Reconstructing the time since death using noninvasive thermometry and numerical analysis

Abstract

The early postmortem interval (PMI), i.e., the time shortly after death, can aid in the temporal reconstruction of a suspected crime and therefore provides crucial information in forensic investigations. Currently, this information is often derived from an empirical model (Henssge’s nomogram) describing posthumous body cooling under standard conditions. However, nonstandard conditions necessitate the use of subjective correction factors or preclude the use of Henssge’s nomogram altogether. To address this, we developed a powerful method for early PMI reconstruction using skin thermometry in conjunction with a comprehensive thermodynamic finite-difference model, which we validated using deceased human bodies. PMIs reconstructed using this approach, on average, deviated no more than ±38 minutes from their corresponding true PMIs (which ranged from 5 to 50 hours), significantly improving on the ±3 to ±7 hours uncertainty of the gold standard. Together, these aspects render this approach a widely applicable, i.e., forensically relevant, method for thermometric early PMI reconstruction.

Individualised and non-contact post-mortem interval determination of human bodies using visible and thermal 3D imaging

“…Despite the accuracy of the PMIs determined using our individualised TFD-model, we additionally note that the model is currently composed of only two distinct tissue types (adipose and non-adipose) 27 . Individualisation of the virtual body's tissue distribution could be achieved by including detailed tissue information derived from post-mortem computed tomography (CT) scans 36,37 .…”

“…To this end, 3D heat exchange simulations were carried out for all bodies using a TFD model (Fig. 1e) 27 . Thermal properties (e.g., thermal conductivity, specific heat capacity etc.)…”

“…However, these approaches are yet to be validated experimentally on deceased human bodies. Therefore, we recently developed a numerical approach for thermometric PMI reconstruction that combines a comprehensive thermodynamic finite-difference (TFD) model and thermometry of the skin, which we validated on deceased human bodies 27 . In this approach, manually determined anthropometric data (lengths, diameters and circumferences of various body parts) are used to render a computational model of the body, consisting of 3D geometric shapes, assuming a straight posture.…”

MicroRNAs as Useful Tools to Estimate Time Since Death. A Systematic Review of Current Literature

“…Unfortunately, this scenario becomes more and more problematic as time goes by and PMI increases. All the available literature data about PMI can be summarized in two categories: the early post-mortem changes and late postmortem changes periods [49]. If the dead body is discovered within 24 h after the fatal event, this situation is called early PMI (EPMI) and it can be determined evaluating physical and biochemical changes occurring short after death such as body temperature, post-mortem rigidity and lividity, degree of putrefaction, corneal cloudiness and characterization of gastric contents [50,51].…”

“…The best way for data standardization is the evaluation of endogenous reference genes, especially mRNA markers (including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-actin, RPS-29, and IL-1β), nowadays considered suitable endogenous control markers in biochemical studies. Even if these molecular markers are routinely used, they degrade over time, losing some of their efficacy as indicators of PMI, particularly in uncertain environmental circumstances (i.e., high temperatures) [35,47,49,50,61].…”