Predicting the postmortem submersion interval for human remains recovered from U.K. waterways

Area of Science:

• Forensic Science
• Environmental Science
• Toxicology

Background:

• Accurate estimation of the postmortem submersion interval (PMSI) is vital in forensic investigations, particularly for bodies recovered from aquatic environments.
• Existing methods for PMSI estimation in riverine settings, especially in the UK, require refinement for improved accuracy.
• Decomposition rates are influenced by environmental factors such as water temperature and submersion duration.

Purpose of the Study:

• To enhance the accuracy of postmortem submersion interval (PMSI) estimation for human remains recovered from rivers in the United Kingdom.
• To investigate the relationship between decomposition levels, water temperature (accumulated degree days - ADD), and submersion duration.
• To develop a predictive model for PMSI based on observed decomposition and environmental data.

Main Methods:

• Data were retrospectively collected from 187 cases over 15 years involving bodies recovered from the River Clyde, River Mersey, and associated canals.
• Decomposition was quantified by scoring the overall observed decomposition in each case.
• Statistical analysis, including linear regression, was used to correlate decomposition levels with accumulated degree days (ADD) and submersion duration.

Main Results:

• Both the duration of submersion and accumulated degree days (ADD) significantly influenced the rate of decomposition.
• No significant differences in decomposition patterns were observed between the different waterways studied (River Clyde, River Mersey, canals).
• A single linear regression model was successfully developed to predict ADD from observed decomposition, enabling improved PMSI estimation.

Conclusions:

• The developed linear regression model provides a more accurate method for estimating the postmortem submersion interval (PMSI) in UK riverine environments.
• Decomposition is a reliable indicator for estimating submersion duration when combined with temperature data (ADD).
• This research offers a valuable tool for forensic investigators working with aquatic recovery cases in the United Kingdom.