study, 456 sebum-rich fingermarks were left by eight
donors, on glass (10 seconds of contact time, medium pressure). Additionally, four
different kinds of water (i.e., river, sea, tap, and distilled), two temperature conditions
(i.e., 5 and 20°C), and six immersion times (from one day to 42 days) were
considered. The samples were then dried, processed by three fingermark detection
techniques (i.e., aluminium and ferromagnetic powders, and cyanoacrylate), then
swabbed for DNA profiling. Fingermarks were successfully retrieved for items being
submerged in water for up to six weeks, with high success rates for one to seven
days of immersion. Ferromagnetic powder and cyanoacrylate fuming showed to be
more effective than aluminium powder. The quality of the fingermarks nevertheless
decreased as the immersion times increased, and as the water temperature rose
from 5°C to 20°C. Finally, no DNA profile could be obtained regardless of the tested
conditions.
Kerr et al. investigated the effect of water immersion on the efficiency of the
commonly used fingermark detection techniques (208). For this study, non-enriched
fingermarks were left on glass before being immersed in different water baths (i.e.,
cold, 50°C, or soapy) for varying times (i.e., five seconds and one minute). It should
be noted that the fingermark aging time (i.e., the time left between the deposition of
the marks and their wetting) has not been specified by the authors. We assume that
the freshly deposited marks were immediately rinsed after their deposition. Nine
fingermark detection techniques were compared (i.e., aluminium and gold powders,
small particle reagent – SPR, eosin blue, erythrosine B, physical developer - PD,
gentian violet, sudan black, and cyanoacrylate fuming) according to their ability to
reproduce ridge details. As a conclusion, the authors recommend to first air dry
wetted glass samples vertically, before processing them with either aluminium or gold
powder. If vertical drying is impossible, they recommend using SPR while the
samples are still wet. It should be noted that cyanoacrylate fuming gave poor results
on the dried samples, which is in contradiction with the above-described study (209).
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