Beat P. Kneubuehl

Wound Ballistics and the Scientific Background

Introduction. Physical Basics of Wound Ballistics. Preliminary Remarks. Frames of Reference and Systems of Units, Notation. Mechanics. Kinematics. Mass, linear momentum, force. Work and energy. Circular motion. The laws of conservation. Equations of motion. Fluid Dynamics. General. Thermodynamic principles. Material properties. Inviscid flows. Viscid flows. Jets. Measurement Techniques. General. Dynamic processes. Physical quantities. Measurement technique to detect the development of rapidly changing pressures. Historical Background and International Treaties. The Development of Small Arms. General. The development of ammunition. The development of small arms. The twentieth century. International treaties. Early Developments in Wound Ballistics. Ammunition and Arms, Ballistics. General. Ammunition. The different parts of a cartridge. Ammunition. Recent developments of ammunition. Firearms. Composition and classification of firearms. Hand guns. Rifles. Ballistics. General. Interior ballistics. Processes at the muzzle. Exterior ballistics. Stability and tractability. General Wound Ballistics. General. Preliminary remarks. What does a human being die of after being hit? Possible causes of death. Definition of various energy quantities, their derivation and relationship. Processes in the Shooting Channel (Especially the Temporary Cavity). General. Behaviour of projectiles in a dense medium. Phenomenology of the temporary cavity. Quantitative description of the temporary cavity. Instability of a projectile in a dense medium and the consequences on the temporary cavity. Sectional density influence on the shape of the temporary cavity. The behaviour of different projectiles designs in a target medium. On the sterility of projectiles. Tissue Simulants. General. Gelatine. Soap. Comparison: soap-gelatine. Tissue simulant for bones. Other Simulation Methods. Corpses. Experiments on animals. Mathematical models, computer models. Cell cultures. Wound Ballistics of Handgun Ammunition. Penetration Depth and Perforation Capacity of Projectiles in Gelatine, Soap, Muscle Tissue and Bones. General theory. Penetration depth in gelatine, soap and muscle tissue. Penetration capacity in bones. Threshold velocities of the eye. On the Effectiveness of Projectiles. General. Criteria of effectiveness. Measured values for energy release of projectiles in gelatine. Is it possible to establish a general criterion of the effect? Special Projectiles. General. Non-penetrating projectiles. Projectiles with Extraordinary ballistics qualities. Fluid jets and gas jets as projectiles. Wound Ballistics of Rifle Ammunition. General. Remote Effects. General. Shock waves. Pressure waves in blood vessels. Bone fractures in the vicinity of the shooting channel. Debridement. General. The relationship between the size of the temporary cavity and the amount of devitalized tissue. Determination of the Effectiveness of Rifle Bullets and Fragments - Casualty Criterion. General. Casualty criterion. Bases for the Formulation of Future International Treaties. Disadvantages in the wording of existing treaties. Methods of judgement independent of the type of projectile. Possibilities of standardization. Tables. Index of Tables Previously Presented in this Book. Conversion Tables. Lengths. Velocity. Mass units. Force. Pressure. Energy and work. Temperature. Material Properties. Fluids and fluidal substances. Solid substances. Caliber Designations. Caliber designation metric units. Caliber designation US units. Ballistics Data of Ammunition. Ballistics data metric units. Ballistics data US units. Projectile Designations. Projectile shape. Projectile material. Projectile construction. Geometrical Data of Some Particular Projectiles. Military projectiles. Additional projectiles. Twists Lengths, Twist Angles and Number of Revolutions.Pistols and revolvers. Rifles. Firing Tables. Pistols and revolvers. Rifles. Signal and illumination ammunition. Shotgun Calibers and Shot Pellets. Calibers of shot barrels. Ballistics properties of shot pellets. Designation of buck shot sizes. Designation of normal shot sizes (Anglo-American system). Designation of normal shot sizes (metric system). Glossary. English-German-French. German-English-French. French-German-English. Literature. Bibliography. References. Illustration References. Index.

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.

3D bloodstain pattern analysis: ballistic reconstruction of the trajectories of blood drops and determination of the centres of origin of the bloodstains

For crime scene investigation in cases of homicide, the pattern of bloodstains at the incident site is of critical importance. The morphology of the bloodstain pattern serves to determine the approximate blood source locations, the minimum number of blows and the positioning of the victim. In the present work, the benefits of the three-dimensional bloodstain pattern analysis, including the ballistic approximation of the trajectories of the blood drops, will be demonstrated using two illustrative cases. The crime scenes were documented in 3D, using the non-contact methods digital photogrammetry, tachymetry and laser scanning. Accurate, true-to-scale 3D models of the crime scenes, including the bloodstain pattern and the traces, were created. For the determination of the areas of origin of the bloodstain pattern, the trajectories of up to 200 well-defined bloodstains were analysed in CAD and photogrammetry software. The ballistic determination of the trajectories was performed using ballistics software. The advantages of this method are the short preparation time on site, the non-contact measurement of the bloodstains and the high accuracy of the bloodstain analysis. It should be expected that this method delivers accurate results regarding the number and position of the areas of origin of bloodstains, in particular the vertical component is determined more precisely than using conventional methods. In both cases relevant forensic conclusions regarding the course of events were enabled by the ballistic bloodstain pattern analysis.

Gunshot energy transfer profile in ballistic gelatine, determined with computed tomography using the total crack length method

By measuring the total crack lengths (TCL) along a gunshot wound channel simulated in ordnance gelatine, one can calculate the energy transferred by a projectile to the surrounding tissue along its course. Visual quantitative TCL analysis of cut slices in ordnance gelatine blocks is unreliable due to the poor visibility of cracks and the likely introduction of secondary cracks resulting from slicing. Furthermore, gelatine TCL patterns are difficult to preserve because of the deterioration of the internal structures of gelatine with age and the tendency of gelatine to decompose. By contrast, using computed tomography (CT) software for TCL analysis in gelatine, cracks on 1-cm thick slices can be easily detected, measured and preserved. In this, experiment CT TCL analyses were applied to gunshots fired into gelatine blocks by three different ammunition types (9-mm Luger full metal jacket, .44 Remington Magnum semi-jacketed hollow point and 7.62 × 51 RWS Cone-Point). The resulting TCL curves reflected the three projectiles’ capacity to transfer energy to the surrounding tissue very accurately and showed clearly the typical energy transfer differences. We believe that CT is a useful tool in evaluating gunshot wound profiles using the TCL method and is indeed superior to conventional methods applying physical slicing of the gelatine.

Blood-spatter patterns: Hands hold clues for the forensic reconstruction of the sequence of events

Biologic and nonbiologic traces on the hands are of particular importance for the forensic reconstruction of shooting incidents; gunpowder residue analysis in particular helps determine whether the gunshot is close range or distant. In crime scene investigation, knowledge about the morphology of bloodstain patterns–including gunshot-related back spatter–has increased since various experimental examinations have been performed in the last years; nowadays, these traces are frequently used for forensic crime scene reconstruction.The goal of this study was to deduce the position and orientation of the hands, and therefore the firearm, according to the bloodstain patterns on the hands of the deceased. For this purpose blood-spatter stains on the hands were examined on site in 5 suicides caused by gunshot. In all cases, forensically relevant conclusions regarding forensic reconstruction were enabled through close examination of the spatter marks. Therefore, in shooting incidents, analysis and documentation of blood-spatter findings on the hands is recommended before hands are tested for gunpowder residue or wrapped for the transport of the body.

Secondary skull fractures in head wounds inflicted by captive bolt guns: autopsy findings and experimental simulation

Apart from one article published by Rabl and Sigrist in 1992 (Rechtsmedizin 2:156–158), there are no further reports on secondary skull fractures in shots from captive bolt guns. Up to now, the pertinent literature places particular emphasis on the absence of indirect lesions away from the impact point, when dealing with the wounding capacity of slaughterer’s guns. The recent observation of two suicidal head injuries accompanied by skull fractures far away from the bolt’s path gave occasion to experimental studies using simulants (glycerin soap, balls from gelatin) and skull–brain models. As far as ballistic soap was concerned, the dimensions of the bolt’s channel were assessed by multi-slice computed tomography before cutting the blocks open. The test shots to gelatin balls and to skull–brain models were documented by means of a high-speed motion camera. As expected, the typical temporary cavity effect of bullets fired from conventional guns could not be observed when captive bolt stunners were discharged. Nevertheless, the visualized transfer of kinetic energy justifies the assumption that the secondary fractures seen in thin parts of the skull were caused by a hydraulic burst effect.

Determination of ethyl glucuronide and ethyl sulfate from dried blood spots

BackgroundEthyl glucuronide (EtG) and ethyl sulfate (EtS) are non-oxidative minor metabolites of ethanol. They are detectable in various body fluids shortly after initial consumption of ethanol and have a longer detection time frame than the parent compound. They are regarded highly sensitive and specific markers of recent alcohol uptake. This study evaluates the determination of EtG and EtS from dried blood spots (DBS), a simple and cost-effective sampling method that would shorten the time gap between offense and blood sampling and lead to a better reflectance of the actual impairment.MethodsFor method validation, EtG and EtS standard and quality control samples were prepared in fresh human heparinized blood and spotted on DBS cards, then extracted and measured by an LC-ESI-MS/MS method. Additionally, 76 heparinized blood samples from traffic offense cases were analyzed for EtG and EtS as whole blood and as DBS specimens. The results from these measurements were then compared by calculating the respective mean values, by a matched-paired t test, by a Wilcoxon test, and by Bland–Altman and Mountain plots.Results and discussionCalibrations for EtG and EtS in DBS were linear over the studied calibration range. The precision and accuracy of the method met the requirements of the validation guidelines that were employed in the study. The stability of the biomarkers stored as DBS was demonstrated under different storage conditions. The t test showed no significant difference between whole blood and DBS in the determination of EtG and EtS. In addition, the Bland–Altman analysis and Mountain plot confirmed that the concentration differences that were measured in DBS specimens were not relevant.

GSR deposition along the bullet path in contact shots to composite models

In contact shots, all the materials emerging from the muzzle (combustion gases, soot, powder grains, and metals from the primer) will be driven into the depth of the entrance wound and the following sections of the bullet track. The so-called “pocket” (“powder cavity”) under the skin containing soot and gunpowder particles is regarded as a significant indicator of a contact entrance wound since one would expect that the quantity of GSR deposited along the bullets path rapidly declines towards the exit hole. Nevertheless, experience has shown that soot, powder particles, and carboxyhemoglobin may be found not only in the initial part of the wound channel, but also far away from the entrance and even at the exit. In order to investigate the propagation of GSRs under standardized conditions, contact test shots were fired against composite models of pig skin and 25-cm-long gelatin blocks using 9-mm Luger pistol cartridges with two different primers (Sinoxid® and Sintox®). Subsequently, 1-cm-thick layers of the gelatin blocks were examined as to their primer element contents (lead, barium, and antimony as discharge residues of Sinoxid® as well as zinc and titanium from Sintox®) by means of X-ray fluorescence spectroscopy. As expected, the highest element concentrations were found in the initial parts of the bullet tracks, but also the distal sections contained detectable amounts of the respective primer elements. The same was true for amorphous soot and unburned/partly burned powder particles, which could be demonstrated even at the exit site. With the help of a high-speed motion camera it was shown that for a short time the temporary cavitation extends from the entrance to the exit thus facilitating the unlimited spread of discharge residues along the whole bullet path.

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.

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 projectiles 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.