New alginate-gelatine method for casting of staining inside firearm barrels.

Contact shots to the head often leave behind biological traces inside firearm barrels, a phenomenon of great forensic interest. Until now, the visualization and preservation of these traces presented a significant challenge, lacking a reliable method. This study addresses this gap by searching for a suitable method to extract the traces within a casting. Using alginate or gelatine as suitable materials, the results were hampered by serious adhesion issues and their extraction out of the firearm barrel was impeded. Finally, the combination of 11% gelatine with 1% alginate, introduced into the barrel around a 'central spine', succeeded to consistently produce replicable castings. Experimental contact shots displayed a distinct staining gradient from the muzzle to the rear of the barrel, as revealed through endoscopy and proved in the macroscopic casting. The technique proved effective for various common handgun barrels and successfully preserved blood and gunshot residue (GSR) patterns within the barrel. This method offers the dual benefits of visually mapping staining patterns and securing localized samples for targeted molecular genetic analysis in forensic investigations.

The muzzle to target distance -staining inside different parts of the firearm barrel.

Biological traces inside firearm barrels were observed as a result of contact shots to the head. The present study was conducted to investigate the influence of the muzzle to target distance on staining inside the anterior and posterior part of firearm barrels. Ninety-nine shots were fired to so-called reference cubes (10% gelatine, 12 cm edge length, embedded paint-blood-pad) using three current handguns. Shot range was varied from contact to 50 cm distance. High-speed cameras recorded external backspatter. Endoscopic examination assessed visible staining along the barrel. Each two swabbings were gathered from the anterior and the posterior part of the barrel. The first swabs were submitted to quantitative PCR, the second ones to DNA-RNA-co-extraction. Thorough mechanical and chemical cleaning was performed to avoid any contamination which was controlled by negative zero swabs after each cleaning. In single shots up to 50 cm distance, minimal, but DNA-positive sporadic traces were detected inside the barrel in vicinity of the muzzle. Visible complex staining varying in extent was observed in the anterior barrel part for 10 cm or less distance in dependence of the calibre. The posterior part showed detectable traces only after close range shots (< 5 cm). Generally staining inside the barrel decreased from the muzzle to the rear end, which correlated with the yield of DNA. Some contact shots did not cause any staining in the posterior part of the barrel despite massive external backspatter. Blood-specific miRNA was primarily found where DNA was detected. This experience encourages to take a second swab for RNA analysis. The amount of nucleic acids in the barrel at varying muzzle to target distances is subject to large variations between individual shots and therefore appears not suitable for a reliable determination of the shot distance in a particular case on its own. Instead, shot range estimation should also take into account morphology and distribution of traces inside the barrel.

Cat and dog scavenging at indoor forensic scenes: strategies for documentation and detection.

Vertebrate scavenging on human remains is occasionally observed at indoor forensic scenes, especially when pets have access to the body and their deceased owners were socially distanced. Pets feeding on corpses have implications for the forensic investigation, e.g. for trauma analysis and the assessment of the cause of death, the estimation of the postmortem interval (PMI), or the recovery of the complete set of remains. Documentation of potential scavenging in forensic practice is tenuous and needs to be improved in order to be able to use the information for future casework. Investigators need to be aware of the alterations pets can cause to human remains and how these affect further analyses. Following a combined literature review for cat and canine scavenging, we present seven new cases from Switzerland with cat and/or dog involvement. We then created a flowchart guide for a systematic collection of data to use at indoor forensic scenes of suspected scavenging. Our literature review revealed the challenge in discriminating between scavenging by domestic cats and dogs, based on the appearance of the lesions alone. Furthermore, the information that is often routinely collected in indoor fatalities with potential scavenging activity is not sufficient to perform this separation. To provide a practical basis for cat and canine scavenging and its differentiation, we summarise strategies and present a flowchart to use in forensic casework of suspected indoor scavenging.

Study of backspatter using high-speed video of experimental gunshots.

Backspatter is biological material that is ejected from the entry wound against the line of fire. This phenomenon was also observed in wound ballistic simulations using so called "reference cubes" (12 cm edge length, 10% gelatin, 4 °C, paint pad beneath the cover). High-speed video records from 102 experimental shots to these target models using full metal jacketed bullets in the calibers .32 auto, .38 special, 9 mm Luger and .357 Magnum were analyzed for chronology, morphological appearance and velocity of fluid ejection. Generally, a short tail splashing of surface material occurred when the bullet was penetrating the target. In 51 shots from distance (≥ 5 cm), regardless of caliber and shot range, a linear jet of fluid started in connection with the first collapse of the temporary cavity. The initial velocity of the jet was measured between 6 and 45 m/s. The jet was streaming on for about 60 to 100 ms with a stochastic deviation of ± 13° to the horizontal. Close range and contact shots showed earlier and faster (up to 330 m/s) backspatter depending on the cartridge and the gap between muzzle and target. Gaseous aerosol-like spray and cone-like spatter indicated an increasing influence of muzzle gases with decreasing shot range. Even under standardized experimental conditions, variations of backspatter were observed in near/contact shots.

Ballistic gelatine-what we see and what we get.

Since decades, 10% gelatine is used to visualize and estimate the energy transfer of projectiles. The study performed investigates the correlation of the temporary cavity (TC) recorded by high-speed video (HSV) and the cracks in gelatine slices. A total of 36 shots were performed from distance using form-stable bullets (FMJ), 12 using deforming bullets (HP) in the calibres .32 auto, .38 special and 9 mm Luger. The target models were prepared according to Fackler's standard as 10% gelatine cubes with 12 cm edge length doped with a paint pad beneath the front cover ("reference cube"). Scaled images of the TC were recorded with 40.000 fps. The cubes were cut into 1-cm-thick gelatine cross sections, which were scanned. The evaluation of the destruction (cracks) was performed by the mean of image analysis measuring the longest crack, the wound profile according to Fackler and applying the polygon method. The height of the TC was measured each cm along the bullet path. The energy deposited ranged between 54 and 269 J. FMJ caused tubular, HP provoked pear-like TC. The tubular aspect was consistent with the quasi-constant deceleration of FMJ; however, the pear-like TC did not metrically represent the deceleration of HP. The profiles of destruction parameters were convex for both projectile types and did not match the profile of bullet deceleration. The maximum of TC stretching observed in HSV did not coincide with maximum gelatine destruction (crack lengths). The total energy transfer correlated with all considered destruction parameters in their sum; however, the cross-sectional parameters did not reflect the energy transfer per centimetre bullet path. The sum of the TC's heights correlated with the energy deposited, but differently for FMJ and HP. Obviously, the 12-cm reference cube reflects the energy transfer by a bullet as a whole.

Second opinion system for sudden cardiac death cases in forensic practice.

Sudden cardiac death (SCD) represents a considerable percentage of cardiovascular deaths worldwide. The most frequent pathological substrate of SCD is atherosclerotic coronary artery disease (CAD). The other, less common, pathologies which can cause SCD include cardiomyopathies, congenital diseases (including abnormal anatomy), and arrhythmias such as channelopathies, many of which are genetically determined. Autopsies of SCD victims are generally performed by forensic pathologists. In some cases, a third person responsibility could be invoked. While CAD diagnosis at post-mortem examination is not a major challenge for the forensic pathologist, the other rarer diseases may be. In such instances, referral of the hearts to specialized centers with recognized expertise is recommended, and this is particularly important in cases of SCDs of young people. Moreover, in order to avoid the frequent overdiagnosis of a pathological heart, an expert opinion should be sought for even in the presence of a morphologically normal heart. In cases where retention of the heart is not feasible, it is essential to provide an extensive photographic documentation, with the indication of the sampling sites for histological examination. However, some practical aspects, as the criteria for case selection in routine forensic practice are missing. In this paper, we present the recommendations for heart retention for a second expert opinion and the alternative of documentation and sampling for cases where retention is not possible.

Validation and evaluation of measuring methods for the 3D documentation of external injuries in the field of forensic medicine.

Three-dimensional (3D) measurement techniques are gaining importance in many areas. The latest developments brought more cost-effective, user-friendly, and faster technologies onto the market. Which 3D techniques are suitable in the field of forensic medicine and what are their advantages and disadvantages? This wide-ranging study evaluated and validated various 3D measurement techniques for the forensic requirements. High-tech methods as well as low-budget systems have been tested and compared in terms of accuracy, ease of use, expenditure of time, mobility, cost, necessary knowhow, and their limitations. Within this study, various commercial measuring systems of the different techniques were tested. Based on the first results, one measuring system was selected for each technique, which appeared to be the most suitable for the forensic application or is already established in forensic medicine. A body of a deceased, a face and an injury of a living person, and a shoe sole were recorded by 11 people with different professions and previous knowledge using the selected systems. The results were assessed and the personal experiences were evaluated using a questionnaire. In addition, precision investigations were carried out using test objects. The study shows that the hand-held scanner and photogrammetry are very suitable for the 3D documentation of forensic medical findings. Their moderate acquisition costs and easy operation could lead to more frequent application in forensic medicine in the future. For special applications, the stripe-light scanner still has its justification due to its high precision, the flexible application area, and the high reliability. The results show that, thanks to the technological advances, the 3D measurement technology will have more and more impact on the routine of the forensic medical examination.

RNA/DNA co-analysis from bloodstains on aged polyvinyl-alcohol gloves prepared for securing evidence from the hands of victims of fatal gunshot injuries.

In contrast to cumulative techniques (e.g., tape-lift) for qualitative gunshot residues (GSR) analysis, topographic methods are commonly applied to preserve the integrity of evidence from a shooter's or victim's hand in cases of gun-related crimes. Topographic sampling techniques employing adhesive foils, latex, or the polyvinyl alcohol (PVAL) method enable unambiguous sampling of biological and non-biological trace material while preserving its spatial distribution and relation to each other. The PVAL method in particular allows for a topographically veridic and quantitative conservation of traces of GSR and biological stains that are embedded in the PVAL glove, because it completely removes these traces from the hand. The present study investigated the success rates of STR profiling and the detection of blood and brain-specific gene expression from minimal traces of blood splatter as well as parallel to the positive detection of gunshot residues embedded in 17 PVAL gloves taken from the hands of deceased persons in the context of homicide cases in the period between 1996 and 2003. The water-soluble PVAL matrix is shown to be fully compatible with successful STR profiling and the detection of blood- and brain-specific miRNA expression, even after up to 20 years of storage, demonstrating that this sampling technique offers advantages compared to other more simplistic sampling methods like taping.

Distortion of the temporary cavity and its influence on staining in firearm barrels.

After contact shots to the head, biological traces can be found inside the barrel of the firearm. Experimental protocols to generate this sort of staining, using 12 cm gelatin cubes containing thin foil bags filled with acrylic paint, human blood, and radiocontrast agent, have been developed. Previous research on shots fired at a distance has shown the underlay sustaining these gelatin cubes has an influence on experimental results. This study was conducted to investigate the role of the sustaining base of the gelatin blocks during contact shots, and its influence on the staining result inside firearm barrels. Eighteen contact shots were performed using 22 LR, 32 ACP (7.65 Browning) and 9 mm Luger semi-automatic pistols. With each pistol, shots were fired onto six gelatin cubes; three placed upon a rigid platform and three upon an elastic underlay. The shots were recorded by a high-speed video camera as they penetrated the gelatin cube. Any staining present inside the firearm barrels after the shots were fired was documented by endoscopy. Cross sections of the gelatin blocks were then compared to the high-speed video. It was found that the nature of the staining inside the barrel was not influenced by the underlay sustaining the target model. In the experiment using a 9 mm Luger, the rigid counterfort provoked a visible distortion of the temporary cavity, but, cross sectional analysis of the gelatin cubes did not reveal a relevant influence of the sustaining underlay on the crack length in the gelatin. This could be explained by a secondary expansion of the temporary cavity left by the projectile as a consequence of subsequent inflow of muzzle gases.

The reference cube: A new ballistic model to generate staining in firearm barrels.

After contact shots to the head biological traces can be found inside firearm barrels. So far silicone coated, gelatin filled box models were used to generate such staining according to the triple contrast method (mixture of acrylic paint, barium sulfate and blood sealed in a thin foil bag). This study was conducted to develop a transparent ballistic model allowing contact shots. Gelatin filled polyethylene bottles with and without a silicone coat were tested in comparison to non-covered gelatin blocks. Finally, thin foil bags of 5 cm × 5 cm dimension were glued on a synthetic absorbent kitchen wipe on top of which 1 L 10% gelatin solution was molded to create blocks of 8.5 cm length. A kitchen wipe with a paint pad on its inside formed the front of the cube. Three contact shots each with a 9 mm Luger pistol and a .38 special revolver were performed on all model variations. The staining was documented by endoscopy and swabs gathered from both ends of the barrel were analyzed by quantitative PCR. Reliable staining was achieved using the front covered gelatin block with comparable results to the silicone coated box model used before. For further research using ballistic models to simulate a human head a symmetric form of the gelatin block such as a cube is recommended.

RNA/DNA co-analysis on aged bloodstains from adhesive tapes used for gunshot residue collection from hands.

In cases of firearm related fatalities a systematic investigation at the scene of death is indispensable to differentiate between self-inflicted and homicidal gunshot injuries. A common method to preserve gunshot residues (GSR) is their collection using adhesive tapes. However, the biological material gathered at the same time by the tapes would be of special interest if backspatter, ejected from the entrance wound against the direction of fire, could be detected. In the present study we examined the success rate of co-analysis of RNA and DNA recovered from biological traces sampled with adhesive tapes. The material originated from eight cases of fatal gunshots, taken from the hands of suspects or victims, examined 5 to 19 years ago for GSR. For all types of adhesive tapes tested, quantity and quality of the co-extracted nucleic acids was insufficient for successful DNA profiling, but was sufficient for the detection of blood-specific micro RNA (miRNA). In summary, sampling trace evidence from the hands of persons involved in fatal gunshots with adhesive tapes has a long-term detrimental effect on biological traces.

The truth lies within: the reconstructive value of inner livores in a homicide case.

Through the widespread use of postmortem computed tomography, inner livores of the lungs have become a frequently observed phenomenon in the field of forensic medicine. Yet their time-dependent development, notably in comparison with the widely studied external livores, remains poorly understood. We present a unique homicide case where the victim was discovered in supine position with correspondent external livores fixed exclusively on the rear side. Yet upon postmortem computed tomography, the victim presented pronounced inner livores within the depending dorsal areas of both lungs but also vertical sedimentation levels solely within the right lung, suggesting an initial right-hand side position and a postmortem re-positioning of the body. Interestingly, this was consistent with tangible hints of postmortem manipulation on-site. It is likely that this repositioning occurred sometime during the early postmortem interval (<6 h) as the external livores have completely rearranged to the final supine position. The presented case suggests different development patterns of inner and outer livores, highlighting the necessity for controlled studies that explore the formation and fixation processes of livor mortis in internal organs. A better understanding of these issues can prove useful in forensic examinations.

The 'triple contrast' method in experimental wound ballistics and backspatter analysis.

In practical forensic casework, backspatter recovered from shooters' hands can be an indicator of self-inflicted gunshot wounds to the head. In such cases, backspatter retrieved from inside the barrel indicates that the weapon found at the death scene was involved in causing the injury to the head. However, systematic research on the aspects conditioning presence, amount and specific patterns of backspatter is lacking so far. Herein, a new concept of backspatter investigation is presented, comprising staining technique, weapon and target medium: the 'triple contrast method' was developed, tested and is introduced for experimental backspatter analysis. First, mixtures of various proportions of acrylic paint for optical detection, barium sulphate for radiocontrast imaging in computed tomography and fresh human blood for PCR-based DNA profiling were generated (triple mixture) and tested for DNA quantification and short tandem repeat (STR) typing success. All tested mixtures yielded sufficient DNA that produced full STR profiles suitable for forensic identification. Then, for backspatter analysis, sealed foil bags containing the triple mixture were attached to plastic bottles filled with 10% ballistic gelatine and covered by a 2-3-mm layer of silicone. To simulate backspatter, close contact shots were fired at these models. Endoscopy of the barrel inside revealed coloured backspatter containing typable DNA and radiographic imaging showed a contrasted bullet path in the gelatine. Cross sections of the gelatine core exhibited cracks and fissures stained by the acrylic paint facilitating wound ballistic analysis.

Simultaneous analysis of nuclear and mitochondrial DNA, mRNA and miRNA from backspatter from inside parts of firearms generated by shots at "triple contrast" doped ballistic models.

When a firearm projectile hits a biological target a spray of biological material (e.g., blood and tissue fragments) can be propelled from the entrance wound back towards the firearm. This phenomenon has become known as "backspatter" and if caused by contact shots or shots from short distances traces of backspatter may reach, consolidate on, and be recovered from, the inside surfaces of the firearm. Thus, a comprehensive investigation of firearm-related crimes must not only comprise of wound ballistic assessment but also backspatter analysis, and may even take into account potential correlations between these emergences. The aim of the present study was to evaluate and expand the applicability of the "triple contrast" method by probing its compatibility with forensic analysis of nuclear and mitochondrial DNA and the simultaneous investigation of co-extracted mRNA and miRNA from backspatter collected from internal components of different types of firearms after experimental shootings. We demonstrate that "triple contrast" stained biological samples collected from the inside surfaces of firearms are amenable to forensic co-analysis of DNA and RNA and permit sequence analysis of the entire mtDNA displacement-loop, even for "low template" DNA amounts that preclude standard short tandem repeat DNA analysis. Our findings underscore the "triple contrast" method's usefulness as a research tool in experimental forensic ballistics.

Wounding capacity of muzzle-gas pressure.

BACKGROUND: Suicidal gunshot wounds that are caused by ammunition fired from a 9-mm Luger pistol, with direct contact between the gun muzzle and the victim's head, present a serious injury pattern even with full metal jacket bullets. Wound ballistic experiments were performed to clarify whether muzzle gases from the firearm have an additional wounding potential. METHODS: Fifteen head models were prepared as follows: an acryl sphere measuring 14 cm in diameter was completely covered with a layer of silicon that was 3 mm thick. These spheres were filled with 10% gelatine. At 4°C, these models were fired at with a 9-mm Luger pistol, loaded with Quick Defense 1 expanding bullets. Five shots were fired with direct muzzle contact, one shot was fired from a distance of 10 cm, four shots were fired from a distance of 2 m, and five shots were fired from a distance of 4 m. RESULTS: Each projectile penetrated the model; all but one projectile deformed regularly. Each acryl sphere shattered into comminuted pieces but was held together by the silicon cover. The gelatine filling was then cut into slices 1 cm thick, and each slice was optically scanned. An evaluation was performed following both Fackler's Wound Profile method and the polygon procedure method. The pattern of gelatine disruption did not differ in shots from intermediate ranges, but the amount of gelatine destruction was always more extended in the case of muzzle contact shots. Depending on the section of the bullet path, crack lengths were 31% to 133% longer in contact shots. The first centimetre and the second half of the bullet path showed the greatest increase. CONCLUSION: The experimental findings prove the wounding capacity of muzzle gases.

Persistence of biological traces in gun barrels--an approach to an experimental model.

Traces of backspatter in gun barrels after homicidal or suicidal contact shots may be a valuable source of forensic evidence. Yet, a systematic investigation of the persistence and durability of DNA from biological traces in gun barrels is lacking. Our aim was to generate a realistic model to emulate blood and tissue spatters in gun barrels generated by contact gunshots at biological targets and to analyse the persistence and typability of DNA recovered from such stains. Herein, we devise and evaluate three different models for the emulation of backspatter from contact shots: a gelatine-based model with embedded blood bags, a model based on a spongious matrix soaked with blood and covered with a thin plastic membrane and a head model consisting of an acrylic half sphere filled with ballistic gelatine and with blood bags attached to the sphere under a 3-mm silicone layer. The sampling procedure for all three models: a first shot was fired with several types of guns at each model construction and subsequently a second shot was fired at a backstop. Blood samples were collected after each shot by probing the inner surface of the front and rear end of the respective gun barrel with a sterile swab. DNA was then extracted and quantified and up to 20 different short tandem repeat (STR) systems were amplified to generate DNA profiles. Although DNA quantity and STR typing results were heterogenous between the models, all models succeeded in delivering full STR profiles even after more than one shot. We conclude that biological traces in gun barrels are robust and accessible to forensic analysis and that systematic examination of the inside of gun barrels may be advisable for forensic casework.

Visualisation of the temporary cavity by computed tomography using contrast material.

The temporary cavity of a missile produces radial tears in ordnance gelatine, which correlate to the energy transfer. Computed tomography is a useful and non-destructive method to examine gelatine blocks. However, the tears give only few radiocontrast by air filling, which decreases with the time past shooting. Therefore, systematically, a radiocontrast material was searched to enhance the contrast. Different contrast materials were amalgamated to acryl paint, and about 7 g was sealed in a foil bag, which was integrated in the front of a standard 10% gelatine cylinder. Shots with Action-5 expanding bullets were performed from a 5-m distance. Gelatine was scanned by multi-slice computed tomography. The multiplanar reconstructed images were compared to mechanically cut slices of 1 cm thickness. It was shown experimentally that iodine containing water-soluble contrast material did not give sufficient contrast and caused diffusion artefacts. Best results were obtained by barium sulphate emulsion. The amount of acryl paint was sufficient to colour the tears for optical scanning. The radiocontrast of barium leads to satisfying imaging of tears and allowed the creation of a three-dimensional reconstruction of the temporary cavity. Comparison of optical and radiological results showed an excellent correlation, but absolute measures in computed tomographic (CT) images remained lower compared with optically gathered values in the gelatine slices. Combination of paint and contrast material for CT examination will facilitate the evaluation of complex ballistic models and increase accuracy.

[Fall from height--surprising autopsy diagnosis in primarily unclear initial situations]. / Sturz aus der Höhe--uberraschende Sektionsdiagnose bei primär unklarer Ausgangslage.

UNLABELLED: External post-mortem examination and first police assessments are often not consistent with subsequent autopsy results. This is all the more surprising the more serious the injuries found at autopsy are. Such discrepancies result especially from an absence of gross external injuries, as demonstrated by four examples. A 42-year-old, externally uninjured male was found at night time in a helpless condition in the street and died in spite of resuscitation. Autopsy showed severe polytrauma with traumatic brain injury and lesions of the thoracic and abdominal organs. A jump from the third floor was identified as the cause. At dawn, a twenty-year-old male was found dead on the grounds of the adjacent house. Because of the blood-covered head the police assumed a traumatic head injury by strike impact. The external examination revealed only abrasions on the forehead and to a minor extent on the back. At autopsy a midfacial fracture, a trauma of the thorax and abdomen and fractures of the spine and pelvis were detected. Afterwards investigations showed that the man, intoxicated by alcohol, had fallen from the flat roof of a multistoried house. A 77-year-old man was found unconscious on his terrace at day time; a cerebral seizure was assumed. He was transferred to emergency care where he died. The corpse was externally inconspicuous. Autopsy revealed serious traumatic injuries of the brain, thorax, abdomen and pelvis, which could be explained by a fall from the balcony. A 47-year-old homeless person without any external injuries was found dead in a barn. An alcohol intoxication was assumed. At autopsy severe injuries of the brain and cervical spine were found which were the result of a fall from a height of 5 m. CONCLUSION: On the basis of an external post-mortem examination alone gross blunt force trauma cannot be reliably excluded.

Comments on unassisted smothering in a pillow.

A case of homicidal smothering with a pillow is reported. The vital aspiration of fibres was proven by microscopic examination of a tracheobronchial lavage.

Suicide by head explosion: unusual blast wave injuries to the cardiovascular system.

A 57-year-old employee in a military scientific institute was found acephalous in a supine position in an anteroom to the bunker. On the walls was abundant spattering of blood and tissue, concentrated above shoulder height. A mobile ignition device stood on the control desk. The complete destruction of the head down to the cervical spine suggested that the explosive charge (RDX) detonated in his mouth. The hands were virtually uninjured. The pressure effect in vessels caused numerous tears to the wall of the carotid arteries and the left vertebral artery, a tear-off of the left carotid artery of the aortic arch, and a 2.5-cm long crack of the thoracic aorta with 540-ml blood in the pericardial sac and a shredded window-like disruption of the left aortic valve cusp. The autopsy also showed an infraction of the sternum from the inside, and a contusion of the superior lobes of both lungs. The trace pattern on the right arm suggested suicide. A bone fragment of the mandible penetrated the right biceps muscle as a secondary projectile.