A new method for the recovery and evidential comparison of footwear impressions using 3D structured light scanning

Footwear impressions are one of the most common forms of evidence to be found at a crime scene, and can potentially offer the investigator a wealth of intelligence. Our aim is to highlight a new and improved technique for the recovery of footwear impressions, using three-dimensional structured light scanning. Results from this preliminary study demonstrate that this new approach is non-destructive, safe to use and is fast, reliable and accurate. Further, since this is a digital method, there is also the option of digital comparison between items of footwear and footwear impressions, and an increased ability to share recovered footwear impressions between forensic staff thus speeding up the investigation.     

Novices cannot fill the examiners’ shoes: Evidence of footwear examiners’ expertise in shoe comparisons

The value of a footwear examiner’s opinion centres on their ability to determine whether a particular shoe made an impression with greater accuracy than a novice. However, there has been limited research on the expertise of footwear examiners and the accuracy and reproducibility of their decisions. In the current study, we measured the accuracy and consensus of 31 footwear examiners versus a comparison group of 29 novices. Participants completed 20 ground truth known mock shoe comparisons. Results demonstrated that footwear examiners were more accurate than novices, regardless of comparison difficulty. Overall, on trials where probative decisions were given, examiners made false identifications and false exclusions on a total of 3% and 2% of trials, while novices made false identifications and false exclusions on a total of 19% and 17% of trials. Examiners also demonstrated better consensus in their opinions than novices, although both groups demonstrated low levels of agreement in their responses and variability in their interpretation of the conclusion scale. In summary, these findings support the proposition that footwear examiners show expert-level performance in matching known and unknown footwear impressions. These performance estimates may help the criminal justice system to appropriately value footwear examination evidence.     

改良IPEP法用于痕量DNA检测的实验研究

目的探讨改良扩增前引物延伸(IPEP)法对痕量DNA样本STR检测分型的效果。方法用改良IPEP法对痕量样品DNA进行全基因组扩增(WGA),扩增产物用实时荧光定量PCR技术定量、用AmpFLSTR~ Indentifiler~试剂盒作基因型检测。结果该方法可增加模板DNA约200~1100倍。基因组DNA不低于0.025ng时,可获得15个STR基因座和Amelogenin性别基因座的分型结果。基因组DNA0.01~0.025ng时,可获得9个以上基因座的分型结果。结论改良IPEP法可有效提高痕量DNA样本STR分型检验的灵敏度,有较好的实用价值。     

人类DRB基因单核苷酸多态性研究

目的建立一种对单核苷酸多态性(SNPs)位点进行复合检测的方法,并对人类DRB基因的单核苷酸多态性进行研究。方法 应用荧光标记双脱氧核苷酸进行单碱基延伸反应,同步检测人类DRB基因10个单核苷酸多态性位点。结果 应用该方法检验了人类标准细胞株K562、9947A及其他法医学常见生物检材,包括血斑2份、精斑5份、烟蒂8份、毛发3份,各样品间未发现相同的单核苷酸多态性组合单倍型。DNA模板需要量仅为0.5~1.0ng。结论 该方法是对微量生物物证进行个体识别鉴定的理想方法。同时还可为法医学及其他研究领域进行单核苷酸多态性分析提供快速、高效的技术手段。     

论法医专家顾问和法医鉴定结论的质证

根据证据学的观点提出法医鉴定结论是一种科学证据,指出无论是民事诉讼还是刑事诉讼中,对其进行质证对维护司法公正的必要性和重要性。由于法医鉴定结论的专业性,对其质证时,当事或控辩双方,以及法院聘请法医专家顾问,协助对法医鉴定结论的质证具有重要的意义。     

The importance of forensic evidence for decisions on criminal guilt

Recent studies have found that the general public perceives forensic evidence to be relatively inaccurate and to involve high levels of human judgement. This study examines how important the general public finds forensic evidence by comparing decisions on guilt and punishment in criminal cases that involve forensic versus eyewitness testimony evidence and examining whether a CSI effect exists. Specifically, this experimental survey study utilized a 2 (crime type: murder or rape) × 4 (evidence type: DNA, fingerprint, victim eyewitness testimony, or bystander eyewitness testimony) ? 1 (no victim testimony for murder scenario) design, yielding seven vignettes scenarios to which participants were randomly assigned. Results indicate that forensic evidence was associated with more guilty verdicts and higher confidence in a guilty verdict. Forensic evidence did not change the expected sentence length and did not generally affect the ideal sentence length. However, for rape, respondents believed that the defendant should receive a longer sentence when forensic evidence was presented but forensic evidence did not alter likely sentence that respondents expected the defendant to receive. The results of this study did not support a CSI effect. Overall, this study suggests that forensic evidence – particularly DNA – has a stronger influence during the verdict stage than the sentencing stage.     

The reincorporation and redistribution of trace geoforensic particulates on clothing: An introductory study

Two experimental studies were undertaken to investigate the processes of reincorporation and redistribution of trace evidence on garments when worn by a suspect or a victim (reincorporation) or after the garments have been seized and packaged for subsequent forensic analysis (redistribution). The first experiment utilised UV powder, an established proxy for geoforensic trace particulates and the second experiment utilised daffodil pollen transferred onto garments under conditions that mimicked forensic reality. It was demonstrated that reincorporation of trace particulates occurs from upper to lower parts of the same garment and also from upper garments to lower garments. Reincorporation also occurred to all areas of the lower garments, however the highest concentration of particulates was found to be the lap area of the jeans. Particulates also tended to be preserved around technical details such as stitching or relief design features of the garments. Thus the decay of particulates after a contact has been made does not necessarily involve a loss of those particulates from the entire system. These findings have implications for the interpretation of trace evidence when seeking to establish the source of initial contacts or the chronology of pertinent events. The second study demonstrated that folding and packaging items of clothing leads to a redistribution of any trace particulate evidence that is present thereby eliciting an alteration in the spatial distribution of that evidence. There is therefore a necessity to take the context of trace evidence into account and also to follow protocols that are sensitive to these aspects of trace evidence behaviour as a failure to do so may have consequences for the correct interpretation of such evidence.     

论法医学鉴定意见与案情的关系

本文从三个方面进行论述,即法医学鉴定意见的案情趋向性;法医学鉴定中的案情资料价值;法医学鉴定的科学局限性。从而说明法医学鉴定在很多情况下依赖案情,对法医学鉴定意见进行审查判断十分必要。     

刑事诉讼视野下的法医物证应用研究

法医物证在刑事诉讼中发挥着多种功能,但目前实践中对法医物证的有效发现、提取、保管、检验鉴定及应用的技术规范和证据规则尚不完善。本文从技术规范、诉讼程序以及证据应用的角度发掘法医物证应用的规律性内容,用以指导实践部门提高法医物证的发现、提取、检出的比率以及法医物证在刑事审判中的采用率及证明力,从而较好地解决定案证据的来源和案件事实的认定问题,并避免因法医物证错用而导致的错案。     

组织切片DNA提取的探讨

在医患关系纠纷中,病理组织切片经常被作为至关重要的证据,但对它的检验是目前法医DNA检验的难点。因样本制作固定的时间、保存环境等不同因素的影响,病理组织切片DNA检出率并不高。本文从实际检案角度出发,详细介绍了病理组织切片DNA提取的过程,并分析了其可能影响因素。     

法证科学领域的决策

随着法证DNA证据以及它所适用的概率模型日益凸显,反映了传统法证科学的局限性,并使人们对法证科学领域的决策产生了越来越多的质疑,焦点集中在对结论的解读方式和实际运用。分析表明,科学证据的本质不是绝对性或确定性的,而是概率性的;同时,事实审判者需要基于这些概率性的证据对事实作出明确的决定。因此,对于法证科学领域的决策,应当是专家在一系列归纳得出的特定假设基础上,就研究结果的概率进行恰当的报告,由事实审判者承担对概率作出决断的任务。