A mixed DNA profile controversy revisited

Semaan et al. (J Forensic Res, 2020, 11, 453) discuss a mock case “where eight different individuals [P₁ through P₈] could not be excluded in a mixed DNA analysis. Even though … expert DNA mixture analysis software was used.” Two of these are the true donors. The LRs reported are incorrect due to the incorrect entry of propositions into LRmix Studio. This forced the software to account for most of the alleles as drop-in, resulting in LRs 60–70 orders of magnitude larger than expected. P₁, P₂, P₄, P₅, and P₈ can be manually excluded using peak heights. This has relevance when using LRmix which does not use peak heights. We extend the work using the same two reference genotypes who were the true contributors as Semaan et al. (J Forensic Res, 2020, 11, 453). We simulate three two-donor mixtures with peak heights using these two genotypes and analyze using STRmix?. For the simulated 1:1 mixture, one of the non-donors’ LRs supported him being a contributor when no conditioning was used. When considered in combination with any other potential donors (i.e., with conditioning), this non-donor was correctly eliminated. For the 3:1 mixture, all results correctly supported that the non-donors were not contributors. The low-template 4:1 mixture LRs with no conditioning showed support for all eight profiles as donors. However, the results from pair-wise conditioning showed that only the two ground truth donors had LRs supporting that they were contributors to the mixture. We recommend the use of peak heights and conditioning profiles, as this allows better sensitivity and specificity even when the persons share many alleles.     

Observer determination of the make,model, and year of questioned vehicles

Often, criminal acts involving a vehicle are caught on digital video surveillance systems. While potentially useful for an investigation, the recording conditions are typically less than optimal for the extraction of key information for the identification of the perpetrator, such as a license plate. Providing the make, model and year of a questioned vehicle is a common request for examiners, to narrow the field of potential suspect vehicles. This study seeks to compare the performance of a nonpeer-reviewed make, model, and year determination between two separate groups, specifically, trained forensic image examiners and nontrained individuals. Results show that even with varied image capture conditions and quality, the trained forensic image examiners more correctly and completely identified the test group of questioned vehicles make, model, and year.     

基层派出所视频侦查体系构建实证研究

视频侦查已成为公安机关重要的刑侦基础性工作。目前省、市、县、所四级公安视频侦查体系基本建成,而作为基层一线的“所级”视频侦查体系,实践中没有受到足够的重视。应强化派出所层级的视频侦查体系建设,同时,合理协调全社会视频监控系统建设的系统推进,以提升视频侦查工作实战效能。     

What do forensic analysts consider relevant to their decision making?

In response to research demonstrating that irrelevant contextual information can bias forensic science analyses, authorities have increasingly urged laboratories to limit analysts' access to irrelevant and potentially biasing information (Dror and Cole (2010) [3]; National Academy of Sciences (2009) [18]; President's Council of Advisors on Science and Technology (2016) [22]; UK Forensic Science Regulator (2015) [26]). However, a great challenge in implementing this reform is determining which information is task-relevant and which is task-irrelevant. In the current study, we surveyed 183 forensic analysts to examine what they consider relevant versus irrelevant in their forensic analyses. Results revealed that analysts generally do not regard information regarding the suspect or victim as essential to their analytic tasks. However, there was significant variability among analysts within and between disciplines. Findings suggest that forensic science disciplines need to agree on what they regard as task-relevant before context management procedures can be properly implemented. The lack of consensus about what is relevant information not only leaves room for biasing information, but also reveals foundational gaps in what analysts consider crucial in forensic decision making.     

法医学尸体检验职业防护指南(建议稿)

法医工作者的职业暴露风险极大,案件现场及尸体上的有毒有害物质、高致病性微生物以及利器、骨折等因素均可能给法医带来身心伤害甚至生命危险。随着经济社会发展,法医的工作环境已经较过去显著改善,但是针对个人防护的重视程度仍需提高。近年来公共卫生事件频发,给法医职业防护带来新的挑战,迫切需要借鉴生物安全领域的先进技术和防护理念,以满足新形势下法医工作的需要。本指南立足当前法医职业防护的实际需求,从暴露风险、防护分级、应急处置等角度阐述,希望能为制定法医职业防护相关标准提供参考,以指导法医工作者开展个人防护工作,为提升法医职业化水平和身心健康提供帮助。     

大鼠急性心肌缺血早期内皮素的免疫组化染色观察

目的　探讨实验性大鼠心肌缺血后内皮素在心肌组织内的表达变化。方法　运用免疫组化技术 (SABC法 ) ,对分别经过单纯缝线结扎、药物、脂质饮食预处理后结扎及假结扎处理的 5组 60只实验大鼠 ,在冠脉左前降支结扎后的不同时间点 ,观察心肌组织的内皮素表达情况。结果　阳性组各个分组的大鼠在心肌缺血早期均出现了内皮素的阳性表达 ,且经过预处理、存在慢性心肌缺血倾向的大鼠在更短的时间内出现了阳性染色 ;而假结扎对照组未见明显的阳性染色。结论　内皮素免疫组化检测可作为早期心肌缺血的病理诊断指标之一 ,并可为心性猝死 (SCD)的诊断提供形态学依据。     

应用硅珠法提取陈旧骨骼DNA

骨骼相对于人体其他的组织脏器腐败降解慢,是进行高度腐败及白骨化样本DNA检验的唯一检材。但骨骼DNA的提取比较困难,本文运用传统的硅珠法提取骨骼DNA取得了很好的效果。1材料与方法1.1样本1~4年水浸泡、土埋的股骨、肱骨等样本,来自本实验室日常检案检材。1.2方法1.2.1骨骼DNA提取用水洗净骨骼表面,晾干。锯成小块,用锉打磨内外表面。去离子水、乙醇和5%bleach浸泡、晾干,磨成粉末。取骨粉5g;加入0.5mon/L EDTA(pH8.0)溶液,搅拌均匀置于摇床上脱钙12h,去离子水洗两遍,去上清,重复4次[1];沉渣中加入适量裂解液(6mon/L GuSCN,20mo…     

轻型颅脑损伤ABR的纵向研究

目的　探索轻型颅脑损伤的电生理学指标 ,为早期临床诊断和预后判断以及法医学活体伤害鉴定提供依据。　方法　对相关病例进行脑干诱发电位 (ABR)的动态观察 ,并对结果进行统计学分析。　结果　6 0例轻型颅脑损伤患者伤后 48小时ABR的检测 ,显示主要异常表现为I-III峰间潜伏期的延长 ,说明此类损伤可造成脑干的功能紊乱。同时通过对其中 40例进行ABR追踪检测 ,结果显示大部分患者受伤三个月后脑功能状态恢复正常。　结论　轻型颅脑损伤ABR变化具有一定的特征 ,提示可作为早期临床诊断和预后判断以及法医学活体伤害鉴定的客观依据 ,应引起关注并展开进一步研究。     

人离体肝组织胺类产生与死亡时间和环境温度的关系

目的探讨在不同环境温度下,人离体肝组织中有机胺类产生量随死亡时间变化的规律,为某些碎尸案的死亡时间推断提供参考资料。方法应用高效液相色谱仪外标法,动态检测人离体肝组织中组胺、腐胺、尸胺和未腐败氨基酸含量。结果在8℃、15℃、23℃和32℃环境下,有机胺类产生量分别于人死后肝脏即刻离体69h、54h、40h和33h趋于最大值,并且在到达峰值之前,各温度组离体肝组织中有机胺类生成量均与死亡时间成正比关系。结论人离体肝组织中有机胺类产生量与死亡时间和环境温度在一定范围内均呈正相关。     

冠状动脉内弹力膜缺损与冠心病猝死的关系

目的探讨冠状动脉内弹力膜(IEL)病变与冠心病猝死(SCD)的关系。方法从本单位近5年尸检案例中挑选60例病例和心脏标本,分为SCD组、对照组A和B组。每例分别在冠状动脉左前降支近段取材,常规制片,HE和双重组合特殊染色,显微镜下观察冠状动脉IEL,并用图像分析技术对特殊染色的IEL进行形态定量分析。结果60例中,SCD组(男性24例,女性6例,年龄30~83岁)的冠状动脉IEL缺失明显(缺失率=41.64%),未缺失的IEL失去原有弯曲度而变平直;对照组A(冠心病非猝死者,男性13例、女性2例,年龄41~80岁)的冠状动脉IEL缺失程度较SCD组稍轻(缺失率=30.53%);对照组B(无冠心病的其他死者,男性8例,女性7例,年龄17~54岁)的冠状动脉IEL仅有轻度缺失(缺失率=15.67%),多保持原有波浪状结构。统计学分析显示,SCD组与对照组、SCD组与对照组B、对照组A与对照组B之间IEL缺损率的差异均具有极显著性意义;SCD组与对照组A在IEL缺损率上的差异有显著性意义。结论SCD与其冠状动脉IEL缺损率的大小密切相关。