Search

Bloodstain pattern analysis (BPA) has proven to be a useful tool in forensic and criminal investigations for quite some time. Traditionally, documenting a crime scene for a bloodletting event was completed using manual techniques, physical strings, and a tape measure. In more recent years, laser scanners and 3D software programs have become a preferred method to capture accurate data that improves the validity and reliability of BPA. The initial cost of laser scanning equipment is relatively high, rendering these systems inaccessible to some police and smaller agencies. Recon-3D is a newly developed iPhone application that utilizes the iPhone LiDAR sensor in combination with video data to create 3D point clouds of crime scenes. To assess the viability of Recon-3D for area of origin analysis, two tests were performed. One was a series of bloodstain impacts which were analyzed in FARO Zone 3D software, while the second was a series of 6 repeated Recon-3D scans of two 90-degree walls which was then compared to the FARO Focus S350 scanner using CloudCompare software. A total of eight impact patterns were made at three different distances from a wall. The area of origin was measured and compared to the known location of the blood source. The average total 3D error for the area of origin set at 25, 50, and 100 cm from two perpendicular walls was found to be 6.04, 15.16, and 36.59 cm, respectively. These results are similar to past studies where programs such as HemoSpat have been used. The results of the point cloud comparison show that on average, 95% of the points from Recon-3D fall below a threshold of 3.6 mm when compared to a FARO Focus S350 laser scanner. Thus, the results of this test suggest that Recon-3D is an accurate and affordable scanning application for bloodstain patterns at crime scenes and the data provide acceptable results for area of origin analysis in BPA programs which accept laser scanner data. [ABSTRACT FROM AUTHOR]

In bloodstain pattern analysis (BPA), a field of forensic science, there has been active discussion on the estimation of the area of origin of impact spatter. However, there is no established methodology to quantitatively analyze the area of origin of a swing cast-off pattern. To quantitatively analyze the methodology of previous research on estimation of area of origin, a device for generating uniform swing cast-off patterns was produced. Using artificial blood, 10 swing cast-off patterns were generated on porous paper; in each, 10 blood drops were selected for the calculation of the impact angle. Hemospat software was used for individual bloodstain analysis, and an open source code was used for estimation of area of origin. Under the same conditions, an additional 10 swing cast-off patterns were generated, and quantitative analysis was performed using trigonometric functions and an adjustment formula that minimized errors in calculating the impact angle. The adjustment formula was corrected to calculate the impact angle for the bloodstains on the porous surface. As uncertainty decreases, the error increases, and the point at which both uncertainty and error can be minimized is calculated as 75%. The existing formula included the trajectory in the estimated likelihood range in 75% of samples. When the adjustment formula was applied, the accuracy was improved, with the trajectory included in the area with a 90% likelihood. [ABSTRACT FROM AUTHOR]

There is an apparent paradox that the likelihood ratio (LR) approach is an appropriate measure of the weight of evidence when forensic findings have to be evaluated in court, while it is typically not used by bloodstain pattern analysis (BPA) experts. This commentary evaluates how the scope and methods of BPA relate to several types of evaluative propositions and methods to which LRs are applicable. As a result of this evaluation, we show how specificities in scope (BPA being about activities rather than source identification), gaps in the underlying science base, and the reliance on a wide range of methods render the use of LRs in BPA more complex than in some other forensic disciplines. Three directions are identified for BPA research and training, which would facilitate and widen the use of LRs: research in the underlying physics; the development of a culture of data sharing; and the development of training material on the required statistical background. An example of how recent fluid dynamics research in BPA can lead to the use of LR is provided. We conclude that an LR framework is fully applicable to BPA, provided methodic efforts and significant developments occur along the three outlined directions. [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]

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]

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]

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]

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 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]

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]

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]

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]

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]

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]

Bloodstain photography is important in forensic applications, especially for bloodstain pattern analysis. This study compares the enhancement effect of bloodstain photography using three different types of light source: fluorescent white light, near-ultraviolet (UV) light-emitting diode (LED) light, and 410 nm LED light. Randomized complete block designs were implemented to identify the lighting that would statistically produce the best enhancement results for bloodstains on different types of surfaces. Bloodstain samples were prepared on white cotton, brown carpet, tar road, and wood. These samples were photographed in darkroom conditions using a Canon EOS 50D digital SLR camera, with Canon EFS 60 mm f/2.8 Macro USM lens. Two-way analysis of variance and Fisher's least significant difference test were used to analyze the contrast of the images. The statistical analysis showed that 410 nm light is the best among the tested lights for enhancing bloodstains on the tested surfaces, where the contrast of bloodstain to background was the highest. [ABSTRACT FROM AUTHOR]

The analysis of bloodstain patterns can assist investigators in understanding the circumstances surrounding a violent crime. Bloodstains are routinely subjected to pattern analysis, which is inherently dependent upon the ability of the examiner to locate and visualize bloodstain patterns on items of evidence. Often, the ability to properly visualize bloodstain patterns is challenging, especially when the stain patterns occur on dark and/or patterned substrates. In this study, preliminary research was performed to better understand how near-infrared reflectance hyperspectral imaging (HSI) could be used to observe bloodstain patterns on commonly encountered black fabrics. The ability of HSI to visualize latent bloodstains on several commonly encountered substrates is demonstrated. The images acquired through HSI are of sufficient quality to allow for differentiation between stains produced from an impact mechanism or a transfer mechanism. This study also serves as a proof of concept in the differentiation of multiple staining materials. Because of its ability to generate spectral data, the data provide a preliminary separation of stains where more than one type of stain existed. [ABSTRACT FROM AUTHOR]

Gunshot backspatter comprises biological material expelled backward through bullet entry holes. Crime scene investigators analyze backspatter patterns to infer wounding circumstances. An understanding of the mechanism of backspatter generation, and the relationship between spatter patterns and bullet and tissue characteristics, would enhance the predictive value of such analysis. We examined soft-tissue ballistic wounding responses to determine the underlying components and how these might be relevant to the generation of backspatter. We identified five mechanistic components to ballistic wounding (elastic, viscous, crushing, cutting, and thermal), each related to mechanical disciplines (respectively, solid mechanics, fluid mechanics, fracture mechanics, rheology, and thermodynamics). We identified potential roles for these five components in backspatter formation and provide a scenario whereby a sequence of events incorporating these components could lead to backspatter generation and expulsion. This research provides a framework for the mathematical representation, and subsequent computational predictive modeling, of backspatter generation and pattern formation. [ABSTRACT FROM AUTHOR]

In bloodstain pattern analysis, it is important to know the point of origin (PO) of an impact pattern. This point can be estimated by means of the stringing method, the tangent method, or by commercially available computer programs. In this study, the accuracy of two computer programs was investigated under different conditions. Impact patterns were created by means of a modified mouse trap, and subsequently the PO was calculated. By examining the characteristics of single bloodstains, the influence on the deviation could be determined. To improve the estimation of the PO, it is important to select bloodstains that lie close to the presumable location of the blood source, that are large (width >1.5 mm) and that show an elliptical form. If possible, bloodstains from different walls should be taken into account. Our recommendations may improve the PO determination of impact patterns. [ABSTRACT FROM AUTHOR]

An experiment was designed to explore the underlying mechanisms of blood disintegration and its subsequent effect on area of origin (AO) calculations. Blood spatter patterns were created through the controlled application of pressurized air (20-80 kPa) for 0.1 msec onto suspended blood droplets (2.7-3.2 mm diameter). The resulting disintegration process was captured using high-speed photography. Straight-line triangulation resulted in a 50% height overestimation, whereas using the lowest calculated height for each spatter pattern reduced this error to 8%. Incorporation of projectile motion resulted in a 28% height underestimation. The AO xy-coordinate was found to be very accurate with a maximum offset of only 4 mm, while AO size calculations were found to be two- to fivefold greater than expected. Subsequently, reverse triangulation analysis revealed the rotational offset for 26% of stains could not be attributed to measurement error, suggesting that some portion of error is inherent in the disintegration process. [ABSTRACT FROM AUTHOR]

Bloodstain pattern analysis can be critical to accurate crime scene reconstruction. However, bloodstain patterns can be altered in the presence of insects and can confound crime scene reconstruction. To address this problem, we conducted a series of controlled laboratory experiments to investigate the effect of Lucilia sericata (Meigen) on impact bloodstains and pooled bloodstains in association with three combinations of common surfaces (linoleum/painted drywall, wood floor/wallpaper, and carpet/wood paneling). L. sericata fed from the pooled bloodstains and added insect stains through regurgitation and defecation of consumed blood. L. sericata formed defecatory trails of insect stains that indicated directionality. Defecatory stains fluoresced when viewed at 465 nm with an orange filter. These observations differed from Calliphora vicina insect stains because feeding on blood spatter was not observed and trails of insect stains were formed by L. sericata. The fluorescence of defecatory stains can be used as a method to detect insect stains and discriminate them from real bloodstains. [ABSTRACT FROM AUTHOR]

Droplets of pig’s blood were dropped onto paper at different angles to the horizontal to produce blood stains. Impact velocities varied from 1.82 to 5.76 m/sec, drop size from 3.7 to 5.0 mm in diameter, and the surface sloped at angles between 22.7° and 90° to the horizontal. From the data a single equation relating stain size to drop size and velocity for all impact angles was produced; ab = 111.74 (Re1/2We1/4)0.75 Do Do + 0.00084 with R2 = 0.88, where a is the stain width, b the stain length, Re the Reynolds number, and We the Weber number. A second equation related the number of spines, N, to drop size, velocity, and surface slope for all impact angles as N = 0.76 We0.5 sin3θ with R2 = 0.9, where θ is the impact angle. Combining these equations the impact velocity can be determined and hence the position of the stain’s source. [ABSTRACT FROM AUTHOR]

In a previous study, mechanical engineering models were utilized to deduce impact velocity and droplet volume of circular bloodstains by measuring stain diameter and counting spines radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate the accuracy of this technique, using an applied, crime scene methodology. Calculations from bloodstains produced on paper, drywall, and wood were used to derive surface-specific equations to predict 39 unknown mock crime scene bloodstains created over a range of impact velocities (2.2–5.7 m/sec) and droplet volumes (12–45 μL). Strong correlations were found between expected and observed results, with correlation coefficients ranging between 0.83 and 0.99. The 95% confidence limit associated with predictions of impact velocity and droplet volume was calculated for paper (0.28 m/sec, 1.7 μL), drywall (0.37 m/sec, 1.7 μL), and wood (0.65 m/sec, 5.2 μL). [ABSTRACT FROM AUTHOR]

Presents a study to determine the diameter and velocity of blood drops falling on a surface by measuring the bloodstains they produced and counting the number of radial spines projecting from them. Formation of bloodstains by releasing drops of pig blood with a range of diameters and impact velocities, onto four different flat surfaces with varying roughness; Use of high-speed photography to record impact dynamics; Presentation of equation that explicitly relate drop diameter and impact velocity to measurements of stain diameter and number of spines.

This study investigated whether routinely used forensic tests can distinguish 3-day-old or 2-week-old fly artifacts, produced after feeding on human blood, semen, or saliva, from the biological fluid. Hemastix®, Hemident™, and Hemascein™ were unable to distinguish blood from artifacts. Hemastix® returned false positives from negative controls. ABAcard® Hematrace® and Hexagon OBTI could distinguish blood from 3-day-old artifacts, but not 2-week-old artifacts. Phadebas® and SALIg AE® were unable to distinguish saliva from artifacts. RSID™-Saliva was able to distinguish saliva from 3-day-old artifacts, but not 2-week-old artifacts. Semen tests Seminal Acid Phosphatase, RSID™-Semen, and ABAcard® p30 were all able to distinguish semen from 3-day-old artifacts, but not 2-week-old artifacts. The tests investigated cannot be relied upon to distinguish artifacts from biological fluids. However, if an artifact is identified by its morphology, a positive result may indicate which biological fluid the fly consumed, and this knowledge may prove useful for investigators searching for DNA. [ABSTRACT FROM AUTHOR]

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]

The article focuses on the contextual information management in bloodstain pattern analysis. Topics discussed include use of contextual information management in forensic examinations; analyzing relationship between pattern characteristics and their causal event; and use of characteristic-based observations for the same.