Evaluation of canine training aids containment for homemade explosive and components by headspace analysis and canine testing

While canines are most commonly trained to detect traditional explosives, such as nitroaromatics and smokeless powders, homemade explosives (HMEs), such as fuel–oxidizer mixtures, are arguably a greater threat. As such, it is imperative that canines are sufficiently trained in the detection of such HMEs. The training aid delivery device (TADD) is a primary containment device that has been used to house HMEs and HME components for canine detection training purposes. This research assesses the odor release from HME components, ammonium nitrate (AN), urea nitrate (UN), and potassium chlorate (PC), housed in TADDs. Canine odor recognition tests (ORTs) were used with analytical data to determine the detectability of TADDs containing AN, UN, or PC. Headspace analysis by gas chromatography/mass spectrometry (GC/MS) with solid-phase microextraction (SPME) or online cryotrapping were used to measure ammonia or chlorine, as well as other unwanted odorants, emanating from bulk AN, UN, and PC in TADDs over 28 weeks. The analytical data showed variation in the amount of ammonia and chlorine over time, with ammonia from AN and UN decreasing slowly over time and the abundance of chlorine from PC TADDs dependent on the frequency of exposure to ambient air. Even with these variations in odor abundance, canines previously trained to detect bulk explosive HME components were able to detect all three targets in glass and plastic TADDs for at least 18 months after loading. Detection proficiency ranged from 64% to 100% and was not found to be dependent on either age of material.     

ID‐Check: Online Concealed Information Test Reveals True Identity

The Internet has already changed people's lives considerably and is likely to drastically change forensic research. We developed a web‐based test to reveal concealed autobiographical information. Initial studies identified a number of conditions that affect diagnostic efficiency. By combining these moderators, this study investigated the full potential of the online ID‐check. Participants (n = 101) tried to hide their identity and claimed a false identity in a reaction time‐based Concealed Information Test. Half of the participants were presented with personal details (e.g., first name, last name, birthday), whereas the others only saw irrelevant details. Results showed that participants′ true identity could be detected with high accuracy (AUC = 0.98; overall accuracy: 86–94%). Online memory detection can reliably and validly detect whether someone is hiding their true identity. This suggests that online memory detection might become a valuable tool for forensic applications.     

Improving Luminol Blood Detection in Forensics

The aim of this study was to develop chemical improvements to the original Weber protocol, in order to increase the intensity and time length of light emission and to eliminate false‐positive reactions. The intensity and duration of light were measured on serial blood dilutions using a plate reader chemiluminometer. Blood stains of various concentrations were impregnated in pure cellulose, dried, and luminol solution was added with/without the potential enhancers. An in silico study was also conducted, aiming to demonstrate the enhancing mechanism of hemoglobin denaturation using 8 M urea. The luminol blood detection test revealed important improvements after urea pretreatment or in the presence of monochloro‐triazinyl‐β‐cyclodextrin. This approach also eliminated the false‐positive reaction from sodium hypochlorite. These improvements could provide a higher sensitivity under particular circumstances such as old or washed blood stains, leading to a better localization for further DNA typing and higher quality photographic analysis.     

人隐瞒信息状态下多通道事件相关电位的研究

目的采用隐瞒信息测试(concealed informationtest,CIT)模式和多通道事件相关电位(event related potential,ERP)技术,对人类大脑在不同刺激下各脑区域活动情况和活跃程度进行对比,从神经电生理学层面揭示CIT模式隐瞒信息状态下视觉刺激人类大脑认知相关脑功能区特征。方法参考犯罪知情测试模式(GKT)的CIT模式,选用传统扑克牌,对17名被试人员进行视觉刺激,包括:靶、探测、无关和中立刺激,获得29通道ERP波。结果靶、探测和无关刺激平均按键反应时间:775ms、774ms和720ms;探测和无关刺激各通道P300峰潜伏期配对t检验,有统计学意义(P0.05)的通道有4个;探测和无关刺激各通道P300平均波幅(400~700ms)进行配对t检验,有统计学意义(P0.05)的通道有19个。结论隐瞒知晓信息是一个由多个脑功能皮质共同完成的复杂过程,与诚实反应抑制有密切关系,与额叶前部和上部皮质、前扣带回皮质(ACC)和缘上回等脑功能皮质特异相关。     

六色荧光标记快速PCR扩增体系的建立及验证

目的建立PCR快速扩增程序和体系,并对其技术指标进行验证。方法采用六色荧光标记技术,对24个常染色体STR基因座、1个Y-STR基因座和Amelogenin、Y-In Del基因座进行复合扩增及毛细管电泳检测,同时考察体系的灵敏度、特异性、同一性、稳定性、混合样本及批量样本测试,并观察各种常见检材及降解、脱落细胞检材的分型情况。结果所建立的体系灵敏度达0.062 5 ng,快速扩增仅耗时65 min就可获得准确分型;种属特异性高;各种纸质血样本和混合、降解、脱落细胞检材的分型正确。结论本研究建立的快速扩增体系可显著提升检验速率,分型准确、稳定,对建立STR数据库、研究群体遗传学和进行法医学鉴定有重要意义。     

爆炸案件现场重建初探

随着国际恐怖主义活动的日益猖獗,爆炸案件也呈逐年上升之势,爆炸案件向来是公安机关重点打击的刑事犯罪之一,因此爆炸案件的侦破工作显得尤为重要。而现场重建运用于现场破坏严重、现场范围大且难度天的爆炸案件现场勘查中有其独特的优势。分析爆炸案件特点、爆炸现场重建要解决的问题,探讨采集现场重建各要素的方式,整合刑事技术方面的多重信息,针对爆炸现场最大限度地提出重建与恢复的步骤、方法,从而使现场重建在爆炸案件侦破工作中发挥其重要作用。     

侦查权的性质及配置模式研究

关于侦查权的性质定位,在我国学界存在行政权说、司法权说、行政权和司法权双重性质说。侦查权作为警察权的一部分,应该是一种行政权。侦查权作为一种重要的国家行政权,在行使过程中存在着两种不同的利益需要,即确保侦查效率与保障人权。科学、合理的侦查权配置,能够确保国家权力得以实现、公民权利得以保障。     

谈目标轨迹在侦查思维中的应用

目标轨迹,是指与刑事案件相关的物证和信息,依据发生的时间顺序,建立方向性的连接,构成点与射线组成的图形。目标轨迹能够将事物的过去、现在和将来联系起来,是侦查思维的外化和表现,它通过对犯罪嫌疑人实施犯罪阶段前后的活动情况进行分析、研究,有助干侦查人员把握侦查的主动权,提高侦查工作效能。文章从侦查思维的角度出发,阐释了目标轨迹在侦查工作中的价值、作用和意义。     

沙门菌PCR快速检测试剂盒的研制与应用

为建立一种简单、快速、灵敏、准确的沙门菌检测方法,根据沙门菌fimY保守基因序列设计合成了1对引物,建立了快速检测沙门菌的PCR方法,并对反应条件进行优化,组装成快速检测试剂盒。结果显示,所有沙门菌均扩增出526 bp的特异性条带,而非沙门菌均未扩增出任何条带。检测灵敏度达93 CFU,还可检出含3 CFU的样品用BP预增菌的菌液或用MM增菌后的菌液,而且稳定性良好,冷冻至少能保存12个月。采用直接菌体加入法、热裂解法、反复冻融法、CTAB碱裂解法和柱式试剂盒提取法分别提取核酸模板,结果CTAB法效果最好,但操作烦琐,而直接菌体加入法和热裂解法可以达到和柱式试剂盒提取法相同的效果,且操作简便、快速、经济、效果好。通过对临床样品的检测,证实该试剂盒具有操作简便、快速、灵敏度高、特异性强、重复性好、稳定性高等优点,值得推广应用。     

结核分枝杆菌与牛分枝杆菌PCR快速鉴别检测方法的建立

根据结核分枝杆菌与牛分枝杆菌基因组的比对分析结果,针对结核分枝杆菌与牛分枝杆菌153bp、RD10和TbD1的3处差异缺失区域设计引物,分别建立了结核分枝杆菌与牛分枝杆菌PCR快速鉴别检测方法.应用建立的3种方法分别对84株结核分枝杆菌、3株牛分枝杆菌、51株非结核分枝杆菌及9种其他常见菌株进行了检测.结果显示,用针对153 bp缺失片段建立的PCR方法分别在结核分枝杆菌及牛分枝杆菌中扩增出645 bp及492 bp的目的条带;用针对RD10、TbD1建立的PCR方法分别在结核分枝杆菌及牛分枝杆菌中扩增出478 bp及361 bp的目的条带、358 bp及524 bp的目的条带.这3种PCR检测方法的准确率和特异性均为100%.敏感性试验结果显示,这些检测方法对结核分枝杆菌和牛分枝杆菌基因组DNA的检测极限均为10 pg.表明,此方法可用于牛源或人源结核分枝杆菌及牛分枝杆菌的快速鉴别检测.