Fracture energy threshold in parry injuries due to sharp and blunt force.

Blows with axes, machetes or blunt objects such as baseball bats, truncheons, etc. are often parried, resulting in typical parry injuries, or so-called nightstick fractures to the ulna. In this study, we sought to assess the impact energy required to break the ulna in such parry incidents in an experimental setting using semisynthetic and fully synthetic models. Twenty-seven sheep radii and 33 polyurethane synthetic bones were cast into gelatin prior to being fired at with missiles made of a section of an axe blade or steel rod at different firing velocities using a compressed-nitrogen cannon. Each model was then examined as to the presence of hair-line fractures or complete fractures. Sheep bones and synthetic bones displayed comparable results when struck by the axe missile; here, a clear fracture threshold was evident between 14.00 and 15.26 J. When struck by the rod missile, only the synthetic bones produced significant results, namely a fracture threshold between 20.15 and 23.59 J. In conclusion, our results show an ulnar fracture threshold of approximately 15 J when struck by an axe. The experiments regarding blows with a rod displayed a fracture threshold of around 22 J, but, as this could not be validated with biological bones, this result is questionable.

Bullet fragmentation preceding a contour shot: case study and experimental simulation.

In medico-legal literature, only a small number of publications deal with lethal injuries caused by shots with modified guns. This might lead to the conclusion that such cases are extremely rare. However, there are cases again and yet again. During the investigation process, the modified gun is of particular importance since it can show an unusual ballistic behaviour. The present paper reports on a suicide of a 60-year-old man, committed with a modified revolver and a lead bullet. The man had a single gunshot wound with entrance at the right temporal bone. Autopsy revealed that the bullet had fragmented into two major parts. The smaller one stood outside the cranial cavity and pushed its way alongside between the cranial bone and scalp to its end position in the left temporal area. The bigger part entered the cranial cavity and ended in the left parietal lobe. In shots on ballistic soap and on a head-model, the ballistics of the weapon and lead bullet were characterized. The angle necessary for bullet fragmentation was determined by shots on ballistic soap and turned out to be 55°-60° at a velocity of around 200 m/s. This knowledge was transferred to contact shots on a head-model consisting of a layered polyurethane sphere filled with 10 % ballistic gelatine and covered with a skin-like cap almost all around. The resulting injury pattern corresponded to the one of the suicide person. The bigger bullet part entered the skull while the smaller part pushed its way alongside between skin and skull causing an outer contour shot. Furthermore, the revolver was documented firing off two bullets by one trigger pull-a phenomenon of importance for forensic casework the authors have not found reported in forensic literature.

Incidence of auditory ossicle luxation and petrous bone fractures detected in post-mortem multislice computed tomography (MSCT).

As the auditory ossicles are difficult to display without harming them in conventional autopsies, lesions of these minute bones and the ossicular chain are regularly missed. In this study, the method of choice in clinical medicine for the examination of such lesions, namely multislice computed tomography, was applied to 100 corpses. The hereby obtained results regarding ossicle luxation and petrous bone fracture indicated that the lesions were not dependant on the amount, but rather on the type of energy inflicted to the head.

Correlation between skeletal trauma and energy in falls from great height detected by post-mortem multislice computed tomography (MSCT).

Fatal falls from great height are a frequently encountered setting in forensic pathology. They present--by virtue of a calculable energy transmission to the body--an ideal model for the assessment of the effects of blunt trauma to a human body. As multislice computed tomography (MSCT) has proven not only to be invaluable in clinical examinations, but also to be a viable tool in post-mortem imaging, especially in the field of osseous injuries, we performed a MSCT scan on 20 victims of falls from great height. We hereby detected fractures and their distributions were compared with the impact energy. Our study suggests a marked increase of extensive damage to different body regions at about 20 kJ and more. The thorax was most often affected, regardless of the amount of impacting energy and the primary impact site. Cranial fracture frequency displayed a biphasic distribution with regard to the impacting energy; they were more frequent in energies of less than 10, and more than 20 kJ, but rarer in the intermediate energy group, namely that of 10-20 kJ.

Gunshot injuries detected by post-mortem multislice computed tomography (MSCT): a feasibility study.

Modern cross-sectional imaging techniques are being increasingly implemented in forensic pathology. These methods may serve as an adjuvant to classic forensic autopsies or even replace them altogether in the future. In order to assess the practicability of such a method, namely post-mortem multislice computed tomography (MSCT) in fatal gunshot injuries, 22 corpses underwent such an examination prior to forensic autopsy. The cardinal questions of the location of entrance and exit wounds, the detection of bullets and bullet fragments in the body, the bullet course, inflicted injuries and cause of death were addressed at MSCT and autopsy. The results of the two techniques revealed that post-mortem MSCT can answer these questions reliably and is therefore a useful tool in the assessment of such injuries.

Effect of shortening the barrel in contact shots from rifles and shotguns.

In a suicidal gunshot fired to the chest from a carbine, the barrel of which had been shortened to half its original length, an unexpectedly large degree of destruction of the anterior thoracic wall with extensive undermining of the subcutis was found. This phenomenon was investigated for reconstructive purposes by firing test shots from two different long guns (caliber 7.92 x 57 repeating rifle with full-jacketed pointed bullet and caliber 12/70 single-barreled shotgun with shotgun slug) into blocks of soap (38 x 25 x 25 cm). The contact shots were fired before and after shortening the barrels (repeating rifle from 60 to 30 cm and single-barreled shotgun from 72 to 36 cm). The volume of the cavities in the simulant was visualized three-dimensionally with the help of a multislice computed tomography (CT) scanner and calculated sectionally. With the repeating rifle and the single-barreled shotgun, the shots from the sawed-off barrels produced significantly larger cavity diameters in the first section of the bullet track. This effect is attributable to the fact that, with a shortened barrel, the gas pressure at the muzzle is higher, thus, leading to increased expansion in the initial part of the wound track in contact shots.

Gunshot-related displacement of skin particles and bacteria from the exit region back into the bullet path.

In previous studies, it was shown that there is a gunshot-related transport of skin particles and microorganisms from the entrance region into the depth of the bullet path. The present study deals with the question of whether gunshots may also cause a retrograde transport of skin particles and microorganisms from the bullet exit region back into the bullet path. For this purpose, we used a composite model consisting of rectangular gelatin blocks and pig skin. The skin pieces were firmly attached to the gelatin blocks on the side where the bullet was to exit. Prior to the test shots, the outer surface of the pig skin was contaminated with a thin layer of a defined bacterial suspension. After drying the skin, test shots were fired from a distance of 10 m using cartridges calibre .38 spec. with different bullet types. Subsequent analyses showed that in all shots with full penetration of the composite model, the bullet path contained displaced skin particles and microorganisms from the skin surface at the exit site. These could be regularly detected in the distal 6-8 cm of the track, occasionally up to a distance of 18 cm from the exit hole. The distribution of skin particles and microorganisms is presented and the possible mechanism of this retrograde transport is discussed.

Gunshot-related transport of micro-organisms from the skin of the entrance region into the bullet path.

The skin defect of a gunshot entrance wound is caused by the retrograde and anterograde displacement of skin particles. In the present study, we investigated whether gunshots to bacterially contaminated skin are associated with the transport of micro-organisms into the bullet path. The shots were fired into composite models of pig skin and gelatin blocks. The outer surface of the skin was covered with a thin layer of a defined bacterial suspension [green fluorescent protein-labelled Escherichia coli in the preliminary test and Staphylococcus epidermidis, DSM 1798, in the main test series]. After the bacterially contaminated fluid had dried, test shots were fired from a distance of 5 and 10 m using calibre .38 Special cartridges with different bullet types (round nose, truncated cone, hollow point and flat nose). Subsequent bacteriological analyses showed that all the bullet tracks in the gelatin serving as tissue simulant contained displaced micro-organisms from the skin surface. The results are presented and discussed with reference to the transport of skin particles into the depth of the wound track.

The evaluation of a synthetic long bone structure as a substitute for human tissue in gunshot experiments.

Our goal was to compare experimental gunshot wounds in our non-biological bone model with similarly created wounds in swine bones, and evaluate the results. The design of the synthetic (polyurethane) bone was patterned after human bone structure, with a compact outer layer covering a porous inner layer. Ordnance gelatin, as substitute bone marrow, was injected into the bone's hollow core. To simulate the periostium, the bone was covered with a layer of latex. Then the bone was embedded in gelatin used to simulate surrounding soft tissue. For comparison, fresh swine bones were also embedded in gelatin, and fired upon under the same guidelines. All gunshots were high-speed filmed. In our experimental study, gunshot wounds to swine bones, and to our synthetic, non-biological bones were compared. The results (the comparison between the biological swine bones and the non-biological model bones) in regard to the following points are absolutely equal: the loss of velocity and energy after striking bone, bone fragmentation, bullet deformation, and the penetrating wound channel. Continuing studies with our synthetic bone model will bring about an even greater understanding of the mechanisms of "bullet-bone interaction". For this reason, we have extended our variety of bone models to include other skeletal structures such as skull, spine, pelvis and flat bones for further gunshot experiments.

A high-speed study of the dynamic bullet-body interactions produced by grazing gunshots with full metal jacketed and lead projectiles.

Experimenting upon a synthetic, non-biological Skull-Brain Model, our goal was to document and study the bullet-body interaction of grazing (glancing, tangential) gunshots. Thanks to the high-speed study of the dynamic bullet-body interaction it was possible to document the glancing behavior of projectiles with a resolution of 50 million pictures per second. It was possible to demonstrate the differing deformation and fragmentation patterns between the 9mm Luger full metal jacketed projectile and the 38 Smith & Wesson (S & W) lead round nose projectile. In a true-to-life manner the morphologic fracture systems could be documented by utilization of the model in dependence of the projectile's behavior, deformation, and fragmentation. Based on these experimental studies with body models, conclusions could be drawn for surgical and reconstructive forensic questions in real cases. In summary, model substitutes offer a suitable basis for the study of the bullet-body interaction because the experiments are reproducible, totally independent of the biological variances of corpse and animal experiments, and are harmless from the ethical perspective.

The dynamic development of the muzzle imprint by contact gunshot: high-speed documentation utilizing the "skin-skull-brain model".

Many contact gunshots produce a muzzle imprint in the skin of the victim. Different mechanisms have been discussed in literature as being responsible for the creation of the muzzle imprint. Experimenting upon the synthetic non biological skin-skull-brain model, our goal was to document and study the creation of the muzzle imprint with the aid of high-speed photography. In our experiments, we could document with our high-speed photography (at exposure rates in the range of nanoseconds) the bulging, the pressing against the muzzle, and the splitting of the artificial skin. Furthermore, it was possible to photographically record the back pattern of synthetic tissue particles. And, the soot and gunpowder cavity could be reproduced experimentally. In conclusion the experiments completed with the skin-skull-brain model, using high-speed photography for documentation, show the promising possibilities of experimental ballistics with body models.

The "skin-skull-brain model": a new instrument for the study of gunshot effects.

In order to create and study wound morphology, a "skin-skull-brain model" had to be designed which would make the laboratory reproduction of a real ballistic injury possible. To simulate the human skin, an artificial skin (a silicon cap) is used. This silicon scalp contains synthetic fibers (artificial leather) to simulate the collagen and fat of the scalp. The artificial skull is a layered polyurethane sphere (19 cm o.d.; and 5, 6, or 7 mm thick) constructed in a specially designed form with a Tabula externa, Tabula interna, and a porous Diploe sandwiched in between. The periostium of the artificial skull is made of latex. This elastic latex layer prevents the bone fragments from scattering after the model has been struck by gunfire. The brain itself is simulated with ordnance gelatin, 10% at 4 degrees C, a material well known in wound ballistics. Gunshots were fired at a distance of 10 m from the model. During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real gunshot injuries. Using the "skin-skull-brain model" has some significant advantages: the model is inexpensive, easy to construct, instantly available for use, and eliminates ethics conflicts. The main advantage of such a model is, in comparison with biological substances, the high reproducibility of inflicted traumas.

A study of the morphology of gunshot entrance wounds, in connection with their dynamic creation, utilizing the "skin-skull-brain model".

The goal of this study was to document the dynamic effects created within, and the developing mechanisms of a gunshot entrance wound to the skin utilizing high-speed photography and the "skin-skull-brain model". The high-speed photography was taken with an Imacon 468/Hadland-Photonics camera. Full metal jacketed, 9 mm Luger projectiles were fired at the target model from a distance of 10 m. During the evaluation of the "skin-skull-brain model", it was possible to show that injuries inflicted to this model are fully comparable to the morphology of equivalent real gunshot entrance wounds. It has been possible to document and study the dynamic process of the "bullet-skin-interaction" in the gunshot entrance wound. The development of the morphologic terms of the entrance wound are discussed. In combination with high-speed photography, this "skin-skull-brain model" is a perfect tool for the documentation and the study of the dynamic development of gunshot entrance wounds in the skin.

Body models in forensic ballistics: reconstruction of a gunshot injury to the chest by bullet fragmentation after shooting through a finger.

Forensic science uses substitutes to reconstruct injury patterns in order to answer questions regarding the dynamic formation of unusual injuries. Using a case study, an experimental simulation of a finger was designed, for the first time with a combination of hard wood and glycerin soap. With this model as an intermediate target simulation, it was possible not only to demonstrate the "bullet-body (finger) interaction", but also to recreate the wound pattern found in the victim. This case demonstrates that by using ballistic models and body-part substitutes, gunshot cases can be reproduced simply and economically, without coming into conflict with ethical guidelines.

Experimental arrow wounds: ballistics and traumatology.

OBJECTIVE: To provide information on the ballistics and the wounding potential of different arrows or bolts fired from different weapons and to investigate the suitability of simulant media for experimental arrow wounds. METHODS: A longbow, a compound bow, and a crossbow were used to fire a variety of modern and ancient arrows. Fresh corpses of four adult pigs (47 shots) and blocks of gelatin and soap (48 shots) were used as target media, and the resulting wound tracts were examined. The range of fire was 8 m and the velocity was recorded at a distance of 3 m (and 16 m in additional shots) by light screen devices. RESULTS: The mean velocities recorded ranged from 45 m/s (longbow) to 67 m/s (compound bow). The excellent exterior ballistics of arrows results in only a small initial decrease in velocity of O.10 to 0.18 m x s(-1) x m(-1). The penetration depths were reproducible for the same arrowhead fired into the same simulant medium but differed considerably when compared with those in soft tissue. In nonbone tissue, the penetration depth was substantial (17-60 cm) and depended on velocity and especially on the type of arrowhead. All arrows penetrated deeply into the large body cavities and injured organs as long as no thick bone had to be perforated. Flat bones such as ribs were always perforated. Extraction of arrowheads from thick bone proved to be difficult in some cases. The wounding mechanism was a combination of incision and puncture, which facilitated deep penetration of tissue and produced clean-cut wounds. CONCLUSION: Gelatin and soap are not suitable for experimental arrow wounds. Every arrow wound carries a lethal potential. The severity of the wound depends primarily on the target area and the type of arrowhead. Extraction of arrowheads from thick bone has to be performed carefully.

Ballistic aspects of tandem-loaded cartridges of identical caliber.

Tandem loading of a cartridge of the same caliber is possible only if the diameter of the barrel is sufficiently wide. This requirement is met by the .22 long shot Anschütz miniature clay pigeon gun. Ballistic experiments with tandem-loaded cartridges of the same caliber as those loaded in the normal way showed the bullet of the regularly loaded cartridge to impact the muzzle-loaded cartridge. On firing a shot, the bullet of the posterior cartridge penetrates the anterior one, expanding the case of the first cartridge to the diameter of the barrel and disintegrating the bullet. Regardless of whether the muzzle-loaded cartridge is ignited or not, the discharge speed of the projectiles (v0) is considerably below that of single shots. Calculations yielded a theoretical reduction by about 60%. In accordance with the formula E=1/2*m*v2, in terms of the energy released, the elevated mass of the projectile is of secondary importance compared with the reduction of v0. Although the "projectile" mass is more than twice the normal rate, the energy density is significantly reduced and the biological effect is attenuated. This also became apparent in the failed suicide attempt of a 43-year-old male who used a miniature clay pigeon gun to shoot himself in the forehead at a range of a few centimeters. He had inserted a second cartridge, base to head with the first cartridge, in the factory-bored barrel of the gun. The leading cartridge was destroyed by the regularly loaded one. The pierced and expanded case of the leading cartridge was found nearby the injured man and was at first taken to be the jacket of a larger-caliber bullet.

On the physics of momentum in ballistics: can the human body be displaced or knocked down by a small arms projectile?

Shooting incidents are often portrayed as resulting in a sometimes violent backwards displacement of the victim. This opinion is also not infrequently held by expert witnesses. The physical force responsible for this would be momentum (mass x velocity). The physics of momentum in ballistic injury is explained in detail. The maximum momentum transferred from different small arms projectiles including large calibre rifles and a 12-gauge shotgun only results in a backwards motion of a 80 kg target body of 0.01-0.18 m/s, which is negligible compared to the velocity of a pedestrian (1-2 m/s). Furthermore, counterbalance is constantly maintained by neurophysiological reflexes. So the effect of the momentum transferred from the missile is virtually zero and there is no backwards motion of the person shot. Empirical evidence verifying these calculations can be obtained from hunting big game, from human gunshot victims and from a video documentary demonstrating the lack of any backwards motion of a person wearing body armour after hits from a centre fire rifle. So the alleged backwards hurling of a person shot is nothing but a myth which should be refuted not only because it is incorrect but also because it can result in miscarriages of justice.

[Recoil-induced rifle butt mark on the ceiling in suicidal gunshot injury]. / Rückstossbedingter Gewehrkolbenabdruck an der Zimmerdecke bei suizidaler Schussverletzung.

In a suicide case the butt of the weapon (double-barrelled shotgun) produced a characteristically shaped mark at the ceiling, which could be physically explained by the recoil effect and was a clue that the victim had fired the shot himself. The ammunition used was a cartridge with a rifled shotgun slug (Brenneke type). The contact shot into the temple resulted in the rupture of the skull with exenteration of the brain. As the weapon remained lying on the body of the suicide after the shot, brownish traces of rust could form at the places of contact with steel parts.