Polline giallo: la palinologia applicata alle scienze forensi

This paper is an overview of the principles and perspectives of Forensic Palynology, largely based on both general palynological assumptions and on the knowledge and experiences that the major international experts in this subject, Dallas Mildenhall, Patricia Wiltshire and Vaughn Bryant, shared in the last international congresses. In this moment, they are the few experts which spend time expressively to divulgate this science. They are actually involved in the investigations and surveys about criminal facts by the Security Forces, respectively, of New Zealand, Great Britain and USA.Pollen grains are a great survey’s instrument, but although this subject is treated since fifty years or longer, the two first Forensic Palynology International Meetings were held in 2004. Mildenhall and his colleagues underline the fact that main questions on this subject are: “How this science works, which are its rules, and why the use of forensic palynology in a systematic way is so important”. In general, two main features bring pollen analysis to be a very valuable tool in different research and applicative fields: a) each species has a typical pollen morphology; b) pollen grains have a very resistant external wall, the exine. Only fire and oxidation can completely destroy pollen grains, while the microbiological attack and the wet variations in the substrate can hard on or get the exine thinner. A Reference Pollen Collection must support the pollen identification. Basic assumptions for correct interpretation come from both knowledge on botany, and on pollen production and transport characteristic of each species. Archaeological and palaeoclimatic recontructions, air and food quality control are partly based on pollen analysis. Experiences in these fields give to the forensic palynologist the possibility to be supported in his analysis by a theoretical and methodological background, useful to follow the pollen traces in forensic cases. The continuative involving in forensic cases for pollen sampling and analysis could drive the interpretation quality to higher levels. Collecting data analysis, pollen lists and spectra bring information about plant sources linking them with persons, events, places and seasons. This helps to answer the questions of “where?” and “when?” a crime has been committed.Moreover, palynology is a multidisciplinary science, and can give more detailed answers when it is complementary used with other sciences like geology, biology, meteorology, legal medicine, etc... As important instrument of crime solving would be used like one element of the Environmental Profiling. A forensic palynologist has to perfectly know the crime scene or the place of finding, and has to personally sample on the field some control samples, having a perfect knowledge about the sampling scene and objects. Comparison of pollen spectra from different samples is the base of palynological investigation. The more samples will be examined the more detailed pollen interpretation will be performed.So, the aspect that bring more difficulties to the systematic use of pollen analysis in the criminal investigations is the correct sampling problem and the presence of a palynologist on the crime scene. Palynology follows the Evidential Paradigm assuming that it is possible to infer a whole history by few elements, and the analysis must be trained without preconceptions, because the information that pollen analysis will bring is unpredictable. Pollen spectrum can afford remarkable information, but frequently the more interesting inferences come from abundant, or clustered, or in generally key evidence, pollen.In this paper, some case examples of pollen as important clue helping the investigations are reported such as the ‘yellow rains’, or the pollen marker of displacements or travels, witness of aggressions or robberies. Moreover, how the palynological method from other applicative fields, such as archaeobotany and melissopalynology, can be useful to give a contribution to the forensic sciences is discussed. This was made in order to increase the trasmission and the exchange of informations between Security Forces and botanists.