The possibilities and limitations of comparative diatomaceous analysis for confirming or excluding the site of an incident - Case studies.

Diatoms (Bacillariophyta) are unicellular photosynthetic organisms commonly occurring in aquatic habitats on Earth. Their autecology makes them almost perfect indicators of environmental conditions and so have high potential for use in forensics. Both eurytopic and stenotopic species are important in site identification: eurytopic forms due to their abundance, and stenotopic forms due to their narrow range of tolerance to environmental conditions. Their presence can hence provide a clear insight into an ecosystem and its microhabitats. The diatoms are useful as significant indicator in diagnosing of drowning. However, to definitively link a corpse with the place where it was found and to indicate whether this was also the crime scene, it is essential that any comparative diatomaceous analyses are performed correctly. The following study presents selected cases in which a comparative diatomaceous analysis was performed. In all cases, the biological samples secured during the autopsy were compared with environmental samples collected from the site of the cadaver disclosure. Our findings show both the possibilities and limitations of using this method in forensics. These forensic investigations need close collaboration between coroners and diatomology experts. It is crucially important to reveal whether the place of corpse finding is the same as the place of drowning.

Diatoms from inland aquatic and soil habitats as indestructible and nonremovable forensic environmental evidence.

Environmental analysis of soil, water, and plants plays a key role in the criminal investigation process, as it not only provides information about the course of the crime, but it can also elucidate the connection between the offender, the victim, and the environment. One particularly useful way of linking the victim and offender to a specific environment is by analyzing their clothing for the presence of diatoms. The present research was conducted upon field experiments. Firstly, it examines the variability of diatom and the quantitative analysis of diatom communities in designated places, each at an increasing distance from the aquatic ecosystem. Secondly, it analyses the differentiation of the structure of diatom communities in designated environments located close to each other. Thirdly, it examines the diatom colonization of selected substrates: cotton, chamois leather, and sponge. Finally, it confirms whether the diatoms which transfer to socks after contact with the selected environment reflect the structure of the diatom communities in that environment, even after the socks had been washed. Our findings indicate that diatom communities vary considerably, even between environments separated by short distances, and that objects placed in a particular environment are colonized by diatoms that reflect the environmental samples, irrespective of the substrate. In addition, after contact with a specific aquatic ecosystem, sock material retained diatom collections that reflected the environment samples, even though the time of exposure was very short and after the socks had been washed. This provides valuable information that can be used as forensic evidence.