Post-autopsy computed tomography. Pros and cons in a firearm death

Post-mortem CT in the investigation of homicides

AIM

To investigate the reliability of post-mortem computed tomography (PMCT) in a case series of homicides involving blunt-force, sharp-force, and ballistic trauma.

MATERIALS AND METHODS

The study investigates 16 homicide cases that underwent PMCT before autopsy. Two radiologists assessed the PMCT examinations and the data were compared to the forensic pathology findings. Data were organised in broad categories: foreign bodies, external injuries, soft-tissue and organ injuries, fractures, air in cavities, fluid collections, random pathology, and wound track. Findings were organised by systems: head and neck, thorax, abdomen and pelvis, extremities. Cohen's kappa statistics were used to assess observer agreement.

RESULTS

Six gunshot-related homicides (37.5%), seven sharp-force-related homicides (43.75%), two blunt-force-related deaths (12.5%), and one homicide due to mechanical asphyxia (1.25%) were analysed. A total of 64 fractures were reported by the pathologists, 67 by radiologist 1 and 68 by radiologist 2. Agreement was deemed substantial in all cases. Pathologists failed to report gas in cavities while radiologists underreported superficial injuries.

CONCLUSION

An overall observation was that less accurate findings were produced by the blinded radiologist in comparison to the non-blinded one. The extremeness of homicides obscured the interpretation of PMCT leading to the observed discrepancies. The combination of PMCT and autopsies is deemed optimal when investigating homicidal events.

X-ray analytic microscopy with CT-guided sample extraction to analyze potential projectile fragments in a dead serow

In forensic pathology, it is important to detect and recover as evidence residual metal particles and projectiles when evaluating potential gunshot wounds. This process can be challenging when the bullets are fragmented. This report presents our experience using multiple modalities to analyze the wound of an illegally killed Japanese serow (Capricornis crispus) found in a mountainous region without its head and hind limbs. We performed postmortem computed tomography (PMCT) and necropsy that showed a distant-range gunshot wound of the neck likely created by a centerfire rifle. A postmortem cut through the neck and absent head precluded a complete evaluation. To determine the composition of the metal-like fragments in the neck, sampling and metal analysis were performed in two ways. Samples extracted from the exposed wound surface without CT guidance were analyzed directly using inductively coupled plasma mass spectrometry (ICP-MS). Samples from the bone, muscles, and cervical cord extracted under CT guidance were analyzed using x-ray analytic microscopy (XGT-9000, HORIBA, Kyoto, Japan). In wound surface samples, silicon and iron were detected as the main components on ICP-MS, suggesting that the materials were gravel. The samples taken under CT guidance and analyzed with XGT-9000 revealed that the high-density CT areas were mainly composed of lead. Combining CT-guided sample extraction and XGT-9000 can be useful for retrieving true projectile fragments and avoiding the confusion created by erroneously sampling non-projectile surface materials.

Postmortem CT and autopsy findings in nine victims of terrorist attack

In a foreign country, a religious terrorist group raided a restaurant, using pipe bombs, sharp-edged weapons, and various types of firearms (handguns, submachine guns, and AK-47 assault rifles) loaded with normal and prohibited bullets to kill foreigner customers, some of whom were Italian tourists. Local pathologists performed forensic autopsies on the bodies, but we were asked to perform additional external examinations, postmortem computed tomography (PMCT) scans, and then a second round of complete autopsies on nine victims (5 females and 4 males). Four victims had slash wounds inflicted by sharp-edged weapons, mostly localized in the head and neck. All but two victims had gunshot wounds. Finally, three casualties had injuries caused by the explosion of improvised explosive devices. In all cases, PMCT was a reliable source of information and provided strategic guide during autopsies, helping identify and describe the injuries and thus reconstruct the events. Therefore, in these cases, we suggest integrating the autopsy findings with the postmortem radiological data.

Influence of bullet type and muzzle-to-target distance on trajectory deflection through a soft tissue simulant

The influence of two different variables on deflection was studied with 9mm Luger calibre bullets, fired through ballistic gelatine. To test whether bullet type affects trajectory deflection, bullets of four different types were fired (20 shots per type) through 25cm of 10% gelatine at a 5m muzzle-to target-distance. A Kruskal-Wallis test showed that the deflection of at least one bullet type was significantly different (p<.001, significance level of 0.05) from the deflection of the other bullet types. To test whether muzzle-to target-distance affects trajectory deflection, additional shots were fired with one of the four bullet types (7.5g FMJ-RN) at 1 and 15m muzzle-to target distances (20 shots per distance), again through 25 cm of 10% gelatine. A Kruskal-Wallis test showed that there was no significant difference (p=.72, significance level of 0.05) in deflection between the three muzzle-to target distances of 1, 5 and 15m.

Interpol review of forensic firearm examination 2016-2019

This review paper covers the relevant literature on forensic firearm examination from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

A heart of stone: an autopsy case of massive myocardial calcification

A case of massive calcification of the myocardium is presented that was diagnosed by postmortem computed tomography (PMCT) and confirmed by conventional autopsy. There are two types of pathologic calcification, dystrophic and metastatic. Massive calcification of the myocardium is associated with variable clinical outcomes, including sudden unexpected death. A 53-year-old man was found after he collapsed beside a walkway. He was transferred to hospital and died approximately two months later. To investigate the cause of death, PMCT and conventional autopsy were performed, which revealed massive calcification of the myocardium, a very rare finding at autopsy. Massive myocardial calcification was one of the possible causes of his collapse. PMCT may be a useful diagnostic tool for detecting massive calcification of the myocardium following sudden cardiac death.