Re-oxygenation of post-mortem lividity by passive diffusion through the skin at low temperature

The spectrum of presentations of unintentional carbon monoxide poisoning

Carbon monoxide (CO) is an odourless and tasteless gas which can be produced by the incomplete combustion of carbon-containing fuels. Compared to vehicular CO suicides, unintentional cases (excluding those related to fires) are much less common. Increased education surrounding the risks associated with the accumulation of CO in enclosed spaces has contributed to a reduced incidence of unintentional CO poisonings. However, such cases may remain undetected, particularly in domestic and recreational settings where scene findings are often non-specific. The current study of unintentional CO poisonings in South Australia and the Northern Territory, each with a unique climate (Mediterranean and tropical respectively), demonstrated differences in the circumstances of death. Several cases where individuals used carbon-producing fuel sources for heat, both in domestic and vehicular settings and without adequate ventilation, resulted in fatal outcomes. Less common scenarios involved faults in equipment (e.g. a hot water heater), vehicle faults resulting in the accumulation of fatal levels of CO in enclosed spaces, and inadvertent introduction of CO into a diving oxygen supply in a recreational aquatic setting. In ascertaining the cause of death, other considerations include the potential role of underlying chronic cardiovascular and respiratory disease and age which may increase an individual's susceptibility to CO toxicity. Understanding the wide variety of presentations and contributing factors in cases of fatal CO poisoning including consideration of climate-specific differences in domestic and extra-domestic settings may enable improved detection at autopsy.

Predictive equation to estimate post-mortem interval using spectrophotometric blood-colour values

Forensic pathologists use post-mortem phenomena to estimate the post-mortem interval (PMI). We have reported on the usefulness of post-mortem lividity spectrophotometric values to estimate PMIs. Here, we focused on blood colour, looking for associations between blood colour, age and PMI. We generated predictive equations for blood-colour values and the PMI. We included data from a total of 129 cadavers (84 males and 45 females). We measured the colour of 124 left ventricular blood ( L*_l, a*_l, b*_l), 123 right ventricular blood ( L*_r, a*_r, b*_r) and 57 femoral blood ( L*_f, a*_f, b*_f) samples. We found no significant associations between blood colour and age or between blood colour and the PMI, but the values of a*_l, b*_l, a*_r and b*_r were significantly increased with increased age, and those of L*_f, a*_f and b*_f were significantly decreased with increased PMI. We created equations to estimate blood colour. The equations for femoral blood colour had higher adjusted R² values and lower root mean square error values than those for left and right ventricular blood colours. We generated equations to estimate PMIs using blood-colour values and autopsy findings. Our estimated PMIs up to 67 hours had accuracies within 8.84 hours, without measuring post-mortem lividity colour or considering the age of the deceased. This is the first study to estimate PMIs based on blood-colour spectrophotometric values.

Investigation into the potential for post-mortem formation of carboxyhemoglobin in bodies retrieved from fires

The forensic investigation of a deceased person retrieved following a fire includes measuring carboxyhemoglobin. A carboxyhemoglobin saturation above 10% is considered indicative of respiration during a fire, implying the person had been alive. This relies on the assumption that carbon monoxide will not diffuse into blood used for toxicological analysis. This project investigated the potential for carbon monoxide to passively diffuse into a body and if carboxyhemoglobin levels could become elevated post-mortem. Stillborn piglets with intact skin were exposed to carbon monoxide. Carboxyhemoglobin formed in the hypostasis of the skin, but carboxyhemoglobin levels in blood from the heart and chest cavities were not significantly elevated. However, defects in the skin over body cavities (producing breaches to replicate cases with stab wounds or heat damage) resulted in cavity blood carboxyhemoglobin levels above 10%. A review of fire death cases in South Australia 2000-2015 was performed to determine the origin of the blood samples used for toxicological analysis and the incidence of cases with breaches of body cavities. This revealed a small number of cases in which blood from the cavities had been analyzed when cavity breaches were present. Thus, there is a potential for significant elevation of carboxyhemoglobin saturation post-mortem in forensic casework involving bodies retrieved from fires.

Review of autopsy reports of deaths relating to fire in South Australia 2000-2015

It has been noted there are gaps and inconsistencies in data pertaining to fire related deaths in Australia, which poses difficulties for analysis of national statistics. A search of post-mortem examination reports at Forensic Science SA from 2000 to 2015 revealed 275 cases regarded as fire related in which the body had been involved in a fire. The autopsy reports were evaluated to determine parameters including the location of the fire event, age and sex of victim, as well as the presence of soot in the airways and cherry-red coloration to the blood and/or organs, in addtion to toxicological levels of carboxyhemoglobin and alcohol. Fire events were clasified as structural, transportation or open air in type. Males were more commonly victims than females, especially in transportation fires, where males aged below 50 years were most at risk of death. Carboxyhemoglobin levels tended to be lower in victims of transportation fires. This study has confirmed that presence of soot in the respiratory tract and cherry-red coloration of a body retrieved from a fire are both linked to an increased level of blood carboxyhemoglobin. These findings significantly contribute to the documentation of fire deaths in Australia.

Similarity analysis of spectra obtained via reflectance spectrometry in legal medicine

In the present study, a series of reflectance spectra of postmortem lividity, pallor, and putrefaction-affected skin for 195 investigated cases in the course of cooling down the corpse has been collected. The reflectance spectrometric measurements were stored together with their respective metadata in a MySQL database. The latter has been managed via a scientific information repository. We propose similarity measures and a criterion of similarity that capture similar spectra recorded at corpse skin. We systematically clustered reflectance spectra from the database as well as their metadata, such as case number, age, sex, skin temperature, duration of cooling, and postmortem time, with respect to the given criterion of similarity. Altogether, more than 500 reflectance spectra have been pairwisely compared. The measures that have been used to compare a pair of reflectance curve samples include the Euclidean distance between curves and the Euclidean distance between derivatives of the functions represented by the reflectance curves at the same wavelengths in the spectral range of visible light between 380 and 750 nm. For each case, using the recorded reflectance curves and the similarity criterion, the postmortem time interval during which a characteristic change in the shape of reflectance spectrum takes place is estimated. The latter is carried out via a software package composed of Java, Python, and MatLab scripts that query the MySQL database. We show that in legal medicine, matching and clustering of reflectance curves obtained by means of reflectance spectrometry with respect to a given criterion of similarity can be used to estimate the postmortem interval.