The rate and quality of post-mortem hair root changes in relation to melanin content.

Hairs is a relatively environmentally resistant biological material that is often found at crime scenes. Human hair is more durable than other biological traces such as blood or urine, and its collection and storage does not require specific preservation procedures. Melanin is the hair pigment, which is the main determinant of hair colour. There are two pigments present in human hair: eumelanin, predominant in dark hair, and pheomelanin, responsible for red colour. Eumelanin is more resistant and has photoprotective properties, while pheomelanin is phototoxic and shows lower resistance to environmental factors. The differences in the properties of eu- and pheomelanin are the basis of the present study, which aimed to examine the rate and quality of taphonomic changes in hair roots in relation to the predominant melanin type, under the influence of selected environmental factors, such as soil pH, degree of exposure to solar radiation, temperature and water from a natural watercourse (river) and chemically pure water. Therefore, changes in blonde, dark, grey, red and dyed hair roots were microscopically documented for six months under the influence of the above factors. The results of the study indicated the strongest degradation potential among acidic soil and a riverine environment, as well as the protective role of eumelanin against environmental taphonomic factors. Degradation occurred most rapidly in the river environment, where microbial activity was additionally observed. Distilled water, exposure to sunlight and low temperature did not lead to decomposition changes. The results of our team's research provide the basis for an extended analysis of the changes occurring in hair under the influence of environmental factors in relation to melanin content.

Can plants indicate where a corpse is buried? Effects of buried animal tissues on plant chemistry: Preliminary study.

The bodies of murder or accident victims may be concealed below ground to cover up the crime by the perpetrator. During decomposition, nutrient-rich substances that may affect the surrounding environment enter the soil. The logical effect of local changes in soil biogeochemistry should be an impact on the vegetation occurring in a cadaver decomposition island (CDI). Nitrogen, phosphorus, and potassium compounds, which are common plant fertilizers, have received most of the attention in studies using animal remains, but many other elements such as trace metals enter the environment during decomposition of carcass. Furthermore, the decomposition of carcasses can locally affect environmental parameters such as humidity, soil pH, and oxygenation. This study examined whether animal tissues buried in soil could affect vegetation. The experiment was conducted in an open space in southern Poland, using limbs from Sus scrofa domestica. Four test plots were set up: I - clean soil (control plot), II - control plot + urine (potential nitrogen source), III - animal tissues buried at 20 cm depth and IV - animal tissues buried at 10 cm depth. Seedlings of Begonia semperflorens were planted in all four plots. After the end of one full growing season, plant measurements were obtained, and soil and plant material samples were taken. The presence of limbs, regardless of depth, had a very positive effect on plant development. Chemical analyses were performed to determine which compounds could have affected the vegetation. In addition to the standard analyses for nitrogen, phosphorus or potassium, levels of copper, iron, manganese, zinc and magnesium were also determined. The elemental content in the soil and plant material from different plots varied. Interestingly, despite the more intense vegetation, lower levels of elements were found in the soil and leaves of plants from the experimental than from the control plots. In many cases, there were clear differences in the contents of elements between the experimental plots. This could indicate, for example, different phases of animal tissue decomposition, which could have been caused by the different depths at which the remains were buried. As concentrations of elements in soil and plants can change significantly over time, material will need to be collected at regular intervals in any future studies. However, it is still unknown what exactly is responsible for the enhanced plant growth within a CDI and whether there are markers that could be helpful in identifying the burial sites of carcasses on the basis of comprehensive vegetation analysis.