Introduction
The documentation and interpretation of firearm injuries are routine in forensic casework. These tasks are performed not only for deceased victims in the context of autopsies, but also for living victims within the scope of clinical medicolegal examinations. In both situations, the macromorphological examinations are performed in conjunction with imaging methods [
1‐
7]. In the reconstruction of shooting incidents, projectile trajectory and shot range are important aspects that need to be determined. Commonly, the primary goal of these reconstructions is to allow the inclusion or elimination of various scenarios during the shooting incident. In the case of perforating bullet wounds, the bullet trajectory can, for example, be calculated by simple trigonometry from the measurements for the specific locations of the entry and exit wounds on the body. This approach is, however, only applicable if the bullet followed an essentially straight path through the body and was not deflected along its way [
8,
9]. When projectiles glance off anatomical structures such as bones or teeth, or when they tangentially pass through fluid-filled cavities, large deflections in trajectory are possible [
8]. Generally, the magnitude of these deflections is influenced by the interaction of various factors, such as construction-related properties of the projectile, velocity and energy of the projectile as it enters the body, trajectory of the projectile, transfer of energy from the projectile to the penetrated material, length of the wound channel, and exact location where the projectile encounters body structures [
8,
10‐
13].
In the following we report on an atypical wound trajectory through subcutaneous adipose tissue, in which the bullet followed a curved path, without being deflected by bone or organ structures.
Discussion
In the reported case, a woman sustained three intermediate-range shot wounds after being fired at from the driver’s seat on the left side of a car. From a medicolegal perspective, the bullet trajectories for a graze wound on the victim’s forehead and the fatal penetrating gunshot wound to the head were simple to reconstruct.
The wound track left by the third, tangential, bullet was, however, so unusual that we believe it merits reporting. In the trajectory analysis of this wound from 3D reconstructed CT data sets, the linear distance measured between entry and exit wounds was approximately 36 cm. In this straight trajectory through the body, the bullet would have had to traverse the thoracic and abdominal cavities; however, the actual wound channel was not found to pass through either of these cavities. The bullet had, instead, followed an approximately 40-cm-long, nonlinear trajectory though the subcutaneous adipose tissue. Contact with bone could be excluded as a reason for bullet deflection. The contusion in the medial lobe of the right lung and the hemorrhage in the adipose tissue around the right kidney were, therefore, likely caused by expansion of the temporary cavity around the wound channel.
In an attempt to explain this atypical wound trajectory, possible body positions of the victim, in addition to ribcage positions while breathing, were considered, such as that she may have twisted her upper body, or have leaned forward or slumped sideways when the shot was fired. To aid this elucidation attempt, a dummy was used during the main trial to explore all conceivable positions of the victim’s body at the moment the shot was fired. Even when possible contributing effects such as tissue compression while twisting—and hence local increase in tissue density or rigidity—were additionally taken into account, none of the explored body positions could satisfactorily explain the unusual trajectory. Moreover, due to the kyphosis and intervertebral ossification that were noted in the postmortem CT, the mobility of the victim’s spine was manifestly restricted. This circumstance also had to be factored into the trajectory analysis. In the CT scan, it could, moreover, be seen that the victim’s upper body remained noticeably bent forward even when the body lay in a supine (post-mortem) position. The virtual trajectory between entry and exit wounds would, hence, have passed through her thoracic and abdominal cavities also in this position.
After consideration of all circumstances, the only viable explanation for the atypical trajectory of the bullet through the body is to postulate that it was deflected from its straight path to a curved trajectory, without glancing off bone. This hypothesis is strengthened by the observation that the only visible alterations on the perforating bullet were similar to those that would be expected for a bullet from the same pistol that had been fired into gelatin. In all other respects, the bullet was undamaged. The findings in our case report also tie in with the reported results from experimental studies in which significant deflections in trajectory were found for bullets passing through homogenous soft-tissue simulants [
11,
12]. In the case of projectiles from long-barreled firearms, this phenomenon may be explained by tipping or yawing of the bullet along its track through soft tissues. The resulting asymmetrical distribution of pressure on the bullet nose would exert a lateral force on the bullet, which would cause lateral acceleration and, thus, deflection of the projectile from a straight path on its way through the tissue [
14]. Although this effect would be expected to be significantly less pronounced for short-barreled firearms, due to constructional properties, deflections of more than 6° for bullet tracks longer than 20 cm have been reported in the literature, depending on the combination of projectile and weapon [
11].
A further explanation that could be postulated for the atypical wound trajectory in our case is that the bullet may, after tearing through the skin (entry wound) and passing through the subcutaneous adipose tissue for a few centimeters, have traveled towards the skin again. Due to the shallow incidence angle, the bullet may then have failed to penetrate the dermis from below and exit the body. Because of the skin’s elasticity, the bullet may then have been forced to follow a path parallel to the dermis until it reached a point, on the medial axillary line, where the radius of the skin’s curvature decreased far enough to increase the bullet’s angle of incidence to the extent that it allowed the bullet to penetrate the skin and exit the body.
In all, the case we report here further exemplifies the necessity of exercising due caution in identifying bullet trajectories solely on the basis of the locations of entry and exit wounds, even for wounds through essentially homogenous soft-tissues. Where the circumstances permit, it may, therefore, be more expedient to identify and use deflection points on bone, or perforations in serous membranes, along the first 10 cm of the wound channel, instead of the exit wound, to calculate the bullet trajectory [
11]. Moreover, if CT data are available for the virtual identification of the wound trajectory, the difference between the supine position of the victim’s body during the CT scan and the victim’s actual position at the time the bullet was fired should be taken into account as a possible source of error in calculating the bullet trajectory [
15].
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