The Development and Application of Random Match Probabilities to Firearm and Toolmark Identification

The field of firearms and toolmark analysis has encountered deep scrutiny of late, stemming from a handful of voices, primarily in the law and statistical communities. While strong scrutiny is a healthy and necessary part of any scientific endeavor, much of the current criticism leveled at firearm and toolmark analysis is, at best, misinformed and, at worst, punditry. One of the most persistent criticisms stems from the view that as the field lacks quantified random match probability data (or at least a firm statistical model) with which to calculate the probability of a false match, all expert testimony concerning firearm and toolmark identification or source attribution is unreliable and should be ruled inadmissible. However, this critique does not stem from the hard work of actually obtaining data and performing the scientific research required to support or reject current findings in the literature. Although there are sound reasons (described herein) why there is currently no unifying probabilistic model for the comparison of striated and impressed toolmarks as there is in the field of forensic DNA profiling, much statistical research has been, and continues to be, done to aid the criminal justice system. This research has thus far shown that error rate estimates for the field are very low, especially when compared to other forms of judicial error. The first purpose of this paper is to point out the logical fallacies in the arguments of a small group of pundits, who advocate a particular viewpoint but cloak it as fact and research. The second purpose is to give a balanced review of the literature regarding random match probability models and statistical applications that have been carried out in forensic firearm and toolmark analysis.     

司法鉴定错误损害赔偿诉讼的法理基础与实证考察

鉴定机构提供司法鉴定时,发生鉴定错误在所难免.诉讼当事人因司法鉴定错误发生损害,对司法鉴定机构提起损害赔偿之诉时,实践中往往不能得到法院的支持.诉讼当事人对司法鉴定机构主张损害赔偿不仅存在侵权责任请求权基础,更存在违约责任请求权基础,发生请求权基础竞合.诉讼当事人对司法鉴定机构提起损害赔偿之诉,应以司法鉴定错误得到确认为前提.受司法既判力的约束,只能在对原案件事实的审理程序中重新进行司法鉴定.因此,诉讼当事人对司法鉴定机构提起损害赔偿之诉在程序上受到严格限制,并以此决定其可主张的损害赔偿范围.     

Medicolegal assessment of blood transfusion errors--an interdisciplinary challenge

Given a current total incidence of erroneously administered blood transfusions of 1:12,000-1:36,000 (AB0 incompatible 1:38,000), the percentage of lethal outcomes ranges between 2 and 5%; i.e. the sole fact of an erroneous transfusion does not mandatorily result in a causal connection with lethal outcome, which can give rise to problems in the medicolegal assessment. We report on the conception and results of a novel interdisciplinary approach to assess the lethal significance of blood transfusion errors. Besides autopsy, histological investigation and immunohistochemical detection of AB0 incompatible foreign red blood cells in autopsy specimens, transfusion medicine investigations offer the opportunity to assess several immunohaematologic features. We assessed the immunohaematologic gel card ("microcolumn") technique for suitability in the forensic assessment of an AB0 incompatible transfusion incident in a septic patient, who had had no history of previous blood transfusions, with lethal outcome. After such an erroneous transfusion had been simulated in vitro, pre-transfusion and cadaver patient blood samples (p.m. interval: 3 days) were analysed. Amongst other things, IgG-loaded erythrocytes were detected in pre- and post-transfusion samples; the presence of irregular antibodies directed against blood group antigens and anti-A or anti-B isoagglutinins, respectively, especially in the pre-transfusion sample was ruled out. Besides the demonstration of AB0 incompatible red blood cells in the cadaver blood sample, blood group incompatibilities other than AB0 were excluded. With regard to the cause of death, in synopsis with autopsy findings and clinical symptoms, the results did not allow for a final discrimination between the impact of the pre-existing septic inflammatory response syndrome and sepsis, respectively, and potential lethal effects of a (haemolytic) transfusion reaction. Besides pre- and post-transfusion compatibility testing in clinical transfusion medicine as required by German National Guidelines, the reported immunohaematologic investigations offer an important supportive tool for the forensic assessment of lethal erroneous transfusions and investigation of blood samples of survivors of transfusion incidents as well. Besides established morphological techniques, they allow for a certain evaluation of the pathophysiological impact of transfusion incidents as well as a diversified assessment of immunohaematologic features beyond the AB0 system.     

Investigation of Reproducibility and Error Associated with qPCR Methods using Quantifiler® Duo DNA Quantification Kit*

Abstract: Reproducibility of quantitative PCR results is dependent on the generation of consistent calibration curves via accurate volume transfers and instrument performance. A review of 14 standard curves, using two different QuantDuo^® standard DNA lots, showed variability of cycle threshold values between assays were larger than those of the Internal PCR Control (IPC). This prompted a set of experiments designed to determine the source of variability. Results showed that error introduced during DNA addition to the plate resulted in little variation. A comparison of seven independent series demonstrated cycle threshold variation between dilutions was larger than the variation expected from repeated samples. Modeling the influence of pipette errors on dilution series accuracy indicated that a more rigorous approach to external calibration curve production is required and showed that improvement in calibration curve stability is expected if the pipette conditions are carefully chosen and/or a single validated curve is utilized as the calibrator.     

车辆上脱落细胞STR检验

目的对汽车方向盘及变速杆把手上的皮肤脱落细胞进行STR检验研究。方法用EZ-tape采集车辆方向盘及变速杆上的脱落细胞,Chelex-100法与磁珠法结合提取DNA,延长保温时间。定量后调整PCR反应体系,适当增加PCR循环数,增加PCR产物量及延长进样时间进行电泳检测,使用GeneMapperIDV3.2软件进行STR分型。同时,对比使用多重置换扩增技术对提取的DNA进行全基因组扩增。结果对33份车辆方向盘和变速杆上脱落细胞的检测,其中19份检出全部基因座的基因分型结果,9份检出部分基因型,5份未检出DNA分型结果。而利用多重置换扩增技术未获得满意图谱。结论本研究建立的脱落细胞收集、DNA提取、PCR扩增及检测方法适合于车辆上脱落细胞的检验,其结果优于使用多重置换扩增技术获得的分型。     

车辆上脱落细胞STR检验

目的对汽车方向盘及变速杆把手上的皮肤脱落细胞进行STR检验研究。方法用EZ-tape采集车辆方向盘及变速杆上的脱落细胞,Chelex-100法与磁珠法结合提取DNA,延长保温时间。定量后调整PCR反应体系,适当增加PCR循环数,增加PCR产物量及延长进样时间进行电泳检测,使用GeneMapperIDV3.2软件进行STR分型。同时,对比使用多重置换扩增技术对提取的DNA进行全基因组扩增。结果对33份车辆方向盘和变速杆上脱落细胞的检测,其中19份检出全部基因座的基因分型结果,9份检出部分基因型,5份未检出DNA分型结果。而利用多重置换扩增技术未获得满意图谱。结论本研究建立的脱落细胞收集、DNA提取、PCR扩增及检测方法适合于车辆上脱落细胞的检验,其结果优于使用多重置换扩增技术获得的分型。     

侦查中影响测谎结论准确性的因素

测谎技术是当前在侦查实践中经常使用的一种技术手段,由于受主观和客观因素的影响,使得测谎结论出现偏差。本文通过对测谎技术存在误差的客观性、常见误差的分析及衡平的探究,进而对影响准确性的因素进行剖析,总结性的得出测谎准确度的使用公式。     

A Perspective on Errors,Bias, and Interpretation in the Forensic Sciences and Direction for Continuing Advancement*

Abstract: The forensic sciences are under review more so than ever before. Such review is necessary and healthy and should be a continuous process. It identifies areas for improvement in quality practices and services. The issues surrounding error, i.e., measurement error, human error, contextual bias, and confirmatory bias, and interpretation are discussed. Infrastructure is already in place to support reliability. However, more definition and clarity of terms and interpretation would facilitate communication and understanding. Material improvement across the disciplines should be sought through national programs in education and training, focused on science, the scientific method, statistics, and ethics. To provide direction for advancing the forensic sciences a list of recommendations ranging from further documentation to new research and validation to education and to accreditation is provided for consideration. The list is a starting point for discussion that could foster further thought and input in developing an overarching strategic plan for enhancing the forensic sciences.     

Eyewitness Memory in Context: Toward a Taxonomy of Eyewitness Error

Although eyewitness memory and identification have captured substantial research interest in the past decades, an understanding of the types and prevalence of errors typically made by eyewitnesses is lacking. The purpose of the present research was to begin the development of a taxonomy of eyewitness error, employing standardized stimuli and established techniques. Respondents were exposed to a crime scene modeled on SWAT-training scenarios for systematically varied exposure times, and were then asked to describe what they had seen. The stimuli and questions employed were prepared with the aid of senior police field training officers. As anticipated, eyewitness performance in general was subject to a variety of inaccuracies. Physical errors, such as mistakes in the clothing or physical characteristics of the perpetrator, or in details of the environmental context, predominated. However, other less-expected errors were also observed: in relatively low numbers of cases, witnesses inferred emotional states or intent on the part of the perpetrator or victim. Some contributed wholly artificial backstories, reported the future actions of the perpetrator or victim as memories, or even inserted themselves into the scene. The pattern of results was shown to interact with exposure time, gender of the perpetrator, and the presence or absence of weapons in the scene. The results of this study are consistent with reconfigurative theory dating to Bartlett (1932), with subsequent research, and with more recent work under the aegis of Gestalt/Feature-Intensive Processing theory. These findings provide information on types and prevalence of eyewitness error which should prove useful in investigative and courtroom settings.     

反劫持谈判战术误区(上)

警方谈判者在实际的反劫持谈判中,不能主动和有效地控制谈判发展的方向,是警控谈判中的大忌,是谈判者无力适应、无法发挥应有的谈判水平的最直观的表现．是预示着本次反劫持谈判可能发生失利的一种兆头。