Volcanic sands and benthic Foraminifers in a forensic soil related to a murder case: Can these particles support intelligence for establishing soil provenance?

In the case of serious crimes, the contact of objects (such as shoes, boots, and clothes) with soil can determine thetransfer of materials that may represent an important physical evidence to be analysed in forensic soil science. In thisstudy, we better analysed composition of one forensic sample, related to a murder case (Romeo et al., 2013). Thesample was mostly formed by inorganic particles with a lower content in organic component (little stems, roots, seeds,and leaves). Most of the inorganic component was formed by marly-clayey aggregates. Inorganic component wasrepresented by mono- and polymineral silicate clasts and black amorphous grains showing a sandy to silty texture. Themain minerals were quartz, muscovite, feldspar, and biotite. XRPD analyses evidenced also the occurrence of minorcalcite, clinochlore, montmorillonite, and augite; XRPD indicated that the feldspar was anorthite. The main polymineralclasts were represented by sericite phyllites and gneiss. The EDX and XRPD analyses on the black amorphous grainsindicated that the glass derived from hawaiitic-type magma. Several mm-size fossils of marine environment, such asforaminifera (less than 30), or bioclasts of mollusks and gastropods were also found. Particularly foraminifera, smallerthan 2 mm in size, were mainly benthic. Amphistegina lessonii d’Orbigny was the most common species, followed inabundance by Elphidium crispum (Linnaeus). We found only one specimen, which can be assigned to Planulinaariminensis d’Orbigny. Small globigerinids were also found. Compositional data suggested that the forensic sample wasformed by a wide range of inorganic particles (in order of abundance: sedimentary, metamorphic, and volcanic) andfossils. The here presented data would suggest that the forensic soil presumably originated from a geological area wherethe three groups of rocks coexist. An important constraint was the presence of very peculiar volcanic clasts whosegeochemical features are compatible with Etna activity occurred during the last ten years. Within the sample there aremetamorphic clasts, too; they are widespread in the crystalline basements of the Internal Zones of the Alpine belt andcould therefore derive from the Calabria-Peloritani Arc. Finally, the sample contained fossils and marly-clayeyaggregates, which are generally recorded in Pleistocene to Recent formations that crop out along the Ionian andTyrrhenian sides of the Calabria-Peloritani Arc. Consequently the studied forensic soil could geographically derivefrom the Calabria-Peloritani Arc, in an area not too far from the coast and where Mount Etna volcanic ashes could alsobe present.