The Reliability of Pattern Classification in Bloodstain Pattern Analysis—PART 2: Bloodstain Patterns on Fabric Surfaces,

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.     

The Reliability of Pattern Classification in Bloodstain Pattern Analysis,Part 1: Bloodstain Patterns on Rigid Non‐absorbent Surfaces

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.     

垂直抛甩状血迹形态的模拟观察

目的观察不同类型打击工具的垂直抛甩状血迹形态。方法选择常见的菜刀、匕首、方锤、铁管作为打击工具。用沾新鲜鸡血5 m L的工具自上而下进行垂直抛甩,对距离垂直墙壁30 cm处形成的血迹形态进行测量分析,通过对抛甩血迹的整体分布特征(跨度、宽度、密度)、起始血迹的形态特征(长度、宽度、接触角度)进行分析。结果匕首形成抛甩血迹的分布跨度最小(P0.05);在整体分布宽度上,菜刀最小(P0.05);在整体分布密度上,除菜刀与方锤之间差异无统计学意义,其他工具两两之间差异均有统计学意义(P0.05)。方锤较其他三种工具在起始血迹点长度上最长(P0.05);菜刀与方锤、匕首与方锤在起始血迹点宽度上差异有统计学意义(P0.05)。结论每一类型的打击工具所形成的垂直抛甩血迹形态具有一定的特征,可用于命案现场推断打击工具的类型。     

Preliminary Study on the Effect of Heated Surfaces Upon Bloodstain Pattern Analysis

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 expressing the decrease in spread factor (D_s/D_o) at the secondary ring.     

Bloodstain pattern analysis & Bayes: A case report

The findings from a bloodstain pattern analysis (BPA) may assist in formulating or falsifying scenarios that are considered in the investigative stages of a criminal investigation. When a case proceeds to trial the bloodstain pattern expert may be asked about the relevance of their findings given scenarios that are proposed by the prosecution and defense counsel. Such opinions provided by an expert are highly relevant to police investigation or legal proceedings, but the reasoning behind the opinion or implicit assumptions made by the expert may not be transparent.A proper framework for the evaluation of forensic findings has been developed since the late twentieth century, based on the hierarchy of propositions, Bayesian reasoning and a model for case assessment and interpretation. This framework, when implemented in casework, mitigates some of the risks of cognitive biases, and makes the reasoning and scientific basis for the opinion transparent. This framework is broadly used across forensic science disciplines. In this paper we describe its application to the field of BPA using a case example from the Netherlands Forensic Institute (NFI).     

Improved Area of Origin Estimation for Bloodstain Pattern Analysis Using 3D Scanning

An important component of crime scene reconstruction is bloodstain pattern analysis (BPA). Where BPA concerns impact patterns, estimating the area of origin is critical information for scene reconstruction. Traditionally, this is achieved by measuring individual bloodstains and performing trigonometric calculations; however, 3D scanning has been proposed as a viable alternative for overcoming logistical and practical concerns with the manual method. Therefore, this project aimed to establish whether the FARO Focus 3D scanner and FARO Zone 3D software can improve the accuracy of area of origin estimates relative to the manual method. We created a series of eight bloodstain impact patterns and performed paired analysis using the two methods to estimate areas of origin for each pattern. Our data suggested that FARO-derived estimates were generally more accurate than using the manual method. FARO-estimated heights of origin areas were generally closer to the true distance. Both methods underestimated the distance from the wall for most patterns originating 150mm or greater from the wall, but overestimated distances for patterns originating closer to the wall. The degree to which distances were underestimated increased significantly the further the blood source was from the wall and was greater for FARO-derived estimates. The results of this research contribute to the validation of these instruments for operational implementation for BPA and should be considered alongside the practical benefits of 3D scanning relative to manual methods. Further, 3D scanning can provide reliable BPA reconstruction documentation for technical review and court presentation.     

The Reliability of Swipe/Wipe Classification and Directionality Determination Methods in Bloodstain Pattern Analysis

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.     

论刑事证据的客观真实

对我国刑事诉讼中关于客观真实的证明标准,从理论和实践的结合上及与持不同观点者的辨析上,进行科学总结,并对此标准在运用中的利与弊进行剖析.着重从刑事证据本质特征及司法实践适用中的问题等方面,对客观真实的证明标准展开深入论证,以期对我国刑事证据制度的立法有所裨益.     

Approaches to Gender and the Law: Research and Applications

Three paradigms for gender research are reviewed, illustrated by examples from employment discrimination law to highlight issues in research on gender and the law. Next, an agenda for research on gender, social science, and the law is outlined, and the five articles in this special issue are reviewed in terms of that agenda. Finally, research ideas for the future and practical applications of the research presented in the five articles are considered, specifically, the use of the reasonable woman standard and expert testimony in sexual harassment cases, and the influence of sex roles and sex stereotypes in producing gender effects.