Mock jurors' evaluation of firearm examiner testimony.

OBJECTIVES: Firearms experts traditionally have testified that a weapon leaves "unique" toolmarks, so bullets or cartridge casings can be visually examined and conclusively matched to a particular firearm. Recently, due to scientific critiques, Department of Justice policy, and judges' rulings, firearms experts have tempered their conclusions. In two experiments, we tested whether this ostensibly more cautious language has its intended effect on jurors (Experiment 1), and whether cross-examination impacts jurors' perception of firearm testimony (Experiment 2). HYPOTHESES: Four hypotheses were tested. First, jurors will accord significant weight to firearm testimony that declares a "match" compared to testimony that does not (Experiments 1 and 2). Second, variations to "match" language will not affect guilty verdicts (Experiment 1). Third, only the most cautious language ("cannot exclude the gun") would lower guilty verdicts (Experiment 1). Fourth, cross-examination will reduce guilty verdicts depending on specific language used (Experiment 2). METHOD: In two preregistered, high-powered experiments with 200 mock jurors per cell, participants recruited from Qualtrics Panels were presented with a criminal case containing firearms evidence, which varied the wording of the examiner's conclusion and whether cross-examination was present. These variations include conclusion language used by practitioners, language advised by government organizations, and language required by judges in several cases. Participants gave a verdict, rated the evidence and expert in all conditions. RESULTS: Guilty verdicts significantly increased when a match was declared compared to when a match was not declared. Variation in conclusion language did not affect guilty verdicts nor did it affect jurors' estimates of the likelihood the defendant's gun fired the bullet recovered at the crime scene. In contrast, however, a more cautious conclusion that an examiner "cannot exclude the defendant's gun" did significantly reduce guilty verdicts and likelihood estimates alike. The presence of cross-examination did not affect these findings. CONCLUSION: Apart from the most limited language ("cannot exclude the defendant's gun"), judicial intervention to limit firearms conclusion language is not likely to produce its intended effect. Moreover, cross-examination does not appear to affect perceptions or individual juror verdicts. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The role of the gunshot residue expert in case review - A case study.

This paper details the review of the gunshot residue (GSR) evidence relating to a 2002 murder involving the discharge of a pistol where the Prosecution used the GSR findings together with voice identification evidence and obtained a conviction in the case of R v Dwaine George. Mr George was subsequently represented by Cardiff University Law School's Innocence Project who made representations to the Criminal Cases Review Commission (CCRC) based on issues relating to the GSR evidence. The CCRC commissioned their own expert review and based on these findings referred the conviction to the Court of Appeal stating that in their opinion the weight of the GSR evidence was not appropriately conveyed to the jury at the original Trial and there should have been a warning relating to the limited significance that could be attached to the evidence. The Court of Appeal concluded that had the jury been aware of the full extent of the potential alternative sources of GSR in the case and the limited number of particles found on a jacket related to Mr George then this would have affected the decision of the Trial jury. The appeal was allowed and the convictions were quashed.

Fractura de radio por proyectil que permite reproducir la posición de la víctima / Fracture of radius by projectile allowing to reproduce the position of the victim

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Significance of Crime Scene Visit by Forensic Pathologist in Cases of Atypical Firearm Injuries.

Deaths due to firearms are some of the interesting and contentious cases that a forensic pathologist/autopsy surgeon encounters in his practice. Whenever there is 'ambiguity' regarding the nature or sequence of events any unnatural deaths including those caused by firearms the practice of visiting crime scene should be encouraged especially in a country like India where autopsy surgeons often neglect it. Here we present a case report in which there were inconsistencies in the autopsy findings with the alleged history. The witnesses heard about four to six gunshot sounds, whereas only two spent cartridge cases were retrieved from the crime scene. Authors identified the atypical nature of firearm injuries sustained by the victims that were possible by just two bullets. Crime scene visit was undertaken where we discovered the possibility of the echo effect behind the production of four to six sounds. Further by using computer software program, positions of the gunman, victims and the bullet trajectory of the two bullets was created.

Ballistic parameters and trauma potential of carbon dioxide-actuated arrow pistols.

Medical literature abounds with reports of injuries and fatalities caused by arrows and crossbow bolts. Crossbows are of particular forensic and traumatological interest, because their mode of construction allows for temporary mechanical storage of energy. A newly developed type of pistol (Arcus Arrowstar), which belongs to the category of air and carbon dioxide weapons, discharges arrow-shaped bolts actuated by carbon dioxide cylinders. As, to the best of the authors' knowledge, literature contains no information on this uncommon subclass of weapons it is the aim of this work to provide the experimental data and to assess the trauma potential of these projectiles based on the ascertained physical parameters. Basic kinetic parameters of these carbon dioxide-actuated bolts (velocity v = 39 m/s, energy E = 7.2 J, energy density E' = 0.26 J/mm(2)) are similar to bolts discharged by pistol crossbows. Subsequent firing resulted in a continuous and fast decrease in kinetic energy of the arrows. Test shots into ballistic soap blocks reveal a high penetration capacity, especially when compared to conventional projectiles of equal kinetic energy values (like, e.g., airgun pellets). To conclude, these data demonstrate the high efficiency of arrow-shaped projectiles, which are also characterized by a high cross-sectional density (ratio of mass to cross-sectional area of a projectile).

[The surgically treated gunshot injury. Securing evidence in hospitals without primary participation of police or legal medicine]. / Die operierte Schussverletzung. Schussspurensicherung im klinischen Bereich ohne primäre Beteiligung der Polizei oder der Rechtsmedizin.

Against the background of a problematic reconstruction of a hunting accident, the question arises how such cases can be handled in hospitals and how exhibits can be adequately dealt with. After evaluating a questionnaire on current conditions of securing evidence in cases of surgically treated gunshot wounds from 26 surgical institutions in Mecklenburg-Western Pomerania and in consideration of the certified advanced training in the field of legal medicine, recommendations are given regarding the securing of evidence within the clinical setting without primary involvement of police or legal medicine.

Development of a skull/brain model for military wound ballistics studies.

Reports on penetrating ballistic head injuries in the literature are dominated by case studies of suicides; the penetrating ammunition usually being .22 rimfire or shotgun. The dominating cause of injuries in modern warfare is fragmentation and hence, this is the primary threat that military helmets protect the brain from. When helmets are perforated, this is usually by bullets. In combat, 20% of penetrating injuries occur to the head and its wounding accounts for 50% of combat deaths. A number of head simulants are described in the academic literature, in ballistic test methods for helmets (including measurement of behind helmet blunt trauma, BHBT) and in the 'open' and 'closed' government literature of several nations. The majority of these models are not anatomically correct and are not assessed with high-velocity rifle ammunition. In this article, an anatomically correct 'skull' (manufactured from polyurethane) and 'brain' (manufactured from 10%, by mass, gelatine) model for use in military wound ballistic studies is described. Filling the cranium completely with gelatine resulted in a similar 'skull' fracture pattern as an anatomically correct 'brain' combined with a representation of cerebrospinal fluid. In particular, posterior cranial fossa and occipital fractures and brain ejection were observed. This pattern of injury compared favourably to reported case studies of actual incidents in the literature.

[The determination of the ballistics of a hunting rifle loaded with a Poleva-3 bullet].

Various approaches are considered to determine the shooting range of a hunting rifle loaded with a Poleva-3 bullet from the specific features of gunshot injuries inflicted by container-type Poleba-3 bullets for hunting rifles.

["Piggyback" shot: ballistic parameters of two simultaneously discharged airgun pellets]. / Der "Huckepack"-Schuss: ballistische Parameter doppelt geladener Luftgewehr-Projektile.

Green and Good reported an uncommon case of homicide committed with an air rifle in 1982 (Am. J. Forensic Med. Pathol. 3: 361-365). The fatal wound was unusual in that two airgun pellets were loaded in so-called "piggyback" fashion into a single shot air rifle. Lack of further information on the ballistic characteristics of two airgun pellets as opposed to one conventionally loaded projectile led to this investigation. The mean kinetic energy (E) of the two pellets discharged in "piggyback" fashion was E = 3.6 J and E = 3.4 J, respectively. In comparison, average kinetic energy values of E = 12.5 J were calculated for conventionally discharged single diabolo pellets. Test shots into ballistic soap confirmed the findings of a single entrance wound as reported by Green and Good. While the ballistic background of pellets discharged in "piggyback" fashion could be clarified, the reason behind this mode of shooting remains unclear.

Subcaliber discarding sabot airgun projectiles.

Medical literature abounds with reports on injuries and fatalities caused by airgun projectiles. While round balls or diabolo pellets have been the standard projectiles for airguns for decades, today, there are a large number of different airgun projectiles available. A very uncommon--and until now unique--discarding sabot airgun projectile (Sussex Sabo Bullet) was introduced into the market in the 1980s. The projectile, available in 0.177 (4.5 mm) and 0.22 (5.5 mm) caliber, consists of a plastic sabot cup surrounding a subcaliber copper-coated lead projectile in typical bullet shape. Following the typical principle of a discarding sabot projectile, the lightweight sabot is supposed to quickly loose velocity and to fall to the ground downrange while the bullet continues on target. These sabot-loaded projectiles are of special forensic interest due to their non-traceability and ballistic parameters. Therefore, it is the aim of this work to investigate the ballistic performance of these sabot airgun projectiles by high-speed video analyses and by measurement of the kinetic parameters of the projectile parts by a transient recording system as well as observing their physical features after being fired. While the sabot principle worked properly in high-energy airguns (E > 17 J), separation of the core projectile from the sabot cup was also observed when discharged in low-energy airguns (E < 7.5 J). While the velocity of the discarded Sussex Sabo core projectile was very close to the velocity of a diabolo-type reference projectile (RWS Meisterkugel), energy density was up to 60 % higher. To conclude, this work is the first study to demonstrate the regular function of this uncommon type of airgun projectile.

[Forensic aspects of gunshot suicides in Germany]. / Gerichtsmedizinische Aspekte suizidaler Schussverletzungen--eine Übersichtsarbeit am Beispiel Deutschlands.

Suicidal gunshot wounds are a common appearance in forensic casework. The main task of the coroner lies in the detection of typical pathomorphological correlates, thus differentiating between homicide, suicide and accident. Apart from characteristic bloodstain patterns on the gun and shooting hand, the localisation of the entrance wound and the position of the weapon, additional details such as family background or medical history are important aspects of forensic investigation. An uncommon choice of weaponry and its unusual morphological manifestation often complicate the examination and reconstruction of such cases. Furthermore, due to social stigmatisation, the possibility of secondary changes by relatives at the crime scene should be considered. In addition to autopsy findings, a careful crime scene investigation and bloodstain pattern analysis, a ballistic reconstruction can be an essential tool to gain knowledge of the shooting distance and position of the gun.

[The reconstruction of gunshot circumstances by means of situational forensic medical expertise].

The authors discuss the objective potential of situational forensic medical expertise for the determination of the direction and the distance of a gunshot as well as the position of the gun in the shooter's hand. The use of fundamental theoretical propositions determining the essence of the form of expertise being considered is illustrated by an example from forensic medical practice.

The effect of firearm muzzle gases on the backspatter of blood.

Injuries caused by gunshots can produce what bloodstain pattern analysts know as "backspatter." Observations about the presence or absence of backspatter on an individual may be used in court as evidence of guilt or innocence. The discharge of three firearms (.22 caliber revolver, .38 caliber revolver, and .308 caliber rifle) and the resulting impact of bullets on a blood source were recorded using high-speed digital video imaging. Blood droplets, firearm muzzle gases, and ballistic shock waves were visualized using standard reflected light and shadowgraphy imaging techniques. A significant interaction between air currents, muzzle gases, and particulate material emanating from the firearms upon discharge with backspattered blood was observed. Blood droplets, initially spattered back toward the firearm and the shooter, were observed to change direction under the influence of firearm-induced air currents and were blown forward toward and beyond their original source location. Implications for experts testifying in court and for bloodstain pattern instructors are discussed.

[Traumatic potential of colour marking cartridges (FX ammunition)]. / Verletzungspotential von FX-Farbmarkierungsmunition.

Colour marking cartridges as the FX ammunition (Simunition Europe, Brussels) are increasingly used by the police for realistic close range combat training. Conversion kits for service weapons of different manufacturers are available. The ballistic data of this ammunition is reported and experimentally verified. The risk of injury seems to be very low, if the recommended protective equipment is used. Small hematomas up to superficial lacerations are to be expected only in areas over a bony support. Shots to the unprotected eye will result in severe injuries.

[Medicolegal aspects of witnessed suicide due to gunshot to the head. II. Legal medicine aspects and examination of the firing hand]. / Rechtsmedizinische Aspekte des Suizides durch Kopfschuss vor Zeugen. Teil II: Rechtsmedizinische Befunde und Schusshanduntersuchung.

The second part of the paper on suicides by gunshots to the head in the presence of witnesses focuses on relevant morphological autopsy findings such as entrance site, signs of close range or contact shots, bullet path etc. and also discusses selected aspects of ascertaining gunshot residues. For the identification of the shooter an integral medicolegal assessment of all the facts including the investigation results and the autopsy findings is essential. However, the morphological findings alone do not allow safe diagnosis, as for example in a homicide the temporal region, which was affected in all our cases, may have been deliberately chosen by the perpetrator as a localization typical of suicide. Thus methods to ascertain gunshot residues on the firing hand (by means of adhesive films and the polyvinyl-alcohol collection method--PVAL) are of great practical importance. In seven cases adhesive films and/or the polyvinyl-alcohol collection method were used. In one case the gunshot residues (GSR) were analysed by means of tape lifts and subsequent scanning electron microscopy (SEM). It was found that especially the combined application of topographical (adhesive tape/PVAL) and cumulative (SEM) methods allowed for the doubtless identification of the shooter, thus usually confirming the suicide. By the example of one case it is demonstrated that without the immediate collection of evidence at the scene objective reconstruction of the event becomes impossible. On the basis of the reported cases recommendations are finally given for a differentiated approach in the medicolegal evaluation of alleged witnessed suicide by gunshot (to the head).