The punched-out tissue complex (skin-bone "imprimatum") in shots from captive-bolt guns: does it act as a secondary projectile?

From the first half of the twentieth century to the present day, injuries and fatalities from captive-bolt livestock stunners are a major topic in forensic medicine. The vast majority of cases account for suicides with the frontal, temporal, parietal, and occipital regions being the most common sites of entrance (in descending order of frequency). Due to the limited length of the bolt, the corresponding wound channel within the braincase is only several centimeters long. It has been a controversial subject for a long time, whether the skin-bone complex punched out by the conically grooved end of the steel rod may act as a "secondary projectile" being propelled beyond the actual path of the bolt. To answer this question, experimental shots from various types of captive bolt-guns were fired to simulants. Video-documentation employing a high-speed motion camera showed that the punched-out pieces of skin and bone did not move further than the bolt. Thus, a secondary extension of the total wound channel could not be observed. However, the suction effect caused by the bolt's rearward movement may induce a slight retrograde displacement of the skin-bone complex.

Influence of a soft tissue layer covering the kidney upon blunt impact.

Blunt abdominal organ injury is an abundant and relevant topic in forensic medicine, yet comparatively few experimental studies have been performed to quantify organ injury threshold parameters. The goal of this study was to relate an impact to a kidney injury determining an energy threshold while taking account of the influence of the overlaying soft tissue thickness. A model consisting of ballistic gelatin with an embedded filled porcine kidney was made such that a gelatin layer of 2 or 4 cm thickness covered the organ. An impactor was dropped on this model from different heights and the resulting organ damage was categorized according to the abbreviated injury scale (AIS). The 50% energy threshold for damage and the 50% energy threshold causing injuries ≥ AIS 3 were determined for the two protecting soft layers to be 22 J and 32 J and 27 J and 36 J, respectively. A finite element model was created to determine the strain energy densities at the depth of the organ's surface for these energies. The strain energy densities for the 50% damage thresholds were 88.9 mJ/cm3 and 86.7 mJ/cm3 for 2 and 4 cm and for the injuries ≥ AIS 3104.2 mJ/cm3 and 98.7 mJ/cm3. For forensic cases, this means that the thickness of the abdominal layers must be taken into account when the severity of an injury is used to draw conclusions about the applied impact strength.

How to recognise the traces left on a crime scene by a 3D-printed Liberator? Part 2. Elements of ammunition, marks on the weapons and polymer fragments.

The Liberator is a firearm that can be manufactured from its blueprints by the means of a 3D-printer. This handgun is composed of nineteen pieces: eighteen made of printed polymer and one metallic nail. This study focuses on the physical traces which can be found and exploited from a forensic point of view after the discharging of such types of pistols. Two main aspects have been investigated: (1) whether it can be inferred that a 3D-printed handgun was used when investigating a scene; (2) when presuming the use of a 3D-printed Liberator on a scene. Six Liberators were manufactured, assembled and discharged. The discharge occurred under controlled conditions to allow the collection of ballistics data and traces produced by the shooting. Elements of ammunition - cartridge cases and projectiles - that were fired during an experimental campaign appeared to carry polymeric materials (flakes, melted polymer or both). Besides, we observed that the fired ammunition elements lacked traditional marks left by the metal pieces of a conventional firearm. Indeed, the projectiles did not carry rifling marks and the cartridge cases were found torn or swollen. Fragments or larger pieces of polymer were found, mostly on the ground, near the location of the discharge, up to nine metres away. The impression of the cartridge case head stamp was also found on a part of the Liberator called the "hammer body". This study showed that the discharge of a 3D-printed Liberator is expected to produce traces that can be transferred onto and recovered from the printed firearm, the cartridge case, the projectile, the target, and the environment of the discharge. These traces are different from those left by conventional firearms. When found on investigation scenes, some of these traces can inform on the use of a 3D-printed handgun and contribute to the reconstruction of a shooting event involving such a weapon. This study suggests that the approach adopted when investigating a scene must be adapted in terms of traceology when the use of such firearm is suspected.

Rearward movement of the slide in semi-automatic pistols: a factor potentially influencing the configuration of muzzle imprint marks in contact shots.

A muzzle imprint mark is a highly diagnostic finding, which indicates a contact shot. In many cases, it also provides additional information on the type of the weapon used and on the way in which it was held at the time of firing. In semi-automatic pistols, some constructional elements constituting the muzzle plane move to the rear together with the slide, which may prevent them from causing a corresponding imprint close to the bullet entrance hole. The present study comprises 30 consecutive autopsy cases of fatal contact shots to the head inflicted with semi-automatic pistols. The imprint marks accompanying the entrance wounds were compared with the muzzle ends of the respective weapons both before and after retracting the slide. It turned out that in a considerable number of cases (3 out of 30), the retractable parts were not depicted or only to a minor degree as components of the imprint mark. In order to validate the presumed correlation, experimental shots were fired to composite models using pistols in which the movable and the stationary parts forming the muzzle plane were dyed with different paints. Thus, it could be demonstrated that the muzzle imprint preferentially mirrors the front sides of the stationary parts such as the barrel end, the recoil guide, and the gun housing. Immediately after discharge, the slide and the ballooning skin of the bullet entrance site move in the same direction. The stationary parts of the weapon block the expansion of the skin bulging towards the muzzle, so that the skin gets firmly pressed against them. The dynamic interaction between the gun and the entrance region resulting in a characteristic imprint mark could be visualized by the use of a high-speed motion camera recording test shots to different composite models.

How to recognize the traces left on a crime scene by a 3D-printed Liberator?: Part 1. Discharge, exterior ballistic and wounding potential.

The Liberator is a firearm that can be manufactured from its blueprints, using a 3D-printer. This weapon made of nineteen pieces - eighteen in printed plastic and one metallic nail - raises questions such as its ability to fire a round, its wounding potential and the traces produced by its discharge. In particular, knowledge must be gained to infer that a 3D-printed handgun was used, reconstruct the shooting event involving such handgun, and gather information related to the type of 3D-printed handgun used. This study focused on the traces that could orientate forensic investigations when the use of a 3D-printed Liberator is suspected. In a first step, the Liberator was investigated to study its behaviour during the discharge and characterize traces produced by the discharge. To fulfil this goal, some Liberators were printed and assembled. Six Liberators fired a round. The discharge of the weapons was done under specific conditions allowing to collect ballistics data and traces produced by the shooting. The results showed that the barrel tended to break between the ignition of the primer and the moment the projectile exited the muzzle. The speed of the projectiles reached 140m/s when the barrel broke, while it was about 170m/s when barrel remained intact. The trajectory of the projectiles was sometimes disrupted, and the projectile tumbled on itself. It was thus very difficult to characterize the trajectory. The cavity wound caused by the fastest bullet was typical of a handgun wound firing a FMJ projectile (penetration of 21cm in ballistics soap). On the other hand, the cavity caused by the slowest bullet was more representative of a splinter wound (penetration of 14cm in ballistics soap). The study of gunshot residues collected on adhesive targets showed the presence of unburnt particles and small perforations caused by polymer pieces that concentrated around the entry holes.

Assessment of a specifically developed bullet casing gun for the stunning of water buffaloes.

Water buffaloes and cattle differ considerably with respect to the anatomy of the head. As a result, captive bolt stunners often fail to reliably produce adequate loss of consciousness in water buffaloes and, thus, do not fulfill animal welfare requirements. The goal of the present study was to assess and validate a new stunning device for water buffaloes meeting animal welfare and occupational safety requirements. The newly designed bullet casing gun uses .357Mag/10.2g hollow point bullets and has additional safety features. Its effectiveness and usability were assessed under practical conditions in an abattoir as based on widely accepted criteria. Stunning resulted in deep unconsciousness in 19 out of 20 water buffaloes. One 9-year old male did not immediately collapse. Except for very old bulls, the device presented herewith provides a means to stun water buffaloes of both sexes effectively and reliably while keeping occupational hazards to a minimum.

Energy loss and impact of various stunning devices used for the slaughtering of water buffaloes.

Stock management of the Swiss water buffalo livestock results in the slaughtering of about 350 animals per year. As the stunning of water buffaloes still is an unresolved issue, we investigated the terminal ballistics of currently used perforating stunning devices. Cartridge fired captive bolt devices, handguns and a bullet casing gun were tested in a shooting steep by firing on bisected heads, forehead plates and soap blocks. Energy loss of captive bolts confirmed their inadequacy when used for heavy water buffaloes, notably adult males. As for the free projectiles, ballistics revealed that beyond the impact energy, bullet deformation has a strong impact on the outcome. Light 9mm Luger or .38 Spl bullets as well as large deformable .44 Rem. Magnum bullets should be avoided in favor of heavier .357 Magnum deformation ammunition. These data have been translated into the development of a new stunning device for water buffaloes meeting both animal welfare and occupational safety requirements.

A patterned abrasion caused by the impact of a cartridge case may simulate an atypical muzzle imprint mark.

In contact shots, the muzzle imprint is an informative finding associated with the entrance wound. It typically mirrors the constructional components being in line with the muzzle or just behind. Under special conditions, other patterned skin marks located near a gunshot entrance wound may give the impression to be part of the muzzle imprint. A potential mechanism causing a patterned pressure abrasion in close proximity to the bullet entrance site is demonstrated on the basis of a suicidal shot to the temple. The skin lesion in question appeared as a ring-shaped excoriation with a diameter corresponding to that of the cartridge case. Two hypotheses concerning the causative mechanism were investigated by test shots: - After being ejected, the cartridge case ricocheted inside a confined space (car cabin in the particular case) and secondarily hit the skin near the gunshot entrance wound. - The ejection of the cartridge case failed so that the case became stuck in the ejection port and its mouth contacted the skin when the body collapsed after being hit.

Magnetic resonance imaging and computer tomography of brain lesions in water buffaloes and cattle stunned with handguns or captive bolts.

Owing to the demand for genuine mozzarella, some 330 water buffaloes are being slaughtered every year in Switzerland albeit a stunning procedure meeting animal welfare and occupational safety requirements remains to be established. To provide a basis for improvements, we sized anatomical specifics in water buffaloes and cattle and we assessed brain lesions after stunning with captive bolts or handguns by diagnostic imaging. In water buffaloes and cattle, the median distance from the frontal skin surface to the inner bone table was 74.0mm (56.0-100.0mm) vs 36.6mm (29.3-44.3mm) and from skin to the thalamus 144.8mm (117.1-172.0mm) vs 102.0 (101.0-121.0mm), respectively. Consequently, customary captive bolt stunners may be inadequate. Free bullets are potentially suitable for stunning buffaloes but involve occupational safety hazards. The results of the present study shall be used to develop a device allowing effective and safe stunning of water buffaloes.

Fatal contact shot to the chest caused by the gas jet from a muzzle-loading pistol discharging only black powder and no bullet: case study and experimental simulation of the wounding effect.

In modern medico-legal literature, only a small number of publications deal with fatal injuries from black powder guns. Most of them focus on the morphological features such as intense soot soiling, blast tattooing and burn effects in close-range shots or describe the wound ballistics of spherical lead bullets. Another kind of "unusual" and potentially lethal weapons are handguns destined for firing only blank cartridges such as starter and alarm pistols. The dangerousness of these guns is restricted to very close and contact range shots and results from the gas jet produced by the deflagration of the propellant. The present paper reports on a suicide committed with a muzzle-loading percussion pistol cal. 45. An unusually large stellate entrance wound was located in the precordial region, accompanied by an imprint mark from the ramrod and a faint greenish discoloration (apparently due to the formation of sulfhemoglobin). Autopsy revealed an oversized powder cavity, multiple fractures of the anterior thoracic wall as well as ruptures of the heart, the aorta, the left hepatic lobe and the diaphragm. In total, the zone of mechanical destruction had a diameter of approx. 15 cm. As there was no exit wound and no bullet lodged in the body, the injury was caused exclusively by the inrushing combustion gases of the propellant (black powder) comparable with the gas jet of a blank cartridge gun. In contact shots to ballistic gelatine using the suicide's pistol loaded with black powder but no projectile, the formation of a nearly spherical cavity could be demonstrated by means of a high-speed camera. The extent of the temporary cavity after firing with 5 g of black powder roughly corresponded to the zone of destruction found in the suicide's body.

The varying size of exit wounds from center-fire rifles as a consequence of the temporary cavity.

To study the question whether and how the size and position of the temporary cavity influence the morphology and especially the size of a bullet exit wound, test shots were fired to composite models consisting of gelatine and pig soft tissue covered with skin (at the exit site). The dimensions of the composite model were determined such that the exit planes were located either at the level of the narrow channel or within the temporary cavity or behind it. The chronological sequence of wound formation and its relation to the current position of the bullet were documented by means of a high-speed camera. Test shots were fired from a distance of 10 m using 5.56 × 45 mm cartridges with full metal-jacketed pointed bullets (v 0 ∼ 912 m/s, E 0 ∼ 1,663 J). The study proved that the extension and position of the temporary wound cavity was decisive for the size of the exit wound: An exit plane within the cavity resulted in particularly large skin lesions, whereas the wound diameters were much smaller if the exit plane was located in front or behind the cavity. The exit hole reaches its maximum size only after the bullet has left the target synchronous to the staggered expansion of the temporary cavity.