Application of aquatic decomposition scores for the determination of the Post Mortem Submersion Interval on human bodies recovered from the Northern Adriatic Sea

Purpose: The decomposition process of human bodies in marine environment is not well understood, and it is influenced by external variables related to the geographical area where the body is submerged. We report the application of two decomposition scores, the Heaton's score and the van Daalen's score, on a casuistry of human bodies recovered from the Northern Adriatic Sea. The aims of this study are to verify whether the marine environment of a Mediterranean climate area may affect the applicability of both scores and to develop a prediction model that can be applied on bodies recovered in salt water. Methods: A retrospective study was performed on 61 human bodies recovered between 2005 and 2019 from coastal water of the Northern Adriatic Sea nearby the Italian regions Emilia-Romagna and Marche. For each of the 61 cases included, the Total Aquatic Decomposition Score (TADS) was calculated with the Heaton's score and the Van Daalen's score. The prediction model was assessed through multiple regression analyses, and the determination coefficients (r2) between TADS and PMSI (expressed in days) and between TADS and Accumulate Degrees Days (ADD) were studied. The prediction model was applied to the entire case sample, to bodies recovered during the warm season and to bodies recovered during the cold season. Results: All bodies were recovered floating, and a very poor scavenging activity was observed. The regression analyses showed a strong correlation between the TADS and the total case sample using both scores and both independent variables (PMSI and ADD). The determination coefficients were greater than 0.95 also when considering the total case sample. Discussion: The proposed prediction models are not significantly influenced by seasonality, contrarily to what observed on bodies recovered in fresh water in the same climate area. However, the ADD model, which also consider the water temperature, should be preferred for higher decomposition stages. This study helps increase the accuracy of PMSI estimation in bodies recovered from a marine environment of the Northern Adriatic Sea.