Documentation of the Body Transformations during the Decomposition Process: From the Crime Scene to the Laboratory

Forensic science is defined as the application of scientific or technical practices to the recognition, collection, analysis, and interpretation of evidence for criminal and civil law or regulatory issues. A combination of computer science in the field of 3D reconstruction and molecular biology science and techniques were employed in this research aims to document and record a complete picture of the body decomposition process including the changes of the microbiome over the decomposition process.

In this thesis, the possibility to reconstruct the crime scene and the decomposition process was investigated. In addition, a 3D model aiming to integrate the biological and thanatological information was generated. The possibility of utilising Autodesk 123D Catch software as a new tool for 3D reconstruction of a crime scene was thoroughly evaluated.

First experiments demonstrated that the number of photos required to obtain the best result was specified to be from 20 to 30 photos as a minimum. In addition, significant experiments were performed in different conditions of sizes, locations, and different involved materials. The measurements were obtained from the models using the same software were compared with the real measurements of the tested objects. The result of the correlation between real and estimated measurements showed a very strong agreement ranging from 0.994 to 1.000.

With reference to the documentation of the decomposition process, there are different factors, intrinsic and extrinsic, have been reported affecting the decomposition of a carrion/body. These factors mainly interact with the rates of the biological and chemical reaction happening after death. The biological reactions are mainly due to the activity of microorganism and insects. Pigs (Sus scrofa domesticus) were used as a model for human studies and the results obtained have been applied to other mammals without considering the effect of fur on the decomposition process and on the insect and microbial colonisation. In order to investigate this point, rabbits (Oryctolagus cuniculus) with and without fur were used in two sets of experiments at Huddersfield in summer 2014 and in spring 2015.

The results obtained in this study showed a similarity of the decomposition stages between animals with and without fur. However, the decomposition process was faster during the summer due to the fast of insect colonisation and activity. In addition, the entomological data collected during the summer and spring experiments were demonstrated that the same taxa nearly were present in both seasons, except Hydrotaea (Diptera, Muscidae), which was
presented only in the summer experiment, moreover, only one sample of Lucilia sericata (Calliphoridae) was detected in the spring season. Differences in colonisation time were observed only in spring experiment; animals without fur were colonised two days before animals with fur. The season could have affected the insect’s activity and the spread of the decomposition volatiles.

The microbial communities during the decomposition process were investigated using BIOLOG EcoPlate™ and the hypervariable V1-3 region of 16S rRNA gene was used for their molecular identification based on pyrosequencing. Eurofins Genomic Operon using 454-GS Junior pyrosequencing platform (Roche) carried out these analyses.

The functional diversity of the bacterial communities on all carcasses samples showed a considerable variability depending on the stage of the decomposition and the sampling region (Oral cavity, skin and interface-sand-carrion) in both seasons. Furthermore, over the molecular analyses of bacterial communities at the phylum level, four main phyla of bacteria were detected among analysed carrion during the decomposition process. These phyla were changed significantly during the stages of the decomposition and between sampling regions. While no difference was observed due to presence or absence of fur. On the other hand, the analysis at the family level was able to highlight differences at the temporal scale but as well as carrion with and without fur. The statistical analysis results showed a significant difference in the bacterial community family distribution among the presence of fur and among the decomposition stages, with significant differences among sampling regions and seasons.