MicroCT detection of gunshot residue in fresh and decomposed firearm wounds

Abstract

Gunshot residue (GSR) evidence may be altered or obscured by after-death events such as putrefaction, autolysis, and/or damage by animals. The present study aimed at evaluating and comparing the amount and differential distribution of GSR utilizing microcomputed tomography (microCT) analysis of fresh and decomposed gunshot wounds. A total of 60 experimental shootings at three different firing distances (5, 15, and 30 cm) were performed on human calves surgically amputated for medical reasons. Thirty specimens (10 for each tested distance) were immediately formalin-fixed, while the other 30 specimens were enclosed in a cowshed for 15 days, before formalin fixation (air temperature ranging from 11°C to 38°C). MicroCT analysis with three-dimensional image reconstruction detected GSR particles in all the investigated entrance wounds. In fresh specimens, GSR was concentrated on the skin surface around the entrance hole and in the epidermis and dermis layers around the cavity, while in decomposed specimens, the high density particles were detected only in the dermis layer. No GSR was detected in exit wounds of both fresh and decomposed specimens regardless of the tested firing distance. Statistical analysis demonstrated that also in decomposed wounds the amount of GSR roughly correlated with the distance from which the gun was fired, exhibiting, however, a higher variability than in fresh samples. The obtained results suggest that microCT analysis can be a valid screening tool for differentiating decomposed entrance and exit gunshot wounds.

An unusual case of “dyadic-death” with a single gunshot

“…[13,14]. To the best of our knowledge, however, microCT has never been applied to the analysis of firearm wounds to the head/skull [15], where a bone contamination may occur.…”

“…In order to verify the potential utility of microCT in that scenario, we analysed the three excised skin wounds of the reported case (2 entrance and 1 exit lesion), following our previously described protocol [10,13,14].…”

Micro-CT features of intermediate gunshot wounds covered by textiles

“…Beside visual inspection, chemical investigation, immunohistochemistry, and scanning electron microscopy coupled with energy-dispersive X-ray analysis, which are widely used tools for GSR identification, in the last decade, microcomputed tomography (micro-CT) has been applied to the identification and quantification of GSR around and inside the gunshot wound cavity [6][7][8][9].…”

Performance of post-mortem CT compared to autopsy in children

“…Post-mortem imaging (PMI) methods, including conventional radiography, computed tomography (CT) with or without contrast agent injection, and magnetic resonance imaging (MRI), have been applied and evaluated in many cases, including the detailed analysis of traffic accidents [3][4][5], detection of sources of bleeding [6,7], bone age estimation [8,9], gunshot injuries [10][11][12][13], and deaths occurring during or shortly after surgery [14]. PMI may add substantial information to the results of conventional autopsy and, in some cases, may serve as a non-or minimally invasive alternative method to conventional autopsy, especially if conventional autopsy cannot be performed.…”