Touch DNA collection from improvised explosive devices: A comprehensive study of swabs and moistening agents

Improvised explosive devices (IEDs) are used in devastating terrorist attacks worldwide and daily in Thailand. Touch DNA deposited during IED assembly are subjected to intense heat and pressure, resulting in rare events of usable DNA profiles obtained from real casework. No study has simultaneously evaluated both swab brands and moistening agents for touch DNA collection from substrates encountered in IED evidence. In this study, we investigated the effects of swab brands and moistening agents on DNA collection from adhesive tape, a common IED substrate. A full factorial design using four cotton swab brands (two forensic and two medical cotton swabs) and six moistening agents (DNA-free water, phosphate-buffered saline, ethanol, sodium dodecyl sulfate, isopropanol, and lysis buffer) was employed (24 total combinations). Using buffy coats, we found that DNA recovery depended on both swab brands and moistening agents (p < 0.05). The optimal method recovered significantly higher DNA amount from real IED cases compared to the standard Royal Thai Police method. Percentages of high partial profiles also increased. Our results changed the standard operating protocol of the Thai police. Other commonly found substrates from IED cases are being investigated to maximize the evidential value obtained from touch DNA.     

Estimating Individual Contributions to Complex DNA SNP Mixtures.,

High‐throughput sequencing (HTS) of large panels of single nucleotide polymorphisms (SNPs) provides an alternative or complimentary approach to short tandem repeats (STRs) panels for the analysis of complex DNA mixture forensic samples. For STRs, methods to estimate individual contribution concentrations compare capillary electrophoresis peak heights, peak areas, or HTS allele read counts within a mixture. This article introduces three approaches (mean, median, and slope methods) for estimating individual DNA contributions to forensic mixtures for HTS/massively parallel sequencing (MPS) SNP panels. For SNPs, the major:minor allele ratios or counts, unique to each contributor, were compared to estimate contributor proportion within the mixture using the mean, median, and slope intercept for these alleles. The estimates for these three methods were typically within 5% of planned experimental contributions for defined mixtures.     

The CSI Effect and the impact of DNA evidence on mock jurors and jury deliberations

ABSTRACT

The present research examined the CSI Effect and the impact of DNA evidence on mock jurors and jury deliberations using a 3 (Crime Drama Viewing: low, moderate, high)?×?3 (Evidence: DNA innocent, DNA guilty, no DNA control) design. A sample of 178 jury-eligible college students read a case of breaking and entering. Pre-deliberation, some support for a CSI Effect was found with high viewers’ extent of guilt ratings significantly lower than moderate and low viewers’ in the no DNA control and the DNA innocent conditions. This effect was not present for verdicts. Contrary to a CSI Effect, crime drama viewing was not related to guilt judgments with incriminating DNA evidence. A content analysis of comments made during deliberations found little support for the CSI Effect entering the jury room. Specifically, CSI Effect predictions were not supported when examining the discussion of DNA evidence, expressing DNA opinions, or mentioning missing evidence. Overall, the limited CSI Effect found for individuals was attenuated during deliberation. The alarm raised over a possible CSI Effect influencing jury decision making may be unwarranted.     

Validation studies of the ParaDNA® Intelligence System with artificial evidence items

Short tandem repeat (STR) profiling is one of the mostly used systems for forensic applications. In certain circumstances, STR profiling is time-consuming and costly, which potentially leads to delays in criminal investigations. LGC (Laboratory of the Government Chemist, UK) Forensics has developed a robust STR profiling platform called the ParaDNA^® Intelligence Test System which can provide early tactical intelligence and aid investigators in making informed decisions on sample prioritization for detection. Here, we validated the ParaDNA intelligence test for its application in forensic cases using a range of mock evidence items following guidelines set by the Scientific Working Group on DNA Analysis Methods (SWGDAM). Specifically, we tested the sensitivity and accuracy of the ParaDNA intelligence test, as well as the success rates for detecting mock samples and for use in case scenarios. Our findings demonstrate that the ParaDNA intelligence test generates useful DNA profiles, especially for samples such as blood, saliva, and semen that contain ample DNA, indicating the benefits of including ParaDNA as a prior step in forensic STR profiling pipelines.     

口蹄疫病毒O型和A型交互反应性单克隆抗体的筛选与鉴定

不同血清型口蹄疫病毒(FMDV)之间不能产生交叉免疫保护,但是血清学的交叉反应确实存在。本研究旨在建立一种筛选型间交互反应性抗体的方法,以期为解析FMDV血清型间保守的抗原结构奠定基础。本方法主要依据单个B细胞抗体技术,首先采用两种不同的荧光染料FluoProbes 647H和Pacific Blue分别标记O型与A型FMDV 146S灭活抗原,然后利用流式细胞分选技术,从免疫牛外周血单个核细胞(PBMCs)中分选出结合两种抗原的特异性B细胞,通过单个B细胞抗体基因测定,获得Ig G抗体重链与轻链可变区编码序列,并将可变区基因插入含有牛IgG抗体恒定区的pcDNA3.4载体中,构建IgG抗体的重链与轻链表达质粒。将重链与轻链表达质粒共转染中国仓鼠卵巢悬浮细胞(CHO-S)进行完整抗体表达。结果显示,通过该方法获得了5株FMDV特异性单克隆抗体,其中4株(H64、R82、I16、R29)经间接免疫荧光(IFA)检测都可特异性识别O和A型FMDV;ELISA结果显示,H64、R82、I16与O、A型抗原均具有较好的亲合力;Western-blot结果显示,I16可特异性结合O、A型FMDV结构蛋白VP2中的线性表位,说明在衣壳蛋白VP2上存在血清型间保守的抗原表位,通过本研究进一步加深了对FMDV抗原结构的认识。     

浅论犯罪心理画像在我国刑侦实践中的应用

犯罪心理画像主要是运用精神分析、行为心理学的理论和原理对与犯罪有关的行为进行分析,以提供犯罪行为人最为可能的人格特征、心理特征、行为特征等信息,从而协助侦查机关确定侦查范围的一种技术和方法。近些年来,犯罪心理画像已越来越多的引起侦查学界的关注和兴趣。然而只有正确理解和把握犯罪心理画像的适用条件、研究方法、以及厘清刑事科学技术与其的关系,才能更好的将其应用于侦查实践之中。犯罪心理画像可适用于任何刑事案件,关键在于通过剖析、研究个案中犯罪行为人的心理,积累行为资料,为侦查实践提供理论支持和案例指导。     

论现场勘验人员的安全防护

现场勘验人员的安全防护理应是现场勘查技术中现场保护的主要研究内容。长期以来,对现场保护的研究只是片面强调了对现场的保护,对现场上痕迹、物品及尸体的保护,而对现场勘验人员的安全防护却仅依靠其自身的生活与工作经验,或只是师徒传承等基础之上的自发、盲目的行为。目前,在现场勘验过程中的人员伤亡事故频频发生,教训屡见不鲜,使得现场勘验人员的安全防护成为现场保护薄弱、滞后的研究领域。现场勘验工作本身就是一个需要全体参与人员相互协作配合的团队工作,现场勘验人员的安全防护自然也概莫能外。     

警察在干预自杀事件中的作用

自杀是一个严重的社会问题。面对当前日益严峻的自杀问题,警察作为维护国家安全、维护社会治安秩序、保护人民生命财产安全的重要力量,在多数情况下是自杀现场的第一处置人员。因此,正确认识自身在处理自杀事件中的角色,掌握恰当的干预自杀的方法与技巧,对于警察来说是极其重要的。     

秘密侦查性质的多维解读

传统上我国学术界普遍从手段或措施的角度对秘密侦查予以认识。这种认识缺陷导致人们对秘密侦查“神秘化”,秘密侦查法治化状况极差。从诉讼法理上而言,秘密侦查的性质应为一种侦查行为和诉讼行为,它具有自身的特征,与强制侦查行为和技术侦查行为有一定的区别。     

DNA指纹图在法医学鉴定中应用的研究(Ⅰ)

应用 MYO DNA 探针对中国人进行了 DNA 遗传指纹图检验。从两个家系16人及100个无关个体中取肘静脉血提取 DNA,用限制性内切酶 HinfⅠ或 HaeⅢ水解,1%琼脂糖凝胶电泳分离,经 Southern印迹转移,MYO DNA 探针杂交,获得了清晰可辨的 DNA 指纹图谱。结果每个个体在3.0Kb 以上均能检出10条以上杂交区带,个体间的相关概率<4×10~(-9),由杂交区带构成的图谱是个体特异的,杂交区带遵循孟德尔的显性遗传方式由亲代向子代遗传;具有 DNA Fingerprints 的特点。对两起亲子鉴定的案例进行指纹图检验,孩子所存在的杂交区带,除来自母亲外,其余可在嫌疑父亲带中找到,肯定了孩子与嫌疑人的父子关系。MYO DNA 探针在亲子鉴定与个人识别的法医学鉴定中有着重要的实用价值。