Postmortem submersion interval in human bodies recovered from fresh water in an area of Mediterranean climate. Application and comparison of preexisting models

Purpose: The methods developed in recent years for the assessment of the Postmortem Submersion Interval (PMSI) have proven to be promising, but are strictly related to specific geographical areas or climates. The aim of this study is to assess the suitability of two of the most recent total aquatic decomposition scores (TADS) for the determination of the PMSI in bodies recovered from fresh water in an area of Mediterranean climate in the last 15 years. To do this, the correlation coefficient (r2) between PMSI and Accumulate Degrees Days (ADD) or PMSI and days was studied. Methods: The correlation between PMSI (expressed in days or in ADD) and the TADS was evaluated considering: (a) bodies recovered during the entire period; (b) bodies recovered during the cold season; (c) bodies recovered during the warm season. A linear regression analysis was set comparing the statistical significance of a model plotting TADS versus ADD, and another model plotting TADS versus PMSI (expressed in days) for both scores. Results: Scores were scarcely applicable when considering the entire casuistry, as regression models showed low r2 values, but both scores showed high correlations after dividing the cases into 2 groups. In fact, after performing the seasonal partition, we observed a strong correlation between PMSI and TADS, using either of the scores. Conclusion: This study helps increase the accuracy, reliability, and validity of PMI estimation in bodies recovered from freshwater in an area of temperate climate, such as Northern Italy, supporting the need to establish regionally-specific equations for estimating PMI in a forensic context.