SCIENZE NATURALI IN AMBITO FORENSE:L¿APPORTO DI STUDI GEOPEDOLOGICI E BOTANICI.

The role played by natural scientists in the modern forensic science is very real and important, above all in the crime scenes when buried remains, both strongly decomposed or skeletal, are found. The present Ph.D. research project is focused on the aspects of the Natural Sciences presently lacking of data in the forensic field, particularly Geopedology, but involving also other scientific disciplines such as Botany, Geophysics and, of course, Forensic Medicine. The Ph.D. project is entirely experimental and takes in account the diachronic study (for two years and a half) of two areas affected by the decomposition of buried pig carcasses, in order to find information which might clarify (and better define) the time elapsed since death (Post Mortem Interval) or since burial (Time Since Burial) and other interesting clues to assist criminal investigations. Most attention is paid, as regards the soil, to changes in micromorphological, compositional and elemental characteristics, with also particular interest to the organic matter and the Volatile Fatty Acids; while, as regards the botany, the attention is paid to variation and succession of different species and / or types of vegetation. The experimental work has been carried out using eleven pig carcasses (dead for reasons not related to the study) weighing between 50 kg and 90 kg, and simulating the mass of a human body. These were buried approximately at the same depth in two areas with different vegetation cover: an area of arid grass and a clear wood area. Together with the burial of the carcasses, phytosociological analyses were carried out in order to characterize the vegetation in the area; moreover, detailed field geopedological descriptions, followed by laboratory analyses, were performed for a complete characterization of the burial pits. The climatic parameters, as temperature and precipitation, where also recorded (and included in the database) for the entire duration of the experiments. At the intervals of one month and half, seven months, thirteen months, twenty-four months and thirty months, a couple of buried carcasses was exhumed for each of the two areas, using the traditional geoarchaeological excavation techniques; the autopsy of all carcasses and the studies of the skeletal remains were performed at the Institute of Legal Medicine and Insurances of the University of Milano. Together with each exhumation, geopedological and botanical samplings were carried out: the numerous samples were studied in different laboratories by means of various analytical techniques, taking also in account the results of the analyses of samples collected before burial. Bulk soil samples, were analysed in the laboratories of the Earth Sciences Department of the University of Milano and of the Environmental Sciences Department of the University of Milano - Bicocca, as follows: - Grainsize analyses; - Determination of pH in H2O and KCl; - Total Nitrogen and Organic Carbon analyses: - Quantification of Available Phosphorous; - Determination of Cation Exchange Capacity and Base Saturation. The detection of Volatile Fatty Acids was carried out through the use of gas chromatography coupled to mass spectrometry (GC-MS) in the laboratories of the Vegetal Production Department of the University of Milano. In addition, compositional analyses were performed with the aid of the scanning electron microscope (SEM-EDS) of the Earth Sciences Department of the University of Milano, by setting up a particular protocol for sampling and sample preparation called “Plug & Dust”. The experimental protocol took also in account the soil thin section micromorphological study on undisturbed soil samples, which is a technique never used before in the forensic context. In order to allow the micropedological study a new area with more clayey soils was subsequently identified; in this second experimental area were excavated two burials, containing five piglets each: on the undisturbed samples collected above and below the buried carcasses (exhumed after twenty months) the micromorphological study was conducted with the aid of the optical-petrographic microscope and cross-checked by SEM-EDS. In the same clayey area geophysical analyses, i.e. geo-electrical prospections, were carried out in order to follow the decomposition trends and the circulation / precipitation of body fluids in the soil. As regards the Botany, qualitative and quantitative reliefs of the species and of the covers of the areas were performed; moreover, tropisms and / or inhibitions, together with monthly / yearly growth rates have been taken in account. For each study area, small spots of confrontation, i.e. “false positive”, were produced by mechanical disturbance similar to the burials (i.e. excavation). The chosen analytical and sampling technique has been the Point Quadrat Analysis and the related statistical elaborations. The current study is the first Italian experimental project aimed to a holistic assessment of the geopedological and botanical changes induced by the presence of buried carcasses. The experimental project behind this doctoral work allowed to derive an indication of the overall alterations caused by the burial of a carcass in the natural environment, based on the contribution of Geopedology, Geoarchaeology, Botany and Geophysics. In the multidisciplinary analytical protocols usually applied in the event of discovery of a clandestine burial, the results of this work are implementing new techniques that can be successfully used in the forensic field. In this light, the achieved results, especially when cross-checked, are therefore very stimulating as regards the setting of new analytical protocols for: - The determination of time since burial (TSB); - The discrimination between primary and secondary burials; - The identification of corpses concealments. All the analyses and different approaches discussed and addressed in this work require extreme care when applied to real forensic scenarios; however, the protocols tested can be a piece of a large and articulated puzzle that depicts the major forensic case studies in which Natural Sciences (and Geopedology in particular) can be of help in solving problems or in answering some peculiar questions. It is important to understand that a science so rich in variability, as Geopedology is, has a great potential to reconstruct and solve various forensic cases. Many studies and experiments still need to be carried out to improve the knowledge of the specific processes, in order to give the correct answer to forensic and legal questions, together with the aim of reaching standardization for the analyses carried out.