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Aspiration of blood is a phenomenon observed in violent and natural death scenarios. Bloodstain patterns evolving from expectoration of aspired blood may look suspicious of a violent genesis and thus mislead crime scene investigators. In the present case, a woman was found lying in a pool of blood on the kitchen floor. Furthermore, bloodstains covered her face, clothing, and surrounding furniture and walls. Bloodstain pattern analysis and medicolegal inspection of the suspected scene of crime were carried out and revealed dispersed stains with enclosed gas bubbles in the absence of signs of physical violence leading to the assessment of a natural manner of death. The bloodstains were attributed to expiration of blood because of an internal bleeding. Medicolegal autopsy confirmed the on-site diagnosis as a fatal esophageal varix rupture was found. [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]

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]

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]