Evaluation of soil chemical properties during cadaveric decomposition and its applications to forensic chemistry

Abstract

The estimation of the Post-Mortem Interval (PMI) is a primordial parameter in the investigation of crimes against life. In tropical climate areas, the cadaveric decomposition occurs in an accelerated form, preventing the PMI estimation by usual methods. Understanding how different circumstances affect the cadaveric composition is very important to develop methods that enable the PMI estimation in several climatic conditions. One of the alternatives, however not much explored in Brazil, refers to the use of soil chemistry for the determination of longstanding PMIs. In this research, variations in soil chemical properties were monitored during swine carcasses cadaverous decomposition in a tropical forest area in order to recognize patterns and evaluate the applicability of these by the criminal expertise. Among the evaluated characteristics are the levels of pH, inorganic nitrogen (ammonia and nitrate), total nitrogen, carbon nitrogen proportion (C: N), exchangeable aluminum, available phosphorus and macro and micronutrients. The results showed distinct variations according to the decomposition phases observed and also to the way the carcasses were deposited in the study environment (above or below the soil), evidencing the possibility of using these variations in the development of models for the prediction of postmortem intervals lasting up to 67 days. © 2018 Secretaria Regional do Rio de Janeiro da Sociedade Brasileira de Quimica. All rights reserved.