Forensic laboratory backlog: The impact of inconclusive results of marijuana analysis and the implication on analytical routine

Forensic laboratories worldwide are struggling to keep up with the increasing number of cases submitted for analysis, regardless of the reasons, backlog of controlled substances cases is a reality in many countries. In this paper we analyse the number of petitioned examinations (from 2016 to 2020) and the data from 11,655 marijuana TLC results from the Forensic Laboratory in the Federal District Civil Police in Brazil. Data demonstrates that backlog increases inconclusive results, with storage and light playing a crucial role in the process. Additionally we explored the repercussions of delayed forensic results for controlled substances and propose an approach to overcome waiting time in this context.     

The distinction between discriminability and reliability in forensic science

Forensic science plays an increasingly important role in the criminal justice system; yet, many forensic procedures have not been subject to the empirical scrutiny that is expected in other scientific disciplines. Over the past two decades, the scientific community has done well to bridge the gap, but have likely only scratched the tip of the iceberg. We offer the discriminability-reliability distinction as a critical framework to guide future research on diagnostic-testing procedures in the forensic science domain. We argue that the primary concern of the scientist ought to be maximizing discriminability and that the primary concern of the criminal justice system ought to be assessing the reliability of evidence. We argue that Receiver Operating Characteristic (ROC) analysis is uniquely equipped for determining which of two procedures or conditions has better discriminability and we also demonstrate how estimates of reliability can be extracted from this Signal Detection framework.     

The forensic investigation of vehicle–pedestrian collisions: A review

Rapid urbanisation, a steady increase in the number of vehicles, speeding, negligence in road safety, and other factors have led to the inevitable worldwide growth of road traffic accidents involving pedestrians. According to the ‘Global Status Report on Road Safety’ released by the World Health Organization, road traffic collisions are one of the leading causes of death for people of all ages, with approximately 1.35 million road fatality deaths occurring globally each year. Figures from the report also highlight that a large part of road deaths involves pedestrians as the most vulnerable road users. Therefore, forensic examination of vehicle–pedestrian collisions has become increasingly important in the detection, investigation and reduction of road casualties and permanent development of this discipline is urgently needed. Thus, this article aims to review the capability and effectiveness of forensic examination in tackling road fatalities and explores the most important aspects of this discipline, such as nature of a vehicle–pedestrian collision, common issues resolved by this type of examination and typical physical evidence used in the reconstruction of vehicle–pedestrian collisions. Moreover, the paper outlines the latest advances and approaches in the field.     

DNA-based and taxonomic identification of forensically important Sarcophagidae (Diptera) in southeastern Spain

Studying dipterans at the scene of a death can provide essential information for interpreting the evidence and help to reconstruct the events happened to a corpse in the past. Molecular tools have been employed for identification at specific levels in the cases of cryptic species or poorly conserved specimens. Identification of specimens is essential in forensic entomology since each species has a specific growth rate, which determines the calculation of the minimum post mortem interval (minPMI). In addition, phylogeographic reconstruction within a species can help to differentiate the haplotypes from a geographic area, thereby helping to clarify the possible relocation of a corpse. The morphological identification of Sarcophagidae species is often difficult, especially for the females. This is an important Diptera family since some of its species are among the first to reach a corpse, especially in warm areas. In this study, we compared the sarcophagids found in human corpses in forensic cases in Alicante (southeast of Spain) with specimens collected from baited traps in the same area and surrounding provinces. In total, 189 specimens were collected, comprising 72 from forensic cases and 117 from baited traps. Molecular identification was conducted by sequencing the cox1 mitochondrial gene and analyzing the sequences using ABGD, GMYC, and BIN species delimitation methods. The median joining algorithm in the PopART program was used to construct phylogeographic networks. Eight species in the family Sarcophagidae were identified. The most widely collected species were Sarcophaga argyrostoma and Sarcophaga tibialis. The haplotype networks obtained for these species did not indicate a clear geographic distribution of haplotypes. The S. argyrostoma samples from Alcoy were clearly isolated. The results demonstrated that this method is useful for identifying Sarcophagidae samples in forensic investigations and it can be employed for minPMI estimation.     

Blood and sperm traces on human hair. A study on preservation and detection after 3-month outdoor exposure

Hair can retain important biological traces for forensic investigations. Forensic scientists are used to looking for such traces on clothing and skin of victims, however, when decomposition kicks in and all that remains of the victims is the skeleton, hair may be the only tissue representing the surface of the body at the time of a crime on which biological traces of an aggressor may have been left and still be detectable. Given the lack of research on this topic, this pilot study aims to assess the capacity of hair to retain semen and blood in hair, and the possibility to detect these fluids with well-known techniques and to obtain a useful genetic profile even when exposed to environmental conditions (Open Natural Environment (woods), Open Man Made Environment (urban)) for three months.Results showed that both traces were always visible and detectable with almost all techniques in the Control Environment, while in the two open environments some difficulties arose. However, biomolecular analysis was effective up to three months on both fluids in the Natural Environment and up to two months and one week respectively on blood and semen in the Man Made Environment. The Combur Test, OBTI, and Luminol were effective on blood up to three months in both environments while Sperm-HY-Liter and observation of cellular components were effective on semen up to at least 1 month and PSA testing was positive up to 1 week in both environments.The present work can be considered an encouraging starting point for the analysis of biological traces on hair in forensic contexts, regardless of the PMI, since blood and semen related to a crime may survive.     

Shifting forensic science focus from means to purpose: A path forward for the discipline?

Forensic science is facing a persistent crisis that is often addressed by organizational responses, with a strong focus on the improvement and standardisation of means and processes. However, organisations and processes are highly dependent on the political, economical and legal structures in which they operate. This may explain why most proposed solutions had difficulties in addressing the crisis up to now, as they could hardly be applied transversally to all forensic science models. Moreover, new tools and technologies are continuously developed by a quasi-infinite number of different scientific disciplines, thus leading to further diversity and fragmentation of forensic science. In this paper, it is proposed to shift the focus from means to purpose and consider forensic science current challenges in terms of discipline, before addressing organisations’ specific issues. As a distinct discipline, forensic science can refocus research and development on shared principles and purposes, such as reconstructing, monitoring, and preventing crime and security issues. This focus change will facilitate a better understanding of the trace as the object of study of forensic science and eventually lead to a more impactful and long-lasting effect. This approach will also foster the development of a forensic science culture (instead of a primarily technological culture) unified by purpose rather than means through more relevant education and research.     

Stature estimation using foot dimensions via 3D scanning in Taiwanese male adults

In forensic identification, the use of foot dimensions to predict stature is a requisite. For Taiwanese male stature prediction, available information about stature estimation using foot dimensions is still lacking. Therefore, the primary purpose of this study was to establish Taiwanese adult male stature prediction models for various foot dimensions. A total of 2,072 male 3D foot models were collected and the subjects' ages ranged from 18 to 59 years old. Thirteen foot dimensions for each foot were utilized in this study. Bilateral differences were tested using paired t-tests. Stature predictions based on different foot dimensions were conducted using simple linear and stepwise regression methods. The results showed significant bilateral differences in the majority of the selected foot dimensions (p < 0.001). Foot length had the highest positive correlation with stature in the right and left foot. Using length-related dimensions generated better prediction accuracy (0.356 < R² < 0.533, 4.193 < SEE < 4.928), whereas the worst accuracy was observed with angle-related dimensions (0.001 < R² < 0.023; 6.072 < SEE < 6.137) when employing a single foot dimension to estimate Taiwanese male stature. Stepwise regression analysis results indicated that the coefficient of determination was improved to 0.590 and 0.593 by applying five and six foot parameters to predict stature, respectively. The findings of the present study suggest that these stature estimation equations can be applied to predict Taiwanese male stature in the forensic science field.     

基于miRNA相对表达量自动判别月经血和外周血

目的探索有效区分月经血和外周血的miRNA最优标记组合及最佳分类模型,并构建简便快速的自动化判别软件。方法对10种miRNA(miR-451a、miR-205-5p、miR-203a-3p、miR-214-3p、miR-144-3p、miR144-5p、miR-654-5p、miR-888-5p、miR-891a-5p、miR-124-3p)在200余份月经血和外周血样本中的相对表达量以实时荧光定量PCR检测,并以7种算法模型(核密度估计、K-最近邻、逻辑回归、线性判别分析、支持向量机、神经网络、随机森林)进行数据分析,选出鉴别效果最好的标记组合及算法模型,进而构建自动判别软件。结果月经血和外周血中差别最大的三种miRNA为miR-205-5p、miR-203a-3p和miR-214-3p,使用miR144-5p与上述miRNA中的一种或两种组合可达较好区分效果,其中基于miR-144-5p、miR-203a-3p和miR205-5p所形成的“最优特征项组合一”稳健性最强。7种算法模型中最佳分类模型为核密度估计模型,其次为逻辑回归模型。结论本研究建立的自动判别软件界面友好、使用简单,适合辅助法医检验关于月经血和/或外周血判别分析的计算,便利于法医物证工作,有较大的推广应用价值。     

基于年龄相关DNA甲基化位点推断河南汉族个体年龄

目的探查中国河南汉族个体与年龄相关的DNA甲基化位点,构建年龄推断模型,进行甲基化和年龄相关性分析。方法采用焦磷酸测序法对ELOVL2、ClOrf132、KLF14、TRIM59和FHL2基因的34个CG位点进行甲基化分析,利用SPSS 23软件的多元回归方法建立模型,对甲基化和年龄相关性做分析。结果除ClOrf132基因3个CG位点的甲基化水平与年龄呈负相关外,其余4个基因的31个CG位点甲基化水平均与年龄呈正相关。多元回归分析表明,年龄与CG位点的甲基化水平存在明显的线性关系,实际年龄与推断年龄偏差在5岁以内的准确度达80%以上。结论本研究构建的河南汉族个体年龄推断模型,有助于通过检测血液等组织的DNA甲基化水平推断个体的年龄范围,具有法医学应用前景。     

我国刑罚体系的反思与重构

在刑罚轻缓化的浪潮中,对我国刑罚体系的反思是刑罚改革的必然要求。刑罚体系的反思,必须正确认识刑罚的本质,树立正确的刑罚理念。目前,我国刑罚体系存在着死刑过重、生刑过轻、非监禁刑适用较少、刑罚结构不合理、各刑种衔接不完善等诸多问题。因此,对现行刑罚体系的重构应当从限制死刑、提高生刑、扩大罚金刑的适用和完善资格刑等方面入手。理念的更新和制度的完善,将促进我国刑罚轻缓化进程,进而推动我国法治的进步。