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Two men were wrongfully convicted of murder in 2017 and sentenced to life imprisonment. After a physical altercation inside a flat, the victim (A) was found dead approximately 60 m away outside a residential address. He had sustained a number of injuries including a stab wound to the left side of his neck which was found to have divided the right carotid artery. The location where A was found was not regarded as a crime scene and not subjected to a specialist forensic examination by scientists as it was assumed that the fatal injury was sustained in the flat. The pathologist, who subsequently carried out the autopsy on A, was not asked to attend the scene. A review of the blood distribution at the scene in conjunction with the pathology findings indicated however that the fatal neck wound had been inflicted outside the flat, near to where the victim was found. An appeal against the convictions for murder was upheld in 2021 and a re-trial ordered. Following this second trial, both accused were acquitted of murder and released from custody. The new pathology and blood pattern evidence introduced at the second trial was a major part of the defense strategy which led to the acquittal of the accused. The case illustrates that a more inclusive and detailed crime scene strategy had been undertaken, including an assessment of the bloodstains present, in conjunction with discussion with the pathologist, then the likelihood is that the two men subsequently charged with murder would have been eliminated as suspects and a miscarriage of justice would have been avoided. [ABSTRACT FROM AUTHOR]

Insects found at a crime scene can produce traces referred to as fly artifacts (FA) due to their movement over the corpse and the manner in which they feed upon it. These can be detrimental for carrying out criminal investigations. Confusing a FA with a genuine bloodspot can lead to misinterpretations, also taking into consideration that FA may contain a human DNA profile. The aim of the present study was to employ scanning electron microscopy (SEM) for the analysis of FA produced by Calliphora vomitoria on hard surfaces and fabrics that are commonly present at crime scenes. FA and control bloodstains were produced under experimental conditions on metal, glass, plaster, cotton, and polyester. After macroscopic analysis, FA were examined at standard low (20–40 ×), medium low (300–600 ×), and high ultrastructural (1200 ×) magnification through a SEM Stereoscan 360, Leica, Cambridge. SEM analysis enabled the identification of distinctive features of FA on hard surfaces, namely, amorphous crystals, micro-crystals with a morphology similar to those of uric or micro-crystals with a comparable morphology to cholesterol, absent in controls. Moreover, red blood cells (RBC) were absent in FA but were always present in controls. On cotton, for both FA and controls, the drop was almost completely absorbed and thus indistinguishable from the underlying fabric texture. On polyester, FA showed amorphous/crystal-like deposits and no RBC, as observed on hard surfaces, except for those showing a completely flat surface. SEM analysis appeared to be suitable for differential diagnosis between FA and genuine bloodstains on hard surfaces, although the results may be inconclusive on tested fabrics. [ABSTRACT FROM AUTHOR]

Fly artifacts resulting from insect activity could act as confounding factors on a crime scene and interfere with bloodstain pattern analysis interpretation. Several techniques have been proposed to distinguish fly artifacts from human bloodstains based on morphological approach and immunological assay, but a DNA-based method has not been developed so far. Even if in forensic genetic investigations the detection of human DNA is generally the primary goal, fly artifacts can provide useful information on the dynamics of crime events. The present study provides a molecular method to detect fly DNA from artifacts deposited by Calliphora vomitoria after feeding on human blood through the analysis of the mitochondrial cytochrome oxidase gene subunit I (COI). Fly artifacts originated from digestive process and of different morphology spanning from red and brownish/light brown, circular and elliptical stains to artifacts with sperm-like tail or a tear-shaped body were collected. The COI amplification was successfully obtained in 94% of fly artifact samples. The method showed high sensitivity and reproducibility, and no human DNA contamination was observed, offering specificity for use in confirmatory test. This molecular approach permits the distinction of fly artifacts from genuine bloodstains and the identification of fly's species through the COI region sequencing by protocols usually applied in forensic genetic laboratories. [ABSTRACT FROM AUTHOR]

For investigative purposes, the bloodstain pattern analyst might have to estimate whether a given stain on fabric could have originated from a specific location. A wide range of values of the maximum distance that a blood drop can travel have been reported based on experiments, ranging from less than 1 m to more than 10 m. It is also known that stains on porous materials such as fabrics are more difficult to interpret than stains on non-absorbing surfaces, because of wicking. Here, we perform several fluid dynamic spatter experiments and formulate a fluid dynamics model to describe the trajectories of the blood drops. The experiments are performed with swine blood, the properties of which are well understood. The main parameters screened are the drop size, initial velocity, the launch angle, and the orientation of the fabric. A large number of blood drops are produced by impact events. The resulting stains on knitted white T-shirt fabric are digitally measured. Their position relative to the source and size is reported. Trajectories are simulated accounting for the influence of gravity and drag forces. A simple relation between drop size and stain size is established based on extensive experiments on a specific fabric. Results of the trajectory simulations are then searched and mined for parameters directly measurable on a crime scene, such as the stain size on fabric and the relative location of the fabric with respect to the blood source. The experimental results are compared and found in agreement with the numerical predictions. The results are presented in one chart relevant to crime scene reconstruction. The chart is easy to use and only requires minimum knowledge of fluid dynamics. [ABSTRACT FROM AUTHOR]

Courtrooms are asking for reliable scientific evidence in order to prevent wrongful convictions. Thus, a more rigorous approach to forensic science approved by scientific methods is promoted. The study of human blood dynamics in the context of forensic science is becoming a widespread research topic, although the physics behind wetting and drying of blood is not completely understood. Based on the morphological changes of drying blood pools, the following work presents a patentable method to quantitatively date these blood pools for forensic purposes. As for drying drops of blood, cracking patterns are observed but they are more disordered. Similar disordered crack patterns are observed in the case of gels, their evaporation process is, therefore, presented since this topic has been thoroughly investigated. We aim to find reliable patterns that could give information concerning the evolution of a blood pool over time to lead to practical application of this knowledge. An empirical model is established between final dried blood patterns and the generating mechanism, yielding application in bloodstain pattern analysis for forensic investigations. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis has a key role in crime scene reconstruction; however, it can be hampered by diverse confounding factors, such as insect activity which may lead to the production of small artifactual bloodstains, commonly referred to as fly artifacts (FA). Although several techniques aimed at distinguishing human bloodstains and FA have been developed, actually, no standardized and reproducible methodology is available. The aim of our study was to test the use of scanning electron microscopy (SEM) to distinguish human bloodstains from FA produced by Sarcophaga carnaria. FA and bloodstains have been produced on five different deposition surfaces under experimental conditions. After visual analysis, bloodstains and FA were analyzed at standard low (× 40–× 300) and high (× 600–× 1200) magnification through a Philips SEM 515. Although differential diagnosis between bloodstains and FA resulted often inconclusive at visual analysis, SEM analysis allowed the identification of additional key distinctive morphological features. In particular, on the surface of FA, small crystal-like and/or amorphous material deposits were observed. Such deposits were absent on bloodstains which, on the other hand, displayed red blood cells stacked in "rouleaux." Basing on these results and under our experimental conditions, SEM analysis resulted suitable to perform a differential diagnosis between bloodstains and FA produced from the insect activity of Sarcophaga carnaria. [ABSTRACT FROM AUTHOR]

A recurrent observation in forensic casework is that culprits and/or their abettors attempt to remove or mask bloodstain patterns, e.g., by painting the walls. The present study was designed to elucidate whether luminol treatment of bloodstains on (a) plastered and (b) wallpapered walls may help with the visualization of respective patterns after being repainted beyond macroscopic recognition. Furthermore, wallpaper punches of luminol-positive spots were analyzed for DNA. The experiments showed that the prospects for visualization after a four- to sixfold paint application declined considerably as the drying time of the paint increased. A compelling explanation for this observation is that paint becomes increasingly resistant to water during the drying process after paint application. In these cases, moistening the surface in question with distilled water for 15 min has been proven to be a promising pretreatment before luminol application. DNA analysis revealed full STR profiles in 74% of luminol-positive wallpaper punches, whereas rubs of the aforementioned positively tested regions (luminol and human blood pretests) demonstrated negative results. [ABSTRACT FROM AUTHOR]

The analysis of blood traces is often of significant reconstructive and evidence-gathering importance. Perpetrators deliberately set fires to destroy evidence. There is little literature regarding the effect of fire and extreme heat on blood and the detection of blood. Blood and DNA are believed to be no longer traceable after exposure to a temperature of 1000 °C. This study exposed different objects of a standardized procedure to temperatures of 300, 700, and 1000 °C. It documented the influence of heat on blood traces through the use of luminol. DNA analysis confirmed that fewer DNA profiles can be created with increasing temperature. However, even after exposure up to a max. of 1000 °C, it was still possible to produce a complete DNA pattern from approx. 60% of the samples. Consequently, crime scenes that have been destroyed by fire should be evaluated with the same attention to detail as the unburned areas. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis (BPA) is the forensic discipline concerned with the classification and interpretation of bloodstains and bloodstain patterns at the crime scene. At present, it is unclear exactly which stain or pattern properties and their associated values are most relevant to analysts when classifying a bloodstain pattern. Eye tracking technology has been widely used to investigate human perception and cognition. Its application to forensics, however, is limited. This is the first study to use eye tracking as a tool for gaining access to the mindset of the bloodstain pattern expert. An eye tracking method was used to follow the gaze of 24 bloodstain pattern analysts during an assigned task of classifying a laboratory-generated test bloodstain pattern. With the aid of an automated image-processing methodology, the properties of selected features of the pattern were quantified leading to the delineation of areas of interest (AOIs). Eye tracking data were collected for each AOI and combined with verbal statements made by analysts after the classification task to determine the critical range of values for relevant diagnostic features. Eye-tracking data indicated that there were four main regions of the pattern that analysts were most interested in. Within each region, individual elements or groups of elements that exhibited features associated with directionality, size, colour and shape appeared to capture the most interest of analysts during the classification task. The study showed that the eye movements of trained bloodstain pattern experts and their verbal descriptions of a pattern were well correlated. [ABSTRACT FROM AUTHOR]

In an attempt to obtain a deeper understanding of the factors which determine the characteristics of expirated bloodstain patterns, the mechanism of formation of airborne droplets was studied. Hot wire anemometry measured air velocity, 25 mm from the lips, for 31 individuals spitting, coughing and blowing. Expirated stains were produced by the same mechanisms performed by one individual with different volumes of a synthetic blood substitute in their mouth. The atomization of the liquid at the lips was captured with high-speed video, and the resulting stain patterns were captured on paper targets. Peak air velocities varied for blowing (6 to 64 m/s), spitting (1 to 64 m/s) and coughing (1 to 47 m/s), with mean values of 12 m/s (blowing), 7 m/s (spitting) and 4 m/s (coughing). There was a large (55-65%) variation between individuals in air velocity produced, as well as variation between trials for a single individual (25-35%). Spitting and blowing involved similar lip shapes. Blowing had a longer duration of airflow, though it is not the duration but the peak velocity at the beginning of the air motion which appears to control the atomization of blood in the mouth and thus stain formation. Spitting could project quantities of drops at least 1600 mm. Coughing had a shorter range of near 500 mm, with a few droplets travelling further. All mechanisms could spread drops over an angle >45°. Spitting was the most effective for projecting drops of blood from the mouth, due to its combination of chest motion and mouth shape producing strong air velocities. No unique method was found of inferring the physical action (spitting, coughing or blowing) from characteristics of the pattern, except possibly distance travelled. Diameter range in expirated bloodstains varied from very small (<1 mm) in a dense formation to several millimetres. No unique method was found of discriminating expirated patterns from gunshot or impact patterns on stain shape alone. Only 20% of the expirated patterns produced in this study contained identifiable bubble rings or beaded stains. [ABSTRACT FROM AUTHOR]

In forensic case work, blood stain pattern analysis frequently aids in deducing the chain of actions or parts thereof taking place during an event leading to blood loss. Wiped single blood stains and/or groups of blood stains are seen at a majority of complex crime scenes. The appearance of wiped blood stains depends on droplet volume and stain age (as a function of blood viscosity and the degree of stain skeletonization) and characteristics of the stained surface (i.e., texture, temperature). Furthermore, based on the biochemical and biophysical properties of blood, not only the drying processes, but also complex coagulation cascades are relevant to the assessment of wiped blood stains. This study was designed to determine if anticoagulation therapies markedly affect the wipeability of blood stains over times elapsed since deposition and the overall drying process. A total of 813 blood stains, originating from donors being treated with acetylsalicylic acid (ASA), clopidogrel + ASA, low-molecular-weight heparin, or rivaroxaban, were dropped on common household tiles. Wipeability at an ambient temperature of 20 °C was tested for 22 time periods (1, 2, 3, 5, 10, 15...105 min since deposition). Whereas stains consisting of untreated blood were dried within 55 min, wipeability of all droplets originating from donors with prior anticoagulation treatment showed pronounced delays compared with the control, ranging from 20 min (ASA and clopidogrel + ASA) to 45 min (rivaroxaban). This pronounced effect was not seen in earlier studies, which might be explained by the higher volume of droplets used in this study, which resulted in a shift in relevance from drying to clotting processes. Significant differences between the drying times of the various anticoagulation regimes might be attributed to anticoagulant activity against different targets in the coagulation cascades. In conclusion, anticoagulation treatment prior to blood loss significantly affected the wipeability of blood stains. Anticoagulation therapy should therefore be taken into account in the analysis of blood stain patterns. [ABSTRACT FROM AUTHOR]

Copyright of Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Whenever blunt or sharp forces are used in a crime, analysis of bloodstain pattern distribution may provide important information for the reconstruction of happenings. Thereby, attention should be paid to both the crime scene and the clothes of everyone involved in the crime. On dark textiles, though, it is difficult or even impossible for the human eye to detect bloodstains because of the low contrast to the background. However, in the near infrared wavelength range, contrast is considerably higher. Many textiles reflect light beyond a wavelength of 830 nm and thus appear light-colored, whereas blood absorbs the light and appears dark. In our studies, a D7000 NIKON reflex camera modified for infrared photography produced high-resolution photographs visualizing even very small spatter stains on dark textiles. The equipment can be used at any crime scene or lab and provides immediately available and interpretable images. Thus, important findings can be obtained at an early stage of police investigations, as two examples (homicide and attempted homicide) illustrate. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis is occasionally required in practical forensic casework. Misinterpretations may occur in cases in which diluted bloodstains are formed either within the course of the crime or during cleaning attempts after the original crime. The resulting pale or diluted aspect of the bloodstains may also be produced by passive serum separation. To differentiate between diluted and non-diluted stains and the artifacts of pure serum separation, dripping experiments were performed using droplets of multiple sizes and dilutions dripped onto common indoor and fabric surfaces. In addition, pools of blood of different volumes were applied to solid surfaces with different inclinations to determine the conditions and properties of serum separation. This study yielded morphological characteristics that enable differentiation between stains of diluted and non-diluted blood: a prominent ring phenomenon indicates dilution with water. To elucidate the underlying physical mechanism of particle distribution within a blood stain, photomicrographs were taken during the drying process. The so-called contact line pinning effect was identified as the formation mechanism of this ring phenomenon. Serum separation was highly dependent on the applied blood volume, the ambient temperature, the time elapsed since the initial deposition, and the degree of floor inclination. [ABSTRACT FROM AUTHOR]

Textiles may provide valuable bloodstain evidence to help piece together events or activities at violent crime scenes. However, in spite of over 75 years of research, there are still difficulties encountered in many cases in the interpretation and identification of bloodstains on textiles. In this study, we dripped porcine blood onto three types of fabric (plain woven, single jersey knit, and denim) that are supported in four different ways (hard, taut, loose, and semi-hard, i.e., fabric laid on denim). These four mounting methods represent different ways in which a textile may be present when blood from a violent act lands on it. This study investigates how the fabric mounting method and backing material affect the appearance of drip stains on textiles. We found that bloodstain patterns formed on fabric lying flat on a hard surface were very different from when the same fabric was suspended loosely. We also found that bloodstains formed on the technical back of single jersey knit were vastly different from those on the technical face. Interestingly, some drip stains showed blood passing through the textile and leaving a stain behind it that resembled insect stains. By observing, recording, and describing how a blood stained textile is found or presented at the scene, the analyst may be able to better understand bloodstains and bloodstain patterns on textiles, which could be useful to confirm or refute a witness's account of how blood came to be where it was found after a bloodshed event. [ABSTRACT FROM AUTHOR]

Blood expirated from the nose may leave a characteristic bloodstain at a crime scene which can provide important clues for reconstructing events during a violent assault. Little research has been done on the typical velocities, trajectories and size distribution that can be expected from expirated blood. An experimental fluid dynamics technique known as stereoscopic particle image velocimetry is used in this work to obtain the air velocity field inside and outside the nostrils during exhalation. A numerical model was then used to compute the trajectory of blood drops of 0.5 and 2 mm. The drops were tracked until ground plane impact below the nostril exit. Three heights were investigated, 1.5, 1.6 and 1.7 m. For an expiration flow rate of 32 l/min in vivo, there is a maximum exit velocity from the nostril of approximately 4 m/s, with a 0.5 m/s difference between nostrils. After the drops have traversed the distances investigated, drops of 0.5 and 2 mm in diameter from both nostrils are at a similar velocity. This implies that the gravitational acceleration after the drops leave the jet has the most influence on velocity. It is however shown that exit velocity does affect impact location. Drop size affects both impact location and impact velocity. An increase in height increases the distance traversed. Compared to the 2-mm drop, the 0.5 mm had a lower impact velocity, but its impact location in the ground plane was further from the nostril exit. Understanding the physics of expirated blood flight allows better interpretation of expirated stains at crime scenes. [ABSTRACT FROM AUTHOR]

Copyright of Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Surgeons face an occupational risk of daily exposure to blood and body fluids. Potential sources of infection include sharps injuries and mucocutaneous contact. The transmission of blood-borne viruses, in particular human immunodeficiency virus (HIV), Hepatitis B and Hepatitis C from the patient to healthcare workers is well documented in the literature. We studied the incidence and degree of blood splash in all otolaryngology (ENT) procedures undertaken in a single unit over a 12 week period. In addition, we investigated which intraoperative factors might predict the degree of splash. We undertook a prospective, non-blinded study of 102 patients undergoing a range of 'routine' elective ENT within one department over 12 weeks. A surgical mask with visor attached was worn in all procedures. Following each procedure, all splatter masks were collected and examined macroscopically and microscopically for blood splash. In addition, the procedure performed, technique used, total blood loss, operating time and grade of surgeon was noted. 54 % of procedures resulted in splash mask contamination. The median number of splash spots per mask was 4.7 (range 0-63). Tonsillectomy was the most commonly performed procedure, accounting for over one-third of total procedures investigated. Each mask had an average of 8.2 splash marks. Tonsillectomy had a splash rate of 76.9 %. Although the risk of developing HIV is low the operating surgeon has a duty to take all precautions to protect themselves during a procedure and therefore a protective mask and visor or suitable goggles must be worn. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis is a routine procedure in forensic cases that involve bleeding wounds. It utilizes geometric principles to determine the sequence of actions causing the bloodshed and the area of origin, that is, from where the blood originated. The patterns formed by circular bloodstains from drops of blood that hit adjacent surfaces at a 90-degree angle are thought to provide indications of the height of the impact. In this study, blunt force exerted against a pool of blood, which was used as a surrogate for a bleeding wound, was carried out for five different impact-to-wall distances. The blunt force consisted of a hammer head that was dropped from a height of 1.5 m. High-speed photography of the impact and trajectories of the projected blood droplets was analysed. The patterns containing bloodstains produced by the droplets were analysed by measuring the circular bloodstains within the patterns. All the experiments showed that there were two distinct patterns or clusters of circular bloodstains that occurred at different heights above the impact site. The two patterns were a result of different fractions of blood that were projected in a garland or crown-like form of a 'Worthington splash' after impact. The findings suggest that patterns of circular bloodstains cannot be used as direct indicators of impact height, but combined analysis of their clusters may lead to indirect determination of impact-to-wall distance and area of origin. [ABSTRACT FROM AUTHOR]

Copyright of Wiener Medizinische Wochenschrift is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Wiener Medizinische Wochenschrift is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The introduction of multi-voxel pattern analysis (MVPA) to the functional magnetic resonance imaging (fMRI) community has brought a deeper appreciation for the diverse forms of information that can be present within fMRI activity. The conclusions drawn from MVPA investigations are frequently influenced by both the ability to decode information from multi-voxel patterns and mean activation levels. In practice, MVPA studies vary widely in why and how they test for differing overall response levels. In this article, I examine the place of univariate information in MVPA investigations. I first discuss the variety of interpretations given to finding univariate response differences. I go on to discuss some of the analysis approaches used to investigate and compare univariate and multivariate sources of information, which can illuminate their respective contributions. It will be important for the MVPA and general fMRI community to continue to discuss and debate these important issues. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis (BPA) is the investigation and interpretation of blood deposited at crime scenes. However, the interaction of blood and apparel fabrics has not been widely studied. In this work, the development of bloodstains (passive, absorbed and transferred) dropped from three different heights (500, 1,000, 1,500 mm) on two cotton apparel fabrics (1 × 1 rib knit, drill) was investigated. High-speed video was used to investigate the interaction of the blood and fabric at impact. The effect of drop height on the development of passive, absorbed and transferred bloodstains was investigated using image analysis and statistical tools. Visually, the passive bloodstain patterns produced on the technical face of fabrics from the different drop heights were similar. The blood soaked unequally through to the technical rear of both fabrics. Very little blood was transferred between a bloody fabric and a second piece of fabric. Statistically, drop height did not affect the size of the parent bloodstain (wet or dry), but did affect the number of satellite bloodstains formed. Some differences between the two fabrics were noted, therefore fabric structure and properties must be considered when conducting BPA on apparel fabrics. [ABSTRACT FROM AUTHOR]

When blood reaches an extracorporeal surface, a drying process is initiated. Properties of this drying process may be crucial for the correct assessment of case-specific time lapses, however, there is a lack of systematic studies concerning the drying times of blood. We present a study on drying properties of small blood droplets with a standardized size of 25 μl (resembling droplets originating from pointed and sharp objects, e.g. the tip of a knife) under different environmental conditions to elucidate the effect of different ambient temperatures, indoor surfaces and anticoagulant treatment. As a rule of thumb, wiping a typical small blood droplet will not lead to a macroscopically visible smear after a time period of approximately 60 min (time = 45 min; time = 75 min) at an average room temperature of 20 °C. Alteration of the ambient temperature has a remarkable effect, as the time needed for the drying process leading to wipe resistance of the droplets decreases to 30 min (time) at an ambient temperature of 24 °C, and is prolonged up to >120 min (time) at an ambient temperature of 15 °C. As for the surface materials in our study, significant differences in drying periods were only found between wood and linoleum (80th percentile 45 vs. 75 min). Treatment with anticoagulants did not influence extracorporeal drying times. In synopsis, the present study shows that ambient temperature is a major determinant of the drying process of blood droplets and should always be documented accurately and continuously on a crime scene. In certain situations, an estimation of the time elapsed since bloodstain origination may be of importance to answer questions related to the time course of actions. However, further systematic studies are needed to clarify the effect of other properties such as droplet size, humidity, or evaporation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

During forensic investigations, it is often important to be able to distinguish between impact spatter patterns (blood from gunshots, explosives, blunt force trauma and/or machinery accidents) and bloodstain patterns generated by expiration (blood from the mouth, nose or lungs). These patterns can be difficult to distinguish on the basis of the size of the bloodstains. In this study, high-speed digital video imaging has been used to investigate the formation of expirated bloodstain patterns generated by breathing, spitting and coughing mechanisms. Bloodstain patterns from all three expiration mechanisms were dominated by the presence of stains less than 0.5 mm in diameter. Video analysis showed that in the process of coughing blood, high-velocity, very small blood droplets were ejected first. These were followed by lower velocity, larger droplets, strands and plumes of liquid held together in part by saliva. The video images showed the formation of bubble rings and beaded stains, traditional markers for classifying expirated patterns. However, the expulsion mechanism, the distance travelled by the blood droplets, and the type of surface the blood was deposited on were all factors determining whether beaded stains were generated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis (BPA) refers to the collection, categorization and interpretation of the shape and distribution of bloodstains connected with a crime. These kinds of stains occur in a considerable proportion of homicide cases. They offer extensive information and are an important part of a functional, medically and scientifically based reconstruction of a crime. The following groups of patterns can essentially be distinguished: dripped and splashed blood, projected blood, impact patterns, cast-off stains, expirated and transferred bloodstains. A highly qualified analysis can help to estimate facts concerning the location, quality and intensity of an external force. A sequence of events may be recognized, and detailed questions connected with the reconstruction of the crime might be answered. In some cases, BPA helps to distinguish between accident, homicide and suicide or to identify bloodstains originating from a perpetrator. BPA is based on systematic training, a visit to the crime scene or alternatively good photographic documentation, and an understanding and knowledge of autopsy findings or statements made by the perpetrator and/or victim. A BPA working group has been established within the German Society of Legal Medicine aiming to put the knowledge and practical applications of this subdiscipline of forensic science on a wider basis. [ABSTRACT FROM AUTHOR]

The objective of this study was the development of an accurate and sensitive method for the determination of gamma-hydroxybutyric acid (GHB) in dried whole blood samples using a GC-MS method. The complete procedure was optimized, with special attention on the sample pretreatment, and validated. Therefore, dried blood spots of only 50 μl were prepared and, after the addition of internal standard GHB-d6, directly derivatized using 100 μl of a freshly prepared mixture of trifluoroacetic acid anhydride and heptafluorobutanol (2:1). The derivatized extract was injected into a gas chromatograph coupled to a mass spectrometer (GC-MS), operating in the electron impact mode, with a total run time of 12.3 min. Method validation included the evaluation of linearity, precision, accuracy, sensitivity, selectivity, and stability. A weighting factor of 1/ x was chosen and acceptable intra-batch precision, inter-batch precision, and accuracy were seen. The linear calibration curve ranged from 2 to 100 μg/ml, with a limit of detection of 1 μg/ml. Our procedure, utilizing the novel approach of direct 'on spot' derivatization followed by analysis with GC-MS, proved to be reliable, fast, and applicable in routine toxicology. [ABSTRACT FROM AUTHOR]

Copyright of Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bloodstain Pattern Analysis is a forensic discipline in which, among others, the position of victims can be determined at crime scenes on which blood has been shed. To determine where the blood source was investigators use a straight-line approximation for the trajectory, ignoring effects of gravity and drag and thus overestimating the height of the source. We determined how accurately the location of the origin can be estimated when including gravity and drag into the trajectory reconstruction. We created eight bloodstain patterns at one meter distance from the wall. The origin's location was determined for each pattern with: the straight-line approximation, our method including gravity, and our method including both gravity and drag. The latter two methods require the volume and impact velocity of each bloodstain, which we are able to determine with a 3D scanner and advanced fluid dynamics, respectively. We conclude that by including gravity and drag in the trajectory calculation, the origin's location can be determined roughly four times more accurately than with the straight-line approximation. Our study enables investigators to determine if the victim was sitting or standing, or it might be possible to connect wounds on the body to specific patterns, which is important for crime scene reconstruction. [ABSTRACT FROM AUTHOR]