Forensic microbiological analysis of the soil and the physical evidence buried in soil obtained from several towns in Istanbul

Crime scene investigation and the evidence obtained during this process are very important in solving judicial cases. Since soil may be transferred to a criminal or a victim in many of the criminal cases, it may provide important information to crime investigations as a carrier of evidence. Soil assumes different compositions and characteristic structures in different areas with the influence of many natural factors such as climate (humidity, temperature), basic material (main rock), relief (topography), living organisms and time. The versatile nature of the microbial distribution in soil gives us the chance to make use of microorganisms in identifying the soil. The identification of bacterial species in the soil and their metabolic activities may be used for the differentiation of soil samples. In microbiological terms, three groups of microorganisms make it possible to identify the soil and to specify the similarities and differences among different samples of soil. Making a comparison of the morphologies of fungus, bacteria and actinomycete colonies helps us identify the soil samples. This study has been planned to evaluate the importance of identifying the microorganisms in the soil for the forensic sciences. Our research covers 20 regions identified and marked outside the settlement area within the boundaries of İstanbul. Big and wide soil areas and forest areas were preferred. 4 types of physical evidence samples were collected from such areas was at the end of 1st, 2nd and 3rd month and then analyzed. The samples were embedded in order to physical connection to soil.10 g of soil sample and 4 pieces of physical evidence (fabric, rubber, metal, wood), sized 5x5 cm, buried 20-30 cm deep in the soil and contaminated with soil, were collected for analysis and stored in sterile conditions. The microbiologic identification analyses were done at the end of the predefined period and in the predefined order, using first phenotypic (microscopic, macroscopic etc.) then culture methods in combination with advanced diagnostic analyses by API and MALDI-TOF MS devices. In conclusion, the contribution of existence of microorganisms in the soil and on the sample physical evidences contaminated from soil, which is important on evaluation stage of criminal cases, was determined by way of microbiological analysis. % 69 bacteria , %31 fungus in the soil samples; % 75 bacteria, % 25 fungus on the physical evidences were identified and a database was set up. This study, was designed as a preliminary work in the solution of a judicial case, our results proved that soil-contaminated physical evidences can be used in a forensic criminal case. In addition these results will be able to be used for further geographical databases of Istanbul.