Image analysis of gunshot residue on entry wounds. II--A statistical estimation of firing range.

A statistical investigation of the relationship between firing range and the amount and distribution of gunshot residue (GSR), used automated image analysis (IA) to quantify GSR deposit resulting from firings into pig skin, from distances ranging between contact and 45 cm. Overall, for a Ruger .22 semi-automatic rifle using CCI solid point, high velocity ammunition, the total area of GSR deposit on the skin sections decreased in a non-linear fashion with firing range. More specifically there were significant differences in the amount of GSR deposited from shots fired at contact compared with shots fired from distances between 2.5 and 45 cm; and between shots fired from a distance of 20 cm or less, with shots fired at a distance of 30 cm or more. In addition, GSR particles were heavily concentrated in the wound tract only for contact and close range shots at 2.5 cm, while the particle distribution was more uniform between the wound tract and the skin surfaces for shots fired from distances greater than 2.5 cm. Consequently, for future scientific investigations of gunshot fatalities, once standards have been established for the weapon and ammunition type in question, image analysis quantification of GSR deposited in and around the gunshot wound may be capable of providing a reliable, statistical basis for estimating firing range.     

Image analysis of gunshot residue on entry wounds: II – A statistical estimation of firing range

A statistical investigation of the relationship between firing range and the amount and distribution of gunshot residue (GSR), used automated image analysis (IA) to quantify GSR deposit resulting from firings into pig skin, from distances ranging between contact and 45 cm. Overall, for a Ruger .22 semi-automatic rifle using CCI solid point, high velocity ammunition, the total area of GSR deposit on the skin sections decreased in a non-linear fashion with firing range. More specifically there were significant differences in the amount of GSR deposited from shots fired at contact compared with shots fired from distances between 2.5 and 45 cm; and between shots fired from a distance of 20 cm or less, with shots fired at a distance of 30 cm or more. In addition, GSR particles were heavily concentrated in the wound tract only for contact and close range shots at 2.5 cm, while the particle distribution was more uniform between the wound tract and the skin surfaces for shots fired from distances greater than 2.5 cm. Consequently, for future scientific investigations of gunshot fatalities, once standards have been established for the weapon and ammunition type in question, image analysis quantification of GSR deposited in and around the gunshot wound may be capable of providing a reliable, statistical basis for estimating firing range.     

Morphological characteristics of gunshot wounds of liver and spleen

Stellate wounds are to be expected in gunshot injuries to the liver and spleen. As to their configuration, they resemble the skin breaks in an absolute close-range shot. The exit wound is larger than the entry wound. The genesis and utility of such injuries for reconstruction of the shot direction are discussed with reference to seven gunshot mortalities. Stellate wounds could also be achieved by shooting at isolated cadaver organs. The experimentally produced gunshot wounds differed from those produced in vivo in that the entry and exit wounds were equally large.     

Confusing injury findings in a suicidal gunshot fired to the chest from a carbine with a sawed-off barrel

The stellate bullet entrance wound is one of the facultative features of a contact shot. For the formation of a star-shaped wound two factors are of special importance: first, an extensive bony support underlying the skin in the entrance region, and second, a strong propellant charge of the cartridge fired. Contact shots to the precordial region usually do not cause stellate entrance wounds, even if high-powered rifle ammunition is used. In the reported case, an injury pattern was observed that was not in line with normal findings and seemed confusing at first. Following a suicidal gunshot to the chest from a sawed-off carbine 98a (cal. 8 x 57 Js), a 4.5 cm wide, gaping bullet entrance wound with radiating tears was found. Instead of the usual pocket, the anterior thoracic wall showed a fist-sized area of destruction with extensive undermining of the subcutis. Not far from the entrance hole, a rib fragment had become displaced retrogradely thus perforating the skin from the inside out. The unusual pattern of findings could be explained by the fact that the barrel had been sawed off: as a result of this manipulation, a considerable part of the propellant charge had been converted outside the barrel, i.e. in the initial section of the bullet path.     

The hydrodynamic effect of gunshots in cranial explosive shots

Case report on five fatal gunshot injuries in which discharge of the cranial contents had occurred owing to a skull blast. Despite an appreciable explosive action with destruction of the bony cranium, the brains were not completely destroyed. In analogy to the "Kr?nlein shot", comparative reflections were made concerning wound ballistics. The case reports show that injury patterns resembling "Kr?nlein shot" may arise in cranial blast shots in rare cases despite destroyed projectile parts and even in a mouth shot.     

Gunshot residue patterns on skin in angled contact and near contact gunshot wounds

The goal of this study was the reproduction of shape and pattern of gunshot residues in near contact and contact gunshot wounds by a series of experimental gunshots on a skin and soft tissue model. The aim was to investigate the shape and direction of soot deposits with regard to the muzzle according to different muzzle-target angles, firing distances, type of ammunition and weapon and barrel length. Based on a review of the literature and on the results of the experiments the authors could make the following statements of gunshot residues in angled contact and close contact gunshot: (1) gunshot residues on the target surface can be differentiated in a "inner" and "outer powder soot zone"; (2) the outer powder soot zone is much less visible than the inner powder soot zone and may lack on human skin; (3) with increasing muzzle target distance both inner and outer powder soot halo increase in size and decrease in density; (4) in angled shots the inner powder soot halo shows an eccentric, elliptic shape which points towards the muzzle, regardless of ammunition, calibre and barrel length; (5) the outer powder soot points away from the muzzle in angled contact and close contact shots.     

Forensic medical expert evaluation of gunshot injuries of brain skull

Forensic medical experts are offered a set of morphological signs which help identify the gunshot origin of a skull injury, identify which of the injuries is the inlet and which is the outlet, specify the direction of the shot and succession of formation of injuries in cases with several shots. The author suggests evaluating a gunshot wound in the head with due consideration for the mechanisms of its formation. From a complex of signs of a gunshot injury to the brain skull he singles out the tissue defect with a conical channel and the edge of bone defect, additional injury to the external compact plate near the inlet, and type, number, and location of the radial and concentric cracks. Analysis of the morphology of the above listed signs of gunshot injuries to the skull notable extends the potentialities of forensic medical expert evaluation in cases with gunshot injuries.     

Image analysis of gunshot residue on entry wounds. I--The technique and preliminary study.

An automated image analysis (IA) technique has been developed to obtain a measure of the amount (i.e. number and area) of gunshot residue (GSR) particles within and around a gunshot wound. Sample preparation and IA procedures were standardised to improve the reproducibility of the IA measurements of GSR. Measurements of GSR from test firings into goat hide were enhanced by staining the barium and lead components present on the skin sections with Alizarin Red S. The amount of GSR detected on the stained skin sections was compared with backscatter electron micrographs of the same sections. The differences were deemed to be insignificant when the variability in the repeated test firings were taken into consideration. Preliminary results indicated that the decreasing relationship between firing range and the amount of GSR deposited was non-linear, and that for firing ranges of up to 20 cm the amount of GSR deposited from repeated shots fired from the same distance was highly variable.     

Frequency of bone lesions: an inadequate criterion for gunshot wound diagnosis in skeletal remains

A retrospective study was carried out on 130 fatalities due to gunshot wounds to determine whether the combined absence of bone damage and projectile in a skeleton is sufficient to eliminate a diagnosis of gunshot wound. Our findings showed that bone lesions were present in about 90% of the cases and were associated with intracorporeal projectile(s) in about 70% of the cases. The presence or absence of bone lesions seemed independent of the gun characteristics, the shot conditions, and the type of death. The cause of death was predominantly brain injury in cases with bone lesions whereas thoracic, abdominal, and peripheral vascular causes were more frequently encountered in cases without bone damage. We concluded that the combined absence of bone lesions and intracorporeal projectile (about 5% in our series) cannot exclude a diagnosis of death secondary to gunshot wounds.     

Image analysis of gunshot residue on entry wounds: I – The technique and preliminary study

An automated image analysis (IA) technique has been developed to obtain a measure of the amount (i.e. number and area) of gunshot residue (GSR) particles within and around a gunshot wound. Sample preparation and IA procedures were standardised to improve the reproducibility of the IA measurements of GSR. Measurements of GSR from test firings into goat hide were enhanced by staining the barium and lead components present on the skin sections with Alizarin Red S. The amount of GSR detected on the stained skin sections was compared with backscatter electron micrographs of the same sections. The differences were deemed to be insignificant when the variability in the repeated test firings were taken into consideration. Preliminary results indicated that the decreasing relationship between firing range and the amount of GSR deposited was non-linear, and that for firing ranges of up to 20 cm the amount of GSR deposited from repeated shots fired from the same distance was highly variable.     

Unusual wound morphology after textile penetration by the automatic rifle (StG) 58. A case report

Technical characteristics of the used fire-arm and ammunition, the firing range and the shot through garments of the victim are essential factors, that exercise an influence on the appearance of gunshot injuries. An exemplary case-report shall emphasize the importance of these factors. It deals with a suicidal double-shot fired from an automatic rifle by a young soldier. The wounds were localized in the left chest region and the adjacent skin was blackened by soot in a remarkable geometrical pattern, although an ammunition with a smokeless charge has been used. By means of comparative shots we have good reasons to suppose this phenomenon to be caused by rests of gun powder and pressure of the explosion gas leaved in the barrel after the first shot. The second projectile pushed out this explosion gas to the skin that had been uncovered in a star-shaped way by the first shot.     

Gunshot injury caused by a training bullet]

In the course of a scuffle a 50-year old man has been shot by a revolver. The culprit and witnesses state, there has been only one shot, whereas the victim declared having been shot twice. The medico-legal investigation revealed a gunshot wound that passed through the left thigh, a grazing shot of the right hand and a superficial lesion of the skin at the forehead with sprinkled gunshot residue in the epidermis. The investigation confirmed the statement of the victim: the first shot to the forehead was caused by a plastic training cartridge, the second to the right hand and thigh by a cartridge loaded with an ordinary bullet.     

Suicide with multiple graze shots

A 77-year-old man was found in his flat with a shot to the right temple. In spite of hospital treatment he died from the head injury the next day. The weapon at the scene used for committing the suicide was a pistol, make Kaba Special (calibre 6.35 mm). At autopsy, the right temporal region showed a surgically treated, originally stellate gunshot entrance wound with a powder cavity. Close to this penetrating gunshot wound there were 3 parallel graze shot injuries of the scalp. The autopsy findings were consistent with the assumption that all the shots had been fired by the victim himself with suicidal intent. The injury pattern is presented and discussed in relation to the results of the technical investigation of the weapon and the findings at the scene.     

Mandibular fracture caused by absolute close-range gunshot with a blank cartridge fright weapon]

Bony injuries caused by starter's pistols were repeatedly observed in the form of fractures of the temporal squama and other thin osseous lamellae; in experiments rib fractures could also be produced. In the presented case a contact shot from a blank cartridge pistol caused a fracture of the lower jaw (transverse fracture with a bone fragment split off in reg. 46). The friend of the 17-year-old victim had fired a shot to the right mandibular region during an argument. In the depth of the gunshot entrance wound, which communicated with the oral cavity, intense soot deposits were found as signs of the contact shot.     

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.     

The morphology of the gunshot entry wound

The main signs of inlet gunshot wound inflicted from non-close shot distance are the following: central defect of the tissue, presence of abrasion and rub zones along the margins. During experimental study high variability of these signs was stated and new morphologic characteristics of inlet gunshot wound were detected.     

Investigating the effect of changing ammunition on the composition of organic additives in gunshot residue (OGSR)

The measurement of the organic additives in smokeless gunpowder is an attractive approach for the detection of handgun use because it provides compositional information that can help associate residues and unfired gunpowder. We investigate several factors that will be required to advance the characterization of organic gunshot residue (OGSR) as a useful forensic tool, including evaluating residue contamination from previously fired ammunition, particle-to-particle compositional variability, and compositional features resulting from the type of firing primer used. Using ammunition loaded with known smokeless powders containing different stabilizers, a sequence of shots was fired from a .357 magnum revolver, and the muzzle exit residues were collected. Compositional analysis of the residues, both in bulk and as single particles, showed only a trace of the previously fired powder in the first shot and none in subsequent shots. In an additional experiment testing conventional leaded and the new lead-free firing primers, the OGSR composition was found not to depend on the primer type.     

Frequency of blood spatters on the shooting hand and of conjunctival petechiae following suicidal gunshots wounds to the head

A total of 103 suicidal and 29 homicidal gunshot fatalities were evaluated. In 42% of the suicides, characteristic findings like blood spatters and/or powder soilings, could be found on the shooting hand by naked-eye inspection indicating the importance of an accurate examination of the deceased's hands at autopsy for a preliminary diagnosis. Petechial hemorrhages of the conjunctivae due to the gas pressure after discharge of the weapon were observed in 22% of those cases with contact shot wounds to the head/neck, but not in cases of distant shot injuries following the use of non-high velocity ammunition. Therefore, conjunctival petechiae can be regarded as an additional but optional sign of contact head shots in cases without alterations possibly influencing the development of conjunctival pin-point bleedings. The evidence of such findings can be of practical importance if the entrance shot wound cannot be examined for whatever reason.