Verification of the exponential model of body temperature decrease after death in pigs

Area of Science:

• Forensic Science
• Thermodynamics
• Post-mortem interval estimation

Background:

• Current forensic medicine models for post-mortem body temperature decrease require validation.
• Existing models are often complex, utilizing multi-exponential functions for time of death estimation.

Purpose of the Study:

• To systematically evaluate the accuracy of post-mortem body temperature decrease models in pigs.
• To determine the optimal model and body sites for reliable time of death estimation.

Main Methods:

• Automatic temperature recordings over 24 hours in four body sites (eyeball, orbit soft tissues, rectum, muscle) in pigs.
• Analysis of temperature decrease plots using thermodynamic models, including single-exponential and two-exponential approaches.
• Statistical assessment of model significance considering intersubject variability.

Main Results:

• Temperature decrease in pigs followed a single-exponential thermodynamic model, consistent with Rainy's 1868 model.
• A second exponential term for intersubject variability was statistically insignificant.
• Multi-exponential models and individualized cooling curves did not improve estimation reliability.
• Eyeball and orbit soft tissues are suitable for early post-mortem measurements (up to 13 hours).
• Rectum and muscle tissues provide better estimations for later post-mortem intervals.

Conclusions:

• A single-exponential model is sufficient and reliable for post-mortem interval estimation using eyeball cooling up to 13 hours.
• Complex, multi-exponential models do not enhance the accuracy of time of death estimation in forensic practice.
• Eyeball and orbit soft tissues are recommended for early post-mortem cooling measurements, while muscle and rectum are better for later intervals.