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• There are at least ten different methods to classify bloodstain patterns. • Most of the current methods are mechanistic and prone to contextual bias. • A lack of clearly defined, unambiguous classification criteria is a key limitation. • An unambiguous method for bloodstain classification resolves current limitations. • Further research in statistical descriptions and fluid dynamics is required. Classifying bloodstains is an essential part of Bloodstain Pattern Analysis. Various experts have developed methods. Each method considers the same basic bloodstain pattern types. These use either terminology based on the observable characteristics or the mechanistic cause of the bloodstain patterns as part of the classification process. This review paper considers ten classification methods from fourteen sources, which are used to classify bloodstain patterns. There are fundamental differences in how the patterns are classified, how differentiated the classification is, and whether the classification process uses clear, unambiguous criteria, and is susceptible to contextual bias. Experts have also reported issues with classifying bloodstains that have indistinguishable features. These differences expose key limitations with current classification methods: mechanistic terminology is too heavily relied on, and the classification process is susceptible to contextual bias. The development of an unambiguous classification method, based on directly observable characteristics within bloodstain patterns is recommended for future work. [ABSTRACT FROM AUTHOR]

As humanity advances into a space-faring species, the risk of injury by multiple means and intentions will follow. Expanding understanding of how forensic science adapts to extraterrestrial environments is a novel and inevitable expansion into the next forensic frontier. This study considers the unique challenges of bloodstain pattern analysis in microgravity environments. Specifically, observation in novel experimentation aboard a parabolic flight research airplane which yielded fluid dynamic behaviors in a microgravity environment that provides practical understanding of Earth-based and off-world bloodstain applications.

• 21 Bloodstain pattern analysts examined 6 self-selected prepared stain patterns. • They calculated the AO which was compared with FARO 3D software performance. • The maximum error for any one impact analysis was identified as 24.27 cm deviation. • An absolute average error rate of 5.62 cm was established. • None of the values exceeded the 30 cm acceptable allowance. In a bloodletting incident, the area of origin (AO) of an impact bloodstain pattern is crucial when establishing the sequence of events. The use of laser scanners and other three-dimensional (3D) technologies to document and analyse bloodstains have been the subject of previous papers, especially where AO analysis is concerned. FARO Zone 3D (FZ3D) is a relatively new software programme that can be used for bloodstain AO analysis. FZ3D requires a greater understanding of inter-observer errors associated with AO. This study looked at the inter-observer variation between 21 examiners when repeatedly calculating the AO six times for a single impact pattern on a plain white wall. An impact rig which consisted of a spring tension arm was positioned and fixed 45 cm from the X wall (right wall), and 45 cm from the Y wall (left wall). This experimental design resembles an impact blow for a bloodletting event. The AO was unknown to all examiners, making it a blind study. The collected results were documented in a Microsoft Excel datasheet and later analysed. From previous literature, a 30 cm acceptable allowance was utilised for AO analysis; however, there is currently no accepted standard error for this type of analysis. The overall total 3D mean error for all examiners was 5.62 cm. The maximum error for any one impact analysis was 24.27 cm. The variation of the data, which was collected by all examiners, was documented as X = 1.14 cm, Y = 1.24 cm, Z = 1.68 cm, and the total 3D error = 2.28 cm. The total 3D error for any one examiner and the variance between examiners did not exceed the 30 cm acceptable allowance utilised in previous literature. [ABSTRACT FROM AUTHOR]

• Whole bovine blood with ACD-A anticoagulant is an appropriate blood source for basic BPA research. • This blood source with ACD-A can be stored in ambient conditions. • The concentration volume of ACD-A anticoagulant added influences fluid properties. • DFF Fluid properties change predictably over time similarly to previous research. Mammalian whole blood sources are often used for forensic research and training when human samples cannot be sourced. While porcine, ovine and equine blood have been shown to be viable alternatives to whole human blood for forensic purposes, procurement can still pose a problem, especially for smaller and remote institutions. This work explores the use of whole bovine blood for basic bloodstain simulation. Sample preparation through the addition of ACD-A anticoagulant was optimized and storability was explored. Viscosity, surface tension, density, and packed cell volume, four fluid properties relevant to bloodstain pattern analysis, were monitored over four days and in two temperature conditions. Linear mixed models accounting for variation in the donor demonstrated that these fluid properties of the bovine blood changed predictably over time and with temperature. Whole bovine blood with 12.5% v/v ACD-A was found to be viable for use in basic bloodstain simulation at ambient and physiological temperature. [ABSTRACT FROM AUTHOR]

Cast‐off stains are common patterns found at crime scenes involving blood shedding events. However, the analysis and interpretation of cast‐off patterns remains an area lacking tools for crime scene investigators. Analyzing cast‐off patterns may allow investigators to interpret the area from where an object may have been swung and thus determine the approximate location of a suspect or victim. This study looked at the position and distribution of cast‐off patterns and area of origin as a starting point for the development of a method to analyze cast‐off patterns. Through a series of tests using a controlled cast‐off rig (n = 10), it was observed that a Path Volume Envelope (PVE) may be identified where the swinging path is contained in a volume along with an area of exclusion. The calculated center, linear position of the PVE was found to have an average error of just over 3.2 cm when compared to the known object swing path position. The maximum deviation of the PVE to the known swing path was found to be 5.0 cm with a standard deviation of 1.4 cm. Additional studies are required to investigate the effects of partial cast‐off stains, wielded object velocity, direction of swing, distance from the projected surface, and other factors. The observations and analysis from this study were seen to be predictable and repeatable and may provide a possible new method for investigators to interpret cast‐off stains. [ABSTRACT FROM AUTHOR]

The forensics discipline of bloodstain pattern analysis plays an important role in crime scene analysis and reconstruction. One reconstruction question is whether the blood has been spattered via gunshot or blunt impact such as beating or stabbing. This paper proposes an automated framework to classify bloodstain spatter patterns generated under controlled conditions into either gunshot or blunt impact classes. Classification is performed using machine learning. The study is performed with 94 blood spatter patterns which are available as public data sets, designs a set of features with possible relevance to classification, and uses the random forests method to rank the most useful features and perform classification. The study shows that classification accuracy decreases with the increasing distance between the target surface collecting the stains and the blood source. Based on the data set used in this study, the model achieves 99% accuracy in classifying spatter patterns at distances of 30 cm, 93% accuracy at distances of 60 cm, and 86% accuracy at distances of 120 cm. Results with 10 additional backspatter patterns also show that the presence of muzzle gases can reduce classification accuracy. [ABSTRACT FROM AUTHOR]

This comparative study aimed to investigate the differences between the workflow, accuracy, and reproducibility of the area of origin tools in FARO Scene and FARO Zone 3D software. Released in 2018, FZ3D has recently been introduced as an alternative application to FARO Scene's Forensic Wizard plug-in for bloodstain pattern analysis but no accuracy studies have been published at the time of this study. A total of 15 impacts were created using an impact rig at three different positions from two orthogonal walls (50cm, 75cm, 100cm). One researcher conducted the analyses with both software packages, and the total errors using FZ3D were not statistically greater than using FARO Scene (p>0.05). With FZ3D, 50% of the total errors ranged from 6.63cm to 15.68cm with a minimum of 2.45cm, maximum of 27cm, and median of 11.22cm. With FARO Scene, 50% of the total errors ranged from 3.6cm to 15.5cm with a minimum of 2.93cm, maximum of 31.25cm and median of 9.6cm. A blind test with seven participants analyzing the same 15 impacts in FZ3D resulted in 100 out of 105 total errors (95%) to be within the accepted error range of 20cm. Of the five total errors outside 20cm, one was obtained from the 75cm position and four from the 100cm position. 75% of the total errors were below 9.43cm from the 50cm position, 14.88cm from the 75cm position, and 17.39cm from the 100cm position. This could indicate that there is a positive correlation between the distance of the impact from the surfaces and total errors obtained. Based on results of previous literature and comparison to FARO Scene software, FZ3D is shown to have acceptable area of origin analysis tools. [ABSTRACT FROM AUTHOR]

This work characterizes fundamental features of static drip patterns simulated for forensic bloodstain pattern analysis. The purpose of this study was to determine if and how two independent variables, impact velocity and droplet number, influence the parent stain size, shape and satellite spatter distribution of drip patterns created with whole ovine blood. To do this, 500 drip patterns were created in a controlled environment at five varying impact velocities and ten different droplet numbers on a hard paper surface. Digital images of the dried patterns were processed and analyzed using Fiji (ImageJ). The data collected from each pattern support the hypotheses that drip patterns contain predictable and reproducible elements based on impact velocity and droplet number. Basic fluid dynamic principles demonstrate that the size of the parent stains, as well as the number and distribution of satellite stains increase with increasing Weber number. A decrease in the circularity of the parent stains was also noted. This study provides fundamental qualitative and quantitative data on observable elements of drip patterns that can be used practically by bloodstain pattern analysts for pattern identification and classification. [ABSTRACT FROM AUTHOR]

There are few reports of studies of impact spatter on textiles even though bloodstained textiles are found at many violent scenes. Impact spatter was deposited at 90° impact angle onto three knit fabrics of different yarn sizes and on paper. The resulting stain areas and number of stains were measured using ImageJ and compared with stains on paper using one‐factor ANOVA. The number of stains observed and their areas on the knit fabrics decreased as the yarn size increased. It was also found that blood that deposited on the fabric wicked only in the direction of the fibers at that location within the fabric which led to distorted stain shapes. Fewer observed impact spatter stains were found on cotton jersey knits for fabrics made with larger yarns than on paper. As the yarn size became smaller, the number of stains became the same as on paper. [ABSTRACT FROM AUTHOR]

Although the characteristics of cast‐off bloodstain patterns are well known, the physics of the mechanism by which they are created is poorly understood. The aim of this work was to describe the process by which blood droplets disengage from swinging objects. Cast‐off droplets were recorded using high‐speed digital video photography, and the resulting cast‐off patterns were analyzed to draw inferences about the trajectories of individual drops. Blood on the object's distal end formed ligaments, which subsequently disintegrated into droplets. Initial droplet trajectories were approximately tangential to the trajectory of the location on the object from which the droplet was released. The application of the laws of physics to the mechanism of cast‐off is discussed, and the process of drop formation is compared to that of passive drop formation. A technical description of cast‐off is proposed, and a diagram to aid investigators in interpreting cast‐off patterns at crime scenes is offered. [ABSTRACT FROM AUTHOR]

An investigation into the arm and body position required to obtain the blood pattern visible in the image of the Shroud of Turin was performed using a living volunteer. The two short rivulets on the back of the left hand of the Shroud are only consistent with a standing subject with arms at a ca 45° angle. This angle is different from that necessary for the forearm stains, which require nearly vertical arms for a standing subject. The BPA of blood visible on the frontal side of the chest (the lance wound) shows that the Shroud represents the bleeding in a realistic manner for a standing position while the stains at the back—of a supposed postmortem bleeding from the same wound for a supine corpse—are totally unrealistic. Simulation of bleeding from the nail wounds contacting wood surfaces yielded unclear results. [ABSTRACT FROM AUTHOR]

Abstract: A backspatter pattern results from blood drops that travel retrograde to an applied external force. Historically, an array of animals and nonhuman objects have been used to create and study backspatter patterns. In this study, backspatter patterns captured on foam core targets that were placed 45.72 cm (18 in) behind the impact site (occipital area of the skull) were produced by cranial gunshots to human cadavers that were reinfused with fresh defibrinated bovine blood. These patterns were compared to the backspatter patterns produced by shooting blood‐soaked sponges, a typical simulant used in controlled studies of backspatter pattern production and characteristics. The backspatter pattern produced by shooting an actual human head was found to be different than those of blood‐soaked sponges in the number of stains produced, the size and size range of the stains, and the stain dispersion patterns. [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]

This article describes a New Zealand forensic agency's contextual information management protocol for bloodstain pattern evidence examined in the laboratory. In an effort to create a protocol that would have minimal impact on current work-flow, while still effectively removing task-irrelevant contextual information, the protocol was designed following an in-depth consultation with management and forensic staff. The resulting design was for a protocol of independent-checking (i.e. blind peer-review ) where the checker's interpretation of the evidence is conducted in the absence of case information and the original examiner's notes or interpretation(s). At the conclusion of a ten-case trial period, there was widespread agreement that the protocol had minimal impact on the number of people required, the cost, or the time to complete an item examination. The agency is now looking to adopt the protocol into standard operating procedures and in some cases the protocol has been extended to cover other laboratory-based examinations (e.g. fabric damage, shoeprint examination, and physical fits). The protocol developed during this trial provides a useful example for agencies seeking to adopt contextual information management into their workflow. [ABSTRACT FROM AUTHOR]

This paper reports a case of a 72-year-old woman who was found dead in her bedroom with a 4 cm vertical stab wound in the abdomen. A bloodstained knife was found in the top drawer of her bedside table. The clothes worn by the victim showed no damage. A bloodstained vest and a sweater with frontal incisions were found far from the victim, in the bathroom and in the bedroom respectively. Several bloodstains were found in every room of the apartment. The evidence found during the forensic examination and, in particular, the Bloodstain Pattern Analysis, led the investigators to determine the manner of death, being consistent with a suicide with a long-lasting physical activity after self-stabbing. This report describes an unusual case of 'disguised suicide,' in which the victim tried to cover-up the suicide by changing her clothes and concealing the weapon, in the last minutes of her life. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis ( BPA) provides significant evidentiary value in crime scene interpretation and reconstruction. In this work, we develop a quantitative methodology using digital image analysis techniques to differentiate impact bloodstain patterns. The bloodstain patterns were digitally imaged and analyzed using image analysis algorithms. Our analysis of 72 unique bloodstain patterns, comprising more than 490,000 individual droplet stains, indicates that the mean drop size in a gunshot spatter pattern is at most 30% smaller than the mean drop stain size in blunt instrument patterns. In contrast, we demonstrate that the spatial distribution of the droplet stains-their density as a function of position in the pattern-significantly differs between gunshot and blunt instrument patterns, with densities as much as 400% larger for gunshot impacts. Thus, quantitative metrics involving the spatial distribution of droplet stains within a bloodstain pattern can be useful for objective differentiation between blunt instrument and gunshot bloodstain patterns. [ABSTRACT FROM AUTHOR]

There is a growing trend in forensic science to develop methods to make forensic pattern comparison tasks more objective. This has generally involved the application of suitable image-processing methods to provide numerical data for identification or comparison. This paper outlines a unique image-processing methodology that can be utilised by analysts to generate reliable pattern data that will assist them in forming objective conclusions about a pattern. A range of features were defined and extracted from a laboratory-generated impact spatter pattern. These features were based in part on bloodstain properties commonly used in the analysis of spatter bloodstain patterns. The values of these features were consistent with properties reported qualitatively for such patterns. The image-processing method developed shows considerable promise as a way to establish measurable discriminating pattern criteria that are lacking in current bloodstain pattern taxonomies. [ABSTRACT FROM AUTHOR]

Swipe and wipe are types of transfer patterns commonly encountered at bloodied scenes. So far, there have been little published data on the reliability of evaluating these patterns. In this study, 36 bloodstain patterns were randomly assigned to 12 analysts in three separate trials, and the analysts were required to evaluate the pattern type and directionality. The results revealed that correct classifications of patterns type were problematic, with an overall error rate of 32%. Wipes created from wet bloodstains were the most difficult to identify due to the absence of signs of alteration. The directionality of swipes made with a gloved finger had a 100% success rate; however, for swipes made with cloth, the analysts mistook the direction in nearly every case, which is of significant concern, considering these are common patterns at crime scenes. This study suggested there is a need for revising the current protocols for interpretation of these pattern types. [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.)

During a bloodstain pattern analysis, one of the essential tasks is to distinguish between different kinds of applied forces as well as to estimate their level of intensity. In this study, high-speed digital imaging has been used to analyze the formation of cast-off patterns generated by a simulated backswing with a blood-bearing object. For this purpose, 0.5 mL blood was applied evenly over the last 5 cm of a blade simulant. Bloodstains were created through the controlled acceleration of a backswing at different speed levels between 1.1 m/sec and 3.8 m/sec. The flight dynamics of blood droplets were captured with an Olympus® i-Speed 3 high-speed digital camera with a Nikon® AF Nikkor 50 mm f/1.8 D lens and analyzed using the Olympus i-Speed 3 Viewer software. The video analysis showed that, during the backswing, blood droplets would move toward the lower end of the knifepoint and would be tangentially thrown off. These droplets impacted on the horizontal surface according to the arc of the swing. An increase in velocity led to longer cast-off patterns with distinct morphological characteristics. Under laboratory conditions, bloodstain pattern analysis allows certain conclusions about the intensity of a backswing and provides instructions on the position of the offender. However, due to the number of unknown variables at a crime scene, such interpretation of cast-off patterns is extremely limited and should be performed with extreme caution. [ABSTRACT FROM AUTHOR]

The spreading dynamics of blood dripping onto hard surfaces is compared to two spreading models. Samples of human blood, porcine blood, and Millipore® water were dripped onto cardboard, foamcore, and glass surfaces in low velocity passive drip simulations. Final stain diameter, the total number of spines and scallops, and angle of impact were measured and analyzed. Spreading is best predicted by applying the concept of effective viscosity to the Scheller and Bousfield ( R2 = 0.91) and Roisman ( R2 = 0.89) spreading models. In the tested conditions, blood spreads with Newtonian tendencies; however, has quantifiable differences in stain appearance to Newtonian fluids like water. This is encouraging for the development of water-based fluids as synthetic blood substitutes ( SBSs). The work presents an assessment platform to quantify and score the performance of simple water-based fluids using final stain diameter (6 points) and number of spines and scallops (6 points) at six dripping heights between 20 and 120 cm. The angle of impact of a stain alone is not a sensitive measure of SBS performance, but stain formation scores the SBS's performance with another 1 point. Together these features generate a quantitative relative ranking system, of a maximum possible 13 points, that can be used to support the use of a particular fluid for the creation of a drip stain. The performance of twenty simple fluids in the simulated dripping assessment test is described. [ABSTRACT FROM AUTHOR]

This study was carried out in order to determine how different bullet calibers shot from different distances would affect blood spatter. Using two distinct firearms and varying distances, bullets were shot at a target in order to make blood spatter from different angles onto a tri-fold project board. The results illustrated that as the caliber of a bullet and the distance away from a target increase the area of blood spatter will increase and higher caliber bullets create more spatter because of their increased force. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis has become a field of specialization in Forensic sciences and plays an important role in the reconstruction of events at a crime scene. Research, books, and articles have been published on the analysis and interpretation of bloodstain patterns We present a case study of a road traffic accident in which bloodstain pattern analysis helped us to solve the discrepancy between reports produced by forensic examiners and by the forensic biology department. The case was of a 22-year-old man who died immediately and a 31- year-old woman who survived a road traffic accident. They were both found outside their overturned car and it was impossible to ascertain from initial observations which of the victims was driving the car at the time of the accident. An external examination of the man revealed multiple injuries, and the cause of his death was severe brain injury. The woman survived with a fracture of the forearm, dislocated clavicle bone, and other minor injuries. After initial examination of the car and based on the pattern of injuries the deceased received, forensic examiner concluded that the man was the driving the car at the time of accident. On the other hand, the forensic DNA analysis of bloodstains obtained from the driver's seat matched that of the woman, suggesting that she was the driver. This apparent discrepancy directed the forensic examiner to carry out a bloodstain pattern analysis on the driver's seat. The bloodstain pattern analysis helped resolve the discrepancy and enabled the investigators to identify the driver correctly. This case report emphasizes the importance of bloodstain pattern analysis in the reconstruction of cases involving road traffic accidents.

This study was designed to produce the first baseline measure of the reliability of bloodstain pattern classifications on fabric surfaces. Experienced bloodstain pattern analysts classified bloodstain patterns on pairs of trousers that represented three fabric substrates. Patterns also varied in type (impact, cast‐off, expiration, satellite stains from dripped blood, and transfer) and extent. In addition, case summaries that accompanied each pattern contained contextual cues that either supported the correct answer (i.e., positive bias), were misleading toward an incorrect answer (i.e., negative bias), or contained no directional information (i.e., neutral). Overall, 23% percent of the resulting classifications were erroneous. The majority (51%) of errors resulted from analysts misclassifying satellite stains from dripped blood. Relative to the neutral information, the positive‐bias information increased correct classifications and decreased erroneous classifications, and the negative‐bias information decreased correct classifications and increased erroneous classifications. The implications of these findings for BPA are discussed. [ABSTRACT FROM AUTHOR]

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]

This research uses high-speed video analysis of bloodstain impact events to investigate the influence of impact velocity, fluid depth and free-space on the characteristics of the mechanism. We focus on the changes in the crown growth over time. This work demonstrates qualitative differences in the impact mechanism under a range of impact conditions. These differences are further explained quantitatively as a function of measured crown width and height lengths over time. Fluid dynamic explanations of this growth are featured in the results and discussion. A comparison to water dynamics is reported. Our image analysis demonstrates that droplets are consistently formed at points which are different from the impactor/fluid interface and that this difference is fluid dependent. This fluid dependency demonstrates the importance of accurately modeling fluid dynamics of blood when designing and deploying blood substitutes in forensics applications. [ABSTRACT FROM AUTHOR]

This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non-absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed. [ABSTRACT FROM AUTHOR]

Strengthening education and training in the forensic sciences requires the implementation of new and innovative technologies into existing teaching strategies. Scientific research in the design and use of artificial substitutes can offer new and advantageous contributions to such initiatives. This article describes the relevant considerations and advantages to designing a forensic blood substitute for use in forensic education and training facilities. BPA training materials must ensure safety, reliability, feasibility, and value added. Each of these considerations is addressed with a particular focus on the educational benefits (value added) that a forensic blood substitute can offer. In particular, the visual affordances of the material designed for this study will be highlighted in terms of its educational benefits to the training of scientists. [ABSTRACT FROM PUBLISHER]

This article explores the integration of innovative technologies into forensic science training initiatives and their effect on student engagement and depth of learning. Novel situation-oriented teaching practices were researched and implemented with the goal of enhancing the quality of practitioner forensic science training. Specifically, a basic bloodstain pattern analysis course was designed to provide and test technological-pedagogical innovations. University student surveys suggest that a combination of technologies that disentangle the complications of a crime scene is a reliable, engaging and effective approach for detailed training in bloodstain pattern analysis. [ABSTRACT FROM PUBLISHER]

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]

A mechanical device that uses gravitational and spring compression forces to create spatter patterns of known impact velocities is presented and discussed. The custom-made device uses either two or four springs ( k1 = 267.8 N/m, k2 = 535.5 N/m) in parallel to create seventeen reproducible impact velocities between 2.1 and 4.0 m/s. The impactor is held at several known spring extensions using an electromagnet. Trigger inputs to the high-speed video camera allow the user to control the magnet's release while capturing video footage simultaneously. A polycarbonate base is used to allow for simultaneous monitoring of the side and bottom views of the impact event. Twenty-four patterns were created across the impact velocity range and analyzed using HemoSpat. Area of origin estimations fell within an acceptable range (Δ Xav = −5.5 ± 1.9 cm, Δ Yav = −2.6 ± 2.8 cm, Δ Zav = +5.5 ± 3.8 cm), supporting distribution analysis for the use in research or bloodstain pattern training. This work provides a framework for those interested in developing a robust impact device. [ABSTRACT FROM AUTHOR]

During Bloodstain Pattern Analysis (BPA), an analyst may encounter various sources of contextual information. Although contextual bias has emerged as a valid concern for the discipline, little is understood about how contextual information informs BPA. To address this issue, we asked 15 experienced bloodstain pattern analysts from New Zealand and Australia to think aloud as they classified bloodstain patterns from two homicide cases. Analysts could request items of contextual information, and were required to state how each item would inform their analysis. Pathology reports and additional photographs of the scene were the most commonly requested items of information. We coded analysts’ reasons for requesting contextual information—and the way in which they integrated this information—according to thematic analysis. We identified considerable variation in both of these variables, raising important questions about the role and necessity of contextual information in decisions about bloodstain pattern evidence. [ABSTRACT FROM AUTHOR]

The classification of bloodstain patterns has been identified as a challenging part of bloodstain pattern analysis due to the lack of a widely accepted and well-defined methodology and the ambiguity often associated with examining bloodstain patterns. The main aim of this study was to develop an objective, science-based method, for classifying bloodstain patterns, through the development of common language that could be used by BPA experts to describe the appearance of the pattern. This novel approach encourages a shift in the mindset of a BPA analyst by bringing them 'back to the basics' by treating components of a bloodstain pattern as discrete, observable and measurable units. One of the principal problems with current pattern classification methods is that pattern types are generally described in terms of the mechanism of pattern formation rather than grouping according to observable pattern characteristics. This study extends current BPA classification methodologies by developing and validating mechanism-free nomenclature that arises from observing and documenting the physical characteristics of bloodstain patterns. Following the grouping of bloodstain components on the basis of their physical characteristics, the formation evolution of these components is then investigated using concepts drawn from the fluid-dynamics of bloodstain pattern formation. This study offers a promising approach to distinguishing between different bloodstain pattern types through the use of visual aids in the form of colour maps, high-speed video and static digital images. [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.)

Blood spatter analysis is an important step for crime scene reconstruction. The presence of saliva in blood spatter could indicate expectorated blood which is difficult to distinguish from impact spatter. In this study, four saliva test methods (SALIgAE®, Phadebas® sheet, RSID™-Saliva kit, and starch gel diffusion) were compared to identify the best method for detecting expectorated blood spatter. The RSID™-Saliva kit showed the highest sensitivity even when saliva was mixed with blood, and was not inhibited by the presence of blood. The SALIgAE® test provided easy and rapid results, but the yellow color of a positive reaction was overwhelmed by the red color of the blood. The starch gel diffusion method and the Phadebas® sheet exhibited relatively low sensitivity and the assay took a long time. When using the RSID™-Saliva kit for identifying saliva in blood, results should be read within 10 min. [ABSTRACT FROM AUTHOR]

The point of origin of an impact pattern is important in establishing the chain of events in a bloodletting incident. In this study, the accuracy and reproducibility of the point of origin estimation using the FARO Scene software with the FARO Focus3D laser scanner was determined. Five impact patterns were created for each of three combinations of distances from the floor (z) and the front wall (x). Fifteen spatters were created using a custom impact rig, scanned using the laser scanner, photographed using a DSLR camera, and processed using the Scene software. Overall results gave a SD = 3.49 cm ( p < 0.0001) in the x-direction, SD = 1.14 cm ( p = 0.9291) in the y-direction, and SD = 9.08 cm ( p < 0.0115) in the z-direction. The technique performs within literature ranges of accepted accuracy and reproducibility and is comparable to results reported for other virtual stringing software. [ABSTRACT FROM AUTHOR]

In bloodstain pattern analysis, the blood droplet volume and surface impact velocity play an important role, and many related experimental studies have been carried out. If an appropriate computational fluid dynamics ( CFD) model that could solve bloodstain patterns, especially spine formation bloodstain patterns, can be obtained, the blood droplet volume and impact speeds at various crime scenes can be predicted more accurately. For this purpose, Flow-3D software using the volume-of-fluid method was applied to analyze the behavior of human blood droplets during an impact event, especially focusing on the viscous effect on splashing, which forms the spine which can be used to predict the impact velocity. To obtain a non-Newtonian viscosity model of blood for a computational fluid dynamic analysis, the venous blood samples of 163 people were tested using a hemorheology instrument. Among the venous blood samples of 163 people, 37 samples for which all blood test results were in a normal range were selected for the non-Newtonian viscosity modeling. From the CFD analysis, it could be concluded that a non-Newtonian viscosity model is more appropriate than a constant viscosity model for predicting splashing that forms the spine. The gradient of the non-Newtonian model at a high shear rate has more of an effect on spine formation than that at a low shear rate. The lowest viscosity with a high velocity at the outer front of the radiating flow plays an important role in forming the splashing pattern. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis to determine the wound-of-origin of bloodstains is problematic with nonspecific patterns. In this proof-of-concept study, the authors examined a molecular approach to correlate bloodstains with injuries using the rat as a model. Specifically, investigations were conducted on the rat brain marker, rno-miR-124-3p, with the QIAGEN miScript System and real-time PCR analysis. Rno-miR-124-3p was detected in brain homogenates diluted 100,000 times; in 3-week-old, room temperature stored, simulated brain-blood stains; and in bloodstains from head gunshot wounds collected with swabs and subsequently frozen for 9-18 months; however, rno-miR-124-3p was not detected in whole blood. Proof-of-principle was demonstrated by the ability to distinguish bloodstains from a gunshot wound to the head versus bloodstains from a gunshot wound to the chest, by the testing of otherwise identical bloodstains from the two patterns for the presence of the marker. The results suggest a viable approach to a longstanding problem in casework. [ABSTRACT FROM AUTHOR]

The volume of bloodstains found on crime scenes may help forensic investigators reconstruct the location and kinematics of bloodletting events, as stain size, volume, and impact velocity are related. Optical coherence tomography was used as a method to determine the volume and volume ratio of dried and fresh bloodstains on both glass and irregular surfaces or deposited with an impact velocity. The volume of blood drops deposited on smooth glass surfaces was measured within a deviation of 2%. This deviation increased for droplets on irregular surfaces or deposited with an impact velocity. The volume ratio of dried and fresh bloodstains was equal to 19-28% depending on the individual donor and on the use of an anticoagulant. Optical coherence tomography is a good method to determine the volume of fresh and dried bloodstains in laboratory conditions and allows accurate determination of the dry/fresh ratio. [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.)

Recent studies on bloodstains have focused on determining the time since deposition of bloodstains, which can provide useful temporal information to forensic investigations. This study is the first to use smartphone cameras in combination with a truly low-cost illumination system as a tool to estimate the age of bloodstains. Bloodstains were deposited on various substrates and photographed with a smartphone camera. Three smartphones (Samsung Galaxy S Plus, Apple iPhone 4, and Apple iPad 2) were compared. The environmental effects - temperature, humidity, light exposure, and anticoagulant - on the bloodstain age estimation process were explored. The color values from the digital images were extracted and correlated with time since deposition. Magenta had the highest correlation (R2 = 0.966) and was used in subsequent experiments. The Samsung Galaxy S Plus was the most suitable smartphone as its magenta decreased exponentially with increasing time and had highest repeatability (low variation within and between pictures). The quantifiable color change observed is consistent with well-established hemoglobin denaturation process. Using a statistical classification technique called Random ForestsTM, we could predict bloodstain age accurately up to 42 days with an error rate of 12%. Additionally, the age of forty blind stains were all correctly predicted, and 83% of mock casework samples were correctly classified. No within- and between-person variations were observed (p > 0.05), while smartphone camera, temperature, humidity, and substrate color influenced the age determination process in different ways. Our technique provides a cheap, rapid, easy-to-use, and truly portable alternative to more complicated analysis using specialized equipment, e.g. spectroscopy and HPLC. No training is necessary with our method, and we envision a smartphone application that could take user inputs of environmental factors and provide an accurate estimate of bloodstain age. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis ( BPA) involves the interpretation of distinct blood patterns found at crime scenes following a violent act. In this paper, we explored for the first time the effects of surface temperatures upon blood impacting a horizontal surface (steel) with its implications in BPA explored. Specific surface temperatures were explored over the range 24-250°C which relate to the four major boiling regimes of liquid media; natural convection, nucleate boiling, transition boiling, and film boiling, where a series of blood drops tests were performed at varying impact velocities. Blood was found to separate into its components at temperatures of 50°C+, displayed as temperature induced blood rings, where a single secondary and a series of further inner rings are exhibited. This consequently led to the development of a new constant [ABSTRACT FROM AUTHOR]

Raman spectroscopy has demonstrated remarkable capabilities in identifying blood in controlled laboratory conditions. However, substrate interference presents a significant challenge toward characterizing body fluid traces with Raman spectroscopy at a crime scene. Here, several possible solutions are explored, including the selection of laser excitation, isolating the signal of blood using spectral subtraction and using a favorable substrate for collection which minimizes interference. Simulated blood stain evidence was prepared and analyzed using a Raman microscope with variable laser capabilities. It is shown that the best approach for detecting blood depends on the nature of the substrate and the type of interference encountered. [ABSTRACT FROM AUTHOR]

Fly feces and regurgitation deposits may be mistaken for bloodstain patterns at a crime scene, potentially compromising event reconstruction and/or misdirecting police resources. In some instances, these artifacts contain sufficient human biological material to generate a full DNA profile, sometimes 2 years after deposition. Clearly, it is important that investigators can make the distinction between artifacts and bloodstains. This study examined 6645 artifacts deposited on a smooth, nonporous surface after Lucilia cuprina were fed human blood. Artifacts were also compared with bloodstains on a variety of other surfaces. Both similarities and differences were found between artifacts and bloodstains, highlighting the need for an identification system to assist personnel with little training in bloodstain pattern analysis. The morphology of the artifacts has been described so that these deposits may be more clearly distinguished from bloodstains, targeted by crime scene personnel as potential sources of human DNA, and/or identified as potential evidence contaminants. Flowcharts have been devised to facilitate the analysis. [ABSTRACT FROM AUTHOR]

When it comes to firearm fatalities, the main goal of forensic analysis is to distinguish firearm suicides from homicides and accidents. Apart from the location of the entrance wound, wound path trajectory and gunshot residue, blood stain pattern analysis of gunshot-related backspatter on the hands of the victim can be an essential tool not only to determine which hand was holding the firearm, but also to reconstruct the position from which a weapon was fired. We present a case of a 90-year-old man, who was found dead in his house. Because of unclear circumstances and an unusual position of the deceased with a gunshot entrance wound to the right temporal region and a firearm found on the left side of his body, an autopsy was performed. Due to the unusual bloodspatter stains on the hands and the firearm, it was possible to deduce the position and orientation of the hands and the firearm of the deceased. We could reconstruct that the man held the weapon in his right hand, using the left hand to stabilise the firearm and the right thumb to pull the trigger. A contact shot to the right temple led to central regulatory failure due to extensive brain injury. The manner of death was concluded to be a suicide. [ABSTRACT FROM AUTHOR]