从一起交通肇事案件浅谈油漆物证的提取和检验

油漆是交通肇事案件中最常见的物证,油漆物证的检验对于交通肇事逃逸案件的侦破尤为重要.对现场遗留漆片或被撞物品上附着油漆的检验,可以为案件侦破提供方向和线索;通过与嫌疑车漆片的比对,可以为证实接触事实提供证据. 本文根据一起交通肇事案件的物证检验鉴定过程,总结了油漆附着物检验的几点经验,供同行参考.     

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。     

交通肇事逃逸案件的查缉途径探究

交通肇事逃逸案件各要素具有自身的特点，侦破交通肇事逃逸案件既有有利条件世有不利条件。查缉途径一般有从肇事痕迹物证的检验、查证入手、从举报线索入手、从调查访问入手、从现场监控录像资料入手、从电子讯信息入手、从查控“阵地”入手、从协作入手等方面。本文指出选择查缉途径应综合考虑多种因素，这样有利于查缉工作的顺利开展。     

如何根据损伤痕迹检验分析交通肇事逃逸案件

在道路交通事故中,交通肇事逃逸事故是一种较为常见的类型,一般包括人-车碰撞事故和车-车碰撞事故。对于此类事故,通常需要借助对车体痕迹检验、人体衣物痕迹检验、微量物证检验、法医人体损伤检验、现场散落物整体分离痕迹检验等法庭科学技术以及运动学、动力学等物理学相关知识认定肇事车辆,判定车与车、车与人是否接触,推断接触部位及接触方式。     

交通肇事案件中纤维物证的光谱成像检验

纤维与人类有着非常密切的关系,是日常生活中不可缺少的物质。随着社会的发展,纤维在人类社会中的应用越来越广泛。如在交通事故中,由于受害者在与肇事车辆的碰撞过程中衣服上的纤维容易附着在肇事车辆上,因此纤维物证是交通事故中较为常见的物证之一。通过对交通肇事案件中纤维的比对检验，可以起到证实或否定肇事事实的作用。     

第一讲 物证检验常用仪器

物证检验在刑事侦查中具有重要作用。在我国,物证检验尚属一个有待进一步开发的领域。为了借鉴外国物证检验方面的研究成果,促进我国物证检验工作的开展,本讲座编译了国外有关物证检验的内容。其中包括:物证检验常用仪器、玻璃检验、泥土检验、金属检验、涂料检验、纤维检验和有关法医物证检验等。本讲座侧重于基本原理和基本方法的系统介绍,这无论对于理论研究还是实际工作都有一定的参考价值。     

电子物证检验

目的阐述电子物证检验技术的专业内容和组成,以及开展电子物证检验的作用和重要意义;方法研究美国、欧洲和国内电子证据及其检验鉴定的数据资料,结合国内物证检验技术发展现状和需求,论证电子物证检验技术;结果提出了电子物证检验定义、检验对象、技术方法、特点作用以及尽快在国内建立电子物证检验专业等观点;结论电子物证检验是关于识别、发现、提取、保存、恢复、展示、分析和鉴定电子设备中存在的电子信息(电子证据)的科学技术,其检验结果可以作案件侦查线索或法庭证据。开展电子物证检验可以有效提高犯罪侦查效率。     

红外照相显示掩盖字迹侦破一起交通肇事逃逸案

目前,交通肇事后逃逸案件时有发生,且呈上升趋势。在新形势下,利用先进技术检验手段,在办理此类案件中,可起到重要作用。近年来,我们利用撞擦痕迹、轮胎轧痕、分离物体、微量物证等技术手段为交警队确认嫌疑车辆,进行了一些检验鉴定。今年元月,我们又利用红外照相技术显示被掩盖字迹,为直接侦破一起重大交通肇事逃逸案起到了关键作用。 案情:1994年元月23日21时,在安阳市安楚公路12.5公里处,发生一起重大交通肇事,肇事车轧死一人,逃离现场。县公安局交警大队接报案后到达现场,经勘查访问,只了解到肇事车的行驶方向为从东向西,根据现场痕迹判断为客货车     

214例交通肇事逃逸案中涂料检验情况的统计分析

近年来,交通肇事逃逸案发生率不断上升,在这类案件中涂料是最常见的物证。笔者分析了214例案件中的涂料检验情况,现介绍如下: 1 成膜物质检验 214例案件中,认为涂料主要成分一致的有157起,认为有区别的有57起,分别占78％、22％,前者明显高于后者。这一方面是由于交警队对送检的嫌疑车已进行了一定的筛选,更重要的是受检验方法的限制,有些不是同一来源的涂料没能进行区分。     

纤维物证检验技术的现状及发展

本文概述了国内外纤维物证的发现、提取和检验方法及研究进展,并针对我国不少地区刑侦部门在现场勘查和物证检验中对纤维物证重视不够等问题,提出我国纤维物证研究应以现场发现方法、综合检验技术研究及数据库建设为主要方向。     

Forensic applications of infrared chemical imaging: multi-layered paint chips

This paper examines the potential of infrared chemical (hyperspectral) imaging as a technique for the forensic analysis of automotive paint chips in particular, and multicomponent (e.g., layered) samples in general. Improved sample preparation procedures for the infrared analysis of paint chips are detailed, with the recommendation that where mounting resins are chemically incompatible with the sample, it is better to mount and section the sample in a soft wax from which the sections can be removed and pressed into a KBr disk for transmission analysis. Infrared chemical images of multilayered paint chips have been successfully obtained, with the chief advantage over conventional infrared analysis being that thousands of infrared spectra are collected in a few minutes across the whole sample, at a spatial resolution of around 5 microm. As with conventional infrared spectroscopy, chemical species can be identified from their spectra, but the wealth of information available can be also extracted in a number of different ways that make multicomponent spectral (and hence chemical) comparisons between two samples easy to visualize and understand. In one approach, the infrared chemical images of two paint chips being compared side-by-side can be viewed as a "movie," in which each frame is an intensity map of the two samples at a given wavenumber (frequency) value. In another approach, the spectra (pixels) in the image files are classified into chemically similar groups, resulting in a "cluster" image that makes it possible to simultaneously compare all of the layers in two paint chips. These methods are applicable to other multicomponent samples, and also to other chemical imaging techniques.     

傅里叶红外光谱技术在法医学脑挫裂伤鉴定中的应用展望

脑挫裂伤是常见的一类颅脑损伤,单纯的组织病理学技术可能难以早期发现及精确诊断。傅里叶变换红外面扫描成像技术(FTIR-mapping)是病理学研究领域的新技术,因其结合了傅里叶变换红外光谱、红外显微镜技术以及面扫描成像技术的特点,具有测定方法简便、对样本无损、灵敏度高、准确、直观等优点,突破了传统技术的局限,能检测出发生了物质数量、结构以及构象变化但缺乏明显形态学变化的脑挫裂伤,从而实现早期精准地诊断脑挫裂伤。FTIR-mapping虽已能绘制某些损伤组织的红外光谱病理图像,但其在法医病理学中的价值有待全面深入开发。本文综述了脑挫裂伤的法医病理学研究进展以及傅里叶变换红外面扫描成像技术在法医病理学中的应用。     

Comparison of transmission and internal reflection infrared spectra of cocaine.

Comparing the infrared transmission spectrum of cocaine HCl to its attenuated total reflection (ATR) spectrum has raised questions about the use of ATR spectra for forensic drug analysis. Whenever infrared spectra are collected using different modes or sample preparation methods, small variations in peak intensity ratios or peak positions are possible. These variations in infrared spectra are small and do not interfere with qualitative analysis, but they can cause confusion when unrecognized as normal effects of the different spectroscopic techniques. Comparison of the absorption and ATR spectra of cocaine hydrochloride illustrates the type of differences that can be expected. These differences are explained by the fundamental differences in the collection techniques. For the best quantitative results, only spectra collected by the same technique should be compared.     

In situ identification and analysis of automotive paint pigments using line segment excitation Raman spectroscopy: I. Inorganic topcoat pigments

Several applications of Raman spectroscopy in the forensic sciences have recently been demonstrated, but few have involved the analysis of paints. Undoubtedly, this is a reflection of the sample degradation problems often encountered when a visible or near-infrared laser is focused on a light-absorbing matrix. In this study, a dispersive CCD Raman spectrometer (785 nm) was used in a configuration which collected scattered light from an excitation region 3 mm long and 80 microm wide, instead of from a focused spot. Sample degradation was not observed, and Raman spectra of automotive paints of all colors were readily obtained. Most of the paints analyzed were U.S. automobile original finishes (1974 to 1989) from the Reference Collection of Automotive Paints, and the inorganic pigments examined were those which had been identified previously by infrared spectroscopy in finishes from this collection. Prominent peaks of rutile were observed in Raman spectra of light-colored nonmetallic finishes for both monocoats and basecoat/clearcoat systems, and the rutile peaks are readily distinguished from those of anatase. The lead chromates (Chrome Yellow, Molybdate Orange, and silica-encapsulated versions of the two) are the strongest Raman scatterers among the pigments examined, and Chrome Yellow was identified by Raman spectroscopy in several yellow and orange nonmetallic monocoats for which infrared absorptions of this pigment were not observed. Raman spectroscopy also provides an unequivocal means to distinguish Chrome Yellow from Molybdate Orange. This is particularly helpful for the analysis of paints containing light pigment loads or encapsulated pigments since the two formulations cannot be differentiated by infrared spectroscopy in such cases. The iron-containing pigments, ferric oxide, hydrous ferric oxide, and Prussian Blue, are relatively weak Raman scatterers, but peaks of hydrous ferric oxide and Prussian Blue were observed in spectra of paints containing heavy pigment loads. Because no sample preparation is required. Raman spectroscopy provides an excellent means to rapidly screen reference panels for the presence of certain pigments, and some examples of the differences in Raman spectra which occur for paints having similar colors are presented.     

红外光谱法用于安钠咖中咖啡因和苯甲酸钠快速定性和定量分析

目的建立安钠咖样品中咖啡因和苯甲酸钠快速定性和定量分析的红外光谱方法。方法采用高纯度咖啡因和苯甲酸钠混合制样的方法制备定性和定量建模样品,通过分析混合样品的红外光谱图,确定安钠咖样品中咖啡因和苯甲酸钠的特征吸收峰。采用偏最小二乘法(partial least squares,PLS)建立红外光谱定量模型。结果通过分析17个咖啡因和苯甲酸钠混合样品(咖啡因纯度范围10%~80%)的红外光谱图,确定了咖啡因的特征吸收峰为1698、1650、1237、972、743、609cm-1;苯甲酸钠的特征吸收峰为1596、1548、1406、845、708、679cm-1。将所有特征吸收峰均检出作为阳性判断依据时,48个安钠咖缴获样品中咖啡因和苯甲酸钠的阳性检出率均为100%。咖啡因PLS定量模型的线性范围为10%~80%,决定系数(R2)为99.9%,交叉验证均方差(root mean square error of cross validation,RMSECV)为0.68%,预测均方差(root mean square error of prediction,RMSEP)为0.91%;苯甲酸钠PLS定量模型的线性范围为20%~90%,R2为99.9%,RMSECV为0.91%,RMSEP为1.11%。配对样本t检验结果显示,高效液相色谱法和红外光谱法的测定结果差异无统计学意义。采用所建立的红外定量方法分析48个安钠咖缴获样品,咖啡因的纯度为27.6%~63.1%,苯甲酸钠的纯度为36.9%~72.3%。结论采用红外光谱法对安钠咖样品中的咖啡因和苯甲酸钠进行快速定性和定量分析,可提高检验鉴定效率、降低检验成本。     

显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。     

Variation of the amide I and amide II peak absorbance ratio in human hair as measured by Fourier transform infrared spectroscopy

Human scalp hair samples were examined by Fourier transform infrared spectroscopy and the ratio of the amide I to amide II band absorbances was determined. The effects of hair oxidation, color, age of sample, and sex of source were examined. Scalp hair from 98 individuals was also analyzed. While there were differences in the amide absorption band ratios, these were difficult to relate to the individualization of the hair samples and did not appear to have a sufficient discriminatory value for routine forensic use.     

Structural determination of the principal byproduct of the lithium-ammonia reduction method of methamphetamine manufacture

One common method of illicit methamphetamine manufacture utilizes an alkali metal, typically lithium, and liquid ammonia to chemically reduce ephedrine or pseudoephedrine to form methamphetamine. This method is often referred to as the lithium-ammonia reduction method or the Birch reduction method. While the hydroxyl group of ephedrine is more reactive than the aromatic ring, excess alkali metal and the presence of a proton source allow the formation of a cyclohexadiene byproduct not found in samples of methamphetamine produced from other manufacturing methods. A sample enriched in this byproduct was generated and characterized using nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectrophotometry, and ultraviolet (UV) spectrophotometry. The chemical structure of this byproduct was determined to be 1-(1',4'-cyclohexadienyl)-2-methylaminopropane (CMP).     

The characterization of automobile body fillers

Body fillers are sometimes encountered with paint evidence from hit-and-run accidents. Little forensic research has been conducted and published on the subject since 1986. The objective of this study was to determine if chemical and physical differences in body fillers from various manufacturers existed and could be identified. Thirty-three samples of light-weight automobile body fillers and spot putties were obtained. The fillers and putties were compared using light microscopy, infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), and pyrolysis gas chromatography (pyGC). Results from fourier transform infrared spectroscopy analysis placed the samples into five groups and differentiated six samples. Light microscopy placed the samples into one of five color groups. PyGC placed the samples into three groups and differentiated one sample. SEM-EDX placed the samples into four groups and differentiated 13 samples. Using these analysis methods, 19 of the 33 samples could be discriminated. The best discriminatory tool was found to be SEM-EDX.     

Infrared Imaging of the Crime Scene: Possibilities and Pitfalls

All objects radiate infrared energy invisible to the human eye, which can be imaged by infrared cameras, visualizing differences in temperature and/or emissivity of objects. Infrared imaging is an emerging technique for forensic investigators. The rapid, nondestructive, and noncontact features of infrared imaging indicate its suitability for many forensic applications, ranging from the estimation of time of death to the detection of blood stains on dark backgrounds. This paper provides an overview of the principles and instrumentation involved in infrared imaging. Difficulties concerning the image interpretation due to different radiation sources and different emissivity values within a scene are addressed. Finally, reported forensic applications are reviewed and supported by practical illustrations. When introduced in forensic casework, infrared imaging can help investigators to detect, to visualize, and to identify useful evidence nondestructively.