原子吸收分光光度法鉴别窗玻璃的研究

玻璃碎片是刑事案件现场常见的一种物证。在司法鉴定实践中,通过玻璃碎片的鉴别和同一认定,确定其来源,对侦破案情有较大的价值。目前国内公、检、法部门鉴别玻璃碎片,主要放在受力情况、折射率等物理机械性能的测试,玻璃碎片化学成分的鉴定未见报导。玻璃的主要成分是硅酸盐。不同型号的玻璃,使用性能有不同要求,其成分有较大     

X线荧光分析法鉴别器皿玻璃的研究

玻璃碎片是刑事案件现场经常收集到的重要物证.玻璃制品的种类很多,常见的有窗,生活用品(瓶、杯、盆和镜子等)和实验仪器(烧瓶、烧杯等加热用仪器,量杯、容量瓶、滴定管等量具,试剂瓶和光学仪器).由于不同的玻璃制品应用在不同的场     

第二讲 玻璃检验

<正> 在许多无证人或证人不可靠的案件中,破碎玻璃可能是一主要线索。盗窃犯经常打碎玻璃取得被盗物,盗车犯经常打碎车窗玻璃进入汽车。由于此类犯罪经常无人目睹,所以,侦查人员往往需要以物证,包括玻璃物证中寻找线索。无论何时,当玻璃披人击碎时,虽然看上去所有碎片都是按打击方向向前飞散,但实际上总有些细小颗粒向后飞溅。这些微粒可以在罪犯毫无察觉的情况下嵌入其衣服的皱折处或     

微量物证检验在美国

近年来，随着犯罪活动的日益智能化及反侦查意识的增强，现场常见的痕迹物证明显减少，而像玻璃、纤维、泥土、涂料、油脂及动植物残渣等微量物证往往以其“量小体微”混杂于其它物体中，或附着于其它物体上，不易引起犯罪分子的注意而毁迹。日新月异的鉴定手段和现代分析仪器，可以揭示这些“微不足道”的物证的种类、属性，并从物质组成、形态结构     

X射线荧光光谱法检测玻璃中的常量和微量元素

应用X射线荧光光谱法对常见玻璃物证进行了实验研究,在样品量为mg级时,不但检出Si、Ca等主体元素,还能检出As、Zr、Sr等微量元素.用该方法既可对玻璃的种类进行鉴别,还可对某些种类的玻璃做进一步的区分.     

热分析在微量物证检验中的应用（综述）

微量物证是与犯罪有关联、能认定犯罪事实的、量小体微、甚至用肉眼难以看见的细微物质。微量物证能将嫌疑犯、被害人与犯罪现场有关的情况联系起来,为侦察提供方向和线索。微量物证来源广泛,种类繁多、常见的有纤维、泥土、金属碎屑、毛发、粘合剂、纸张、油脂、油漆、玻璃、塑料、橡胶及爆炸残留物等。微量物证的检验方法有物理性质的测试、化学     

国外微量物证检验研究进展

本文根据近年来国外法庭微量物证检验方面的研究成果,从检验对象、检验技术及发展趋势三个方面总结了当前国外微量物证的研究现状。介绍了近年来国外法庭科学家在常见的微量物证如油漆、纤维、玻璃等的检测方法和检测技术,尤其重点介绍了一些新技术如电感耦合等离子体原子发射光谱技术（ICP/AES）、微波辅助消融和等离子光谱技术（OES...     

交通肇事案件现场木材纤维检验1例

在交通肇事案件的物证检验中，与车辆相关的油漆、塑料、玻璃、橡胶等物证最为常见，而车辆装载的物品有时也会在交通事故中发生转移，并具有十分重要的物证价值。本文介绍一起装载木材的拖拉机撞人后，从被撞人衣服上成功检出微量木材纤维的案例。     

基于折射率数据的玻璃物证比对检验似然比模型建立及评估

玻璃是常见微量物证，目前国内微量物证检验报告通常只列出检验数据或定性给出比对检验结论，无法量化表达物证比对鉴定结论。似然比证据价值评价方法在全世界被广泛接受，但在中国，针对玻璃物证的定量价值评价方法还未建立，给检察官和法官准确利用玻璃物证带来困难。为提升玻璃物证的证据价值，本文拟建立量化比对检验结论的似然比方法模型并进行评估。基于四大类150个玻璃样品共750个折射率的检验数据，采用高斯核密度估计方法建立似然比(LR)模型，采用直方图和两类错误率对该模型进行评估。通过建立的似然比模型计算得出同源样品间的LR值在6.58～204 500范围内，不同源的样品间的LR值在0～0.68范围内，在150个样品的自身比对中，仅有一个样品自身比对的LR<1，错误排除率为0.67%；对150个不同来源玻璃样品进行两两比对，在C²₁₅₀=11 175对比对中，有173对LR>1，错误接纳率为1.55%，两个错误率均较低，在可接受范围内。基于高斯核密度估计建立的似然比模型能够对基于玻璃折射率数据的样品比对给出满意的比对结果，可为法庭提供玻璃样品比对的...     

国外微量物证检验研究进展

本文根据近年来国外法庭微量物证检验方面的研究成果,从检验对象、检验技术及发展趋势三个方面总结了当前国外微量物证的研究现状。介绍了近年来国外法庭科学家在常见的微量物证如油漆、纤维、玻璃等的检测方法和检测技术,尤其重点介绍了一些新技术如电感耦合等离子体原子发射光谱技术(ICP/AES)、微波辅助消融和等离子光谱技术(OES/ICP)、激光等离子质谱联用技术(LA/ICP/MS)等在微量物证中的应用。指出国外微量物证研究相对于国内微量物证研究在技术应用、数据库建立、数据分析、合作研究等方面的优越性。     

撞击角度和速度已知条件下的球形弹丸飞行弹道轨迹算法

针对刑侦工作中弹打玻璃类案件的侦破难点,研究一种用于计算球形弹丸抛射击打玻璃案件中弹丸飞行轨迹的算法。本文以弹丸撞击角度和撞击速度为基础参数,在阐明前置基础数据的前提下,将弹打玻璃类案件中的玻璃窗分为垂直于地面及倾斜于地面两类,采用三角函数计算和参数替换的方法,通过对弹丸撞击瞬间的弹道参数设定、弹孔图像在玻璃平面内的二维图像参数设定、相关角度的描述、计算抛物线轨迹与弹道轨迹朝向等一系列步骤,最终,研究出上述两类玻璃窗的弹道轨迹计算方法。研究表明,弹丸弹道飞行轨迹算法可以还原弹丸飞行的轨迹抛物线,作为现场弹道轨迹重建系统的核心算法使用,为开发弹打玻璃类案件的现场弹道轨迹重建系统提供了关键技术。     

Bayesian mixture modelling for glass refractive index measurement

Glass is a common type of physical evidence in forensic science. Broken glass recovered from a suspect may have similar physical characteristics to glass collected at a crime scene and therefore can be used as evidence. Statistical treatment of this evidence involves computing a measure of the weight of evidence. This may be done in a Bayesian framework that incorporates information from the circumstances of the crime. One of the most crucial quantities in this calculation is the assessment of the relative rarity of the characteristics of the glass, essentially the probability distribution used to model the physical characteristics of recovered glass. Typical characteristics used in casework are the elemental composition of glass and the refractive index measurement. There is a considerable body of scientific literature devoted to the modelling of this information. For example a kernel density estimation has been used to model the background population of glass based on the refractive index measurement and a multivariate Gaussian finite mixture model has been used to model the elemental composition of glass. In this paper, we present an alternative approach, the Dirichlet Process Mixture Model, to model the glass refractive index measurement in a Bayesian methodology. A key advantage is that using this method allows us to model the probability density distribution of refractive index measurements in a more flexible way.     

Tape Lift Sampling of Chemical Threat Agents

Commercial‐off‐the‐shelf (COTS) materials were evaluated as surface samplers for the Department of Homeland Security Chemical Forensics Program. The program helps evidence collectors identify trace chemical residues at incident scenes. COTS items are widely available, produced in large lots, and with strict controls. Chemical attribution signatures were collected from common surfaces. Eight tape lift candidates were considered, five were chosen based on performance and tested for analytical interferences and extraction efficiencies with 14 chemicals. Three products (duct tape, print lifters, command strips) were evaluated for uptake from common interior surfaces (glass, tile, ABS plastic). Duct tape provided highest recoveries across all surfaces. Even the most volatile analytes were detected in the ABS plastic samples (nondetections in others), regardless of tape lift material used. The porous plastic substrate provides better target retention than glass and tile surfaces. Forensic field operators should sample surfaces made of ABS plastic (keyboards, remotes, phones, etc.) whenever possible.     

高铁隧道内气动效应形成损坏痕迹特点分析

动车高速通过隧道时,运行车体推动的空气由于受到隧道壁的约束能形成能量很强的冲击气流,有时会造成一些设备设施损坏、脱落,进而危及高铁行车安全。这类事件发生后,铁路部门往往误以为是人为破坏,并以破坏案件进行上报。本文通过对特定动车行车事故的现场勘验、调查访问,分析了高铁隧道内气动效应对特殊位置设施造成损坏的过程及形成痕迹特点,准确认定了事件性质和事故发生原因,并对气动效应形成损坏痕迹和常见工具形成痕迹的区别进行了探讨。     

The Recovery of Latent Fingermarks from Evidence Exposed to Ionizing Radiation*

Abstract: Continual reports of illicit trafficking incidents involving radioactive materials have prompted authorities to consider the likelihood of forensic evidence being exposed to radiation. In this study, we investigated the ability to recover latent fingermark evidence from a variety of substrates that were exposed to ionizing radiation. Fingermarks deposited on common surfaces, including aluminum, glass, office paper, and plastic, were exposed to doses ranging from 1 to 1000 kGy, in an effort to simulate realistic situations where evidence is exposed to significant doses of radiation from sources used in a criminal act. The fingermarks were processed using routine fingermark detection techniques. With the exception of glass and aluminum substrates, radiolysis had a considerable effect on the quality of the developed fingermarks. The damage to ridge characteristics can, in part, be attributed to chemical interactions between the substrate and the components of the fingermark secretions that react with the detection reagents.     

Behavior of expelled glass fragments during projectile penetration and perforation of glass

Bullets striking common forms of flat glass with an orthogonal intercept angle result in a cloud of ejected glass fragments that are in concert with the exiting bullet's flight path. This is not the case with strikes at angles other than orthogonal. In these situations, the expelled glass fragments follow a very different course from that of the exiting projectile. This is both counterintuitive and a potential source of serious error in the evaluation and reconstruction of a shooting victim's position and orientation at the moment the victim was struck by a bullet that has passed through a nearby source of glass such as a vehicle side window or a window in a building. The flight path of the ejected glass fragments is, however, predictable and is dictated by the orientation of the plane of the glass opposite the projectile's impact site.In all cases, these expelled glass particles have considerable velocity and can produce pseudostippling of the skin in individuals located downrange of bullet-struck glass and near the projectile's exit site. The distribution and location of such pseudostippling and its relationship to the associated bullet hole in glass have important reconstructive value. A proper and reliable reconstruction of the victim's position in such cases will require the integration of scene information with the autopsy findings.     

The migration of fragments of glass from the pockets to the surfaces of clothing

During the last decade or so there has been some discussion in the forensic community in the United Kingdom concerning whether it is necessary to search the pockets for glass particles in garments attributed to suspects arrested for glass breaking crimes. The removal of this practice would help expedite the searching and recovery process since examining only the surfaces of clothing would reduce the cost of recovering glass evidence. However, it is believed by many scientists that some glass fragments originally acquired in pockets can migrate to the surfaces of clothing prior to examination by the forensic scientist. As glass fragments have been encountered in the pockets of garments during examinations of casework items in the LGC Laboratories, the implications of this change in practice needs to be assessed. Hence, the aim of this study was to investigate this possibility that fragments of glass migrate from a pocket of a garment to its surfaces during police and laboratory handling after a person is suspected of breaking glass during an offence. If this occurs to a significant extent then it could affect the evaluation of the glass evidence when using a Bayesian approach. Sixty fragments of glass were seeded into a pocket of a fleece jacket and a pair of denim jeans. Three experiments were performed; one examined a searching, recovery and blanking procedure, another examined the pre-laboratory 'handling' process of an item in an evidence bag, and the third experiment looked at the removal of an object from a pocket laden with glass and subsequent removal and packaging of the garment. Up to two (3.3%) fragments were recovered from the surfaces of the fleece jacket and the denim jeans via the searching, recovery and blanking procedure. Similar numbers were also recovered from the insides of the evidence bags. Up to four (6.7%) fragments were recovered from the surface of the fleece jacket and up to five (8.3%) fragments were recovered from the surface of the denim jeans after pre-laboratory 'handling'. Again similar numbers were recovered from the insides of the evidence bags. Comparable numbers to those from searching/recovery experiments were observed when garments were removed after taking an object from a pocket. In addition, up to two (3.3%) fragments were recovered from the object (a mobile phone). The findings show that some migration can occur particularly in the second experiment and therefore modification of the evaluation strategy may be required.     

Puncture wounds caused by glass mistaken for with stab wounds with a knife

Three cases are presented where fatal puncture wounds caused by broken glass were very similar to stab wounds inflicted by a knife with a single-edged blade. Thus, all three cases caused a murder investigation to be initiated. It could only be determined that these wounds had been caused by glass after a detailed forensic autopsy. In two of the three cases, the only evidence for this was the identification of glass fragments in the wounds. The importance of X-ray examinations is underlined because modern glass in common use is radiopaque. Glass fragments lodged in the wounds can reduce the loss of blood and thus, prolong the capacity to act despite severe injuries.