电气绝缘胶带上的指纹显现方法探讨

电气绝缘胶带在犯罪现场出现和使用的频率不断增多,特别是一些以电起爆装置起爆的爆炸案件中,电气绝缘胶带使用的几率更高。这类案件破坏性大,现场物证遗留少。电气绝缘胶带上潜在指纹的显现和提取,显得尤为重要。本文作者在实践中针对电气绝缘胶带胶面上指纹的显现做了长时间的探索,在现有技术的基础上,摸索出了一些较为有效的方法,取得了一些进展。     

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...     

腐败餐厨油污纸屑上DNA检验1例

接触类生物检材因其DNA含量少、污染严重、PCR抑制物多、DNA检验成功率低一直是法医DNA检验的难点之一[1,2]。特别是餐厨纸屑等非常规接触类生物检材,在气温较高,气候潮湿的环境极易腐败。本文通过对腐败餐厨油污纸屑的DNA检验,得到一男性常染色体和Y染色体DNA结果,经数据比对分析,锁定犯罪嫌疑人,成功助破尘封21年之久命案。     

浅议笔迹特征比对表

笔迹鉴定的检验方法是特征比对,即通过分别检验,在找出检材字迹和样材字迹各自书写特征的基础上进行比对和综合评断,继而作出认定同一或否定同一的鉴定结论.因此,特征比对表是鉴定结论的“根据表”和“证据表”;是综合评断的“调查统计表”;是检验人员观察字迹的“感悟表”;是检验程序中的“首道工序表”。本文在阐述特征比对表重要性的基础上,对制作特征比对表的多种方式方法及其优缺点,以及如何寻找和标识特征谈了一些个人的认识和体会。     

涉爆案件中烟火剂的检验

目的　建立涉爆案件中烟火剂的快速、准确的检验方法。方法　以扫描电镜 /能谱仪分析为主 ,红外光谱分析为辅 ,对爆炸装置尤其爆炸残留物中的烟火剂进行形态和成分分析。结果　对烟火剂原体的检验快速、准确 ,通过比对分析可确定烟火剂的来源 ,对爆炸残留物中的烟火剂进行准确定性。结论　该方法对各种检材中的烟火剂检验稳定性好、准确率高 ,且操作简便 ,具有很强的实用性     

手印鉴定中接合比对检验法的应用研究

乳突纹线模糊、重叠或细节特征不清的手印,用常规方法进行比对检验有较大难度。一些线条状特征却可能在手印中得到较好的反映,它们也具有较强的特定性和较好的稳定性,可用来进行比对检验。运用接合比对检验法检验手印中的线条状特征,有利于提高手印的检验价值和利用率。     

调和汽油的GC-MS检验与区分

调和汽油在涉火案件中出现的频率逐渐增加,其特殊的组成可能对成分研判造成干扰。为准确识别汽油组分,区分不同来源的调和汽油,本文依托气相色谱–质谱（GC-MS）检验了部分典型调和油品,分析了相关样品的谱图特征并进行归类。结果表明,案件中常见的调和油品按照谱图主要特点可划分为添加剂异常、异构烷烃异常、直链烷烃异常和多组分异常四类。其中前两类对汽油及其残留物鉴定基本不构成干扰,而直链烷烃异常类油品可能引起误判,多组分异常类油品则不宜轻易下汽油结论。该研究结果对特殊调和汽油及其残留物的检验鉴定有一定的指导意义,对于涉火案件中汽油的比对分析和来源推断具有实战应用价值。     

车辆碰撞痕迹的同一性认定

目的判断车辆是否发生过碰撞和怎样碰撞。方法应用痕迹检验方法对车辆的痕迹进行检验分析比对。结果通过车辆痕迹检验总结出车辆碰撞形态技术鉴定的具体方法。结论判断车辆是否发生过碰撞和怎样碰撞可以从车体痕迹、人体痕迹、微量物证及轮胎路面痕迹等方面来进行判断。     

一种基于动态比对表的步态特征检验方法

目的建立使用动态比对表检验步态等人像运动特征的具体方法,为人像同一性鉴定中的动态特征比对提供方法和依据。方法从视频采集、预处理、特征提取、识别判断等流程出发考察现有的步态自动识别方法,并依据人像鉴定的实际需求进行分析。结果动态比对表制作应当依照检材、样本采集、归一化处理和制作、标识与输出等步骤,并考虑步态周期、视频参数等制作细节。结论使用动态比对表对人像运动特征进行考察有助于特征的展示,能够成为鉴定人进行人像鉴定的有效辅助手段。     

胶带的红外光谱检验

目的建立胶带的种类检验、方法。方法应用傅利叶显微红外光谱仪,分别对胶带的胶质、基质(基材)及整体(胶质和基质同时存在)进行检测分析。结果不同种类胶带,红外吸收图谱存在差异,相互间图谱匹配率不同。通过比对分析,可对不同种类的胶带进行鉴别。结论该方法检验胶粘带(胶带),检材用量少、结果准确,操作简便,具有很强的实用性。     

Use of nitrogen cryogun for separating duct tape and recovery of latent fingerprints with a powder suspension method

Duct tape is sometimes recovered as physical evidence in crimes. The purpose of this study was to determine the quality of latent prints on the adhesive and non-adhesive surfaces of duct tape samples that were separated using three methods. Three hundred donor fingerprint impressions were deposited on duct tape. Sections of duct tape were affixed to sections of cardboard and a fingerprint placed on the non-adhesive surface of the tape. A second layer of duct tape was prepared and a fingerprint placed on the adhesive side of the tape and then the tape was affixed to the piece of tape on the cardboard. After a 24-h period, the samples were separated using gradual force, liquid nitrogen applied with a cryogun and an adhesive neutralizer to separate the layers of tape. The recovered fingerprints were processed with a fingerprint powder suspension method. The recovered fingerprint images were evaluated and rated as +1, +2, or +3. The liquid nitrogen spray separation method yielded the highest number of +3 prints.     

Enhancing contrast of fingerprints on plastic tape

Many of the currently available fingerprinting methods have limited ability to visualize fingerprints on plastic tape without expensive equipment or significant handling of the sample. This is especially true for visualizing fingerprints on black electrical tape. This study sought a hands-off method to produce easy visualization of fingerprints on different types of plastic tape, including black electrical tape, without the need for expensive equipment. The methods selected were to sublime disperse dyes into the tape, both with and without the fuming of cyanoacrylate, everywhere except for where the fingerprint was applied. The resulting color contrasts provided enough differentiation to visualize fingerprints on plastic tape under ambient light. Sequential fuming with cyanoacrylate followed by disperse dyes provided the best visualizations on all tapes, and cyanoacrylate followed by disperse yellow 211 clearly visualized fingerprints on black electrical tape.     

Analysis of pressure sensitive adhesive tape: I. Evaluation of infrared ATR accessory advances

Attenuated total reflection (ATR), also known as internal reflection spectroscopy (IRS), is a forensically accepted method for infrared (IR) analysis of pressure sensitive adhesive tapes. Advancements of ATR accessories in the last decade have provided the forensic examiner several ATR methods to choose from. These accessories offer a variety of ATR crystal choices with a variety of prices and capabilities. Four different types of pressure sensitive adhesive tapes including duct tape, electrical tape, packaging tape and office tape have been used to compare six different ATR methods. Each of the methods tested offers both benefits and limitaltions which must be considered for the type of sample to be analyze. The intent of this paper is to assist the reader in better understanding ATR techniques, the many differences among currently available ATR accessories and how the method is applied to the analysis of pressure sensitive adhesive tape.     

掺杂Cd的水溶性荧光ZnSe/MPA量子点显现胶带手印方法

目的探索水溶性荧光量子点溶液——掺杂镉的硒化锌（ZnxCd（1-x）Se）对胶带手印的显现方法。方法以巯基丙酸（MPA）为修饰剂合成了掺杂Cd的水溶性荧光ZnSe/MPA量子点,利用它显现水浸胶带及粘连胶带上的油汗指印,并在365nm下拍照成像。结果良好的显现出水浸胶带上的指印以及粘连胶带上的指印。与常规方法相比,优势更为明显。结论水溶性荧光量子点ZnxCd（1-x）Se溶液显出的指印纹线细腻流畅,在法庭科学领域具有很好的应用前景。     

The Use of Adhesive Tape for Recovery of DNA from Crime Scene Items

Abstract: The selection of the appropriate method of collection of biological material from crime scene items can be crucial to obtaining a DNA profile. The three techniques commonly used for sampling items are: cutting, swabbing, and taping. The tape sampling technique offers an advantage, in that it enables the collection of a potentially highly informative source of DNA, shed epithelial cells, from selected areas on crime scene items (the inside fingers of a glove, for instance). Furthermore, surface collection of biological material by taping reduces co‐sampling of known PCR inhibitors such as clothing dyes. The correct choice of tape for crime scene item sampling is important. Not all tapes are suitable for biological trace evidence collection as well as DNA extraction. We report on one tape that met both these criteria. Three different cases are presented which demonstrate the usefulness of adhesive tape sampling of crime items. Finally, the advantages of the tape collection technique are discussed and guidelines for preferred areas of tape sampling on various casework items are presented.     

Recovery of Trace DNA on Clothing: A Comparison of Mini‐tape Lifting and Three Other Forensic Evidence Collection Techniques

Trace DNA is often found in forensic science investigations. Experience has shown that it is difficult to retrieve a DNA profile when trace DNA is collected from clothing. The aim of this study was to compare four different DNA collection techniques on six different types of clothing in order to determine the best trace DNA recovery method. The classical stain recovery technique using a wet cotton swab was tested against dry swabbing, scraping and a new method, referred to as the mini‐tape lifting technique. Physical contact was simulated with three different “perpetrators” on 18 machine‐washed garments. DNA was collected with the four different DNA recovery methods and subjected to standard PCR‐based DNA profiling. The comparison of STR results showed best results for the mini‐tape lifting and scraping methods independent of the type of clothing. The new mini‐tape lifting technique proved to be an easy and reliable DNA collection method for textiles.     

Identification of pressure-sensitive adhesive polypropylene tape

Identification of colorless, transparent, pressure-sensitive adhesive polypropylene tape (PP tape) was performed using infrared absorption spectrometry (IR) and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to determine the pressure-sensitive adhesive. Twenty different products of colorless, transparent PP tapes were examined in this study, and the results of analysis of IR spectra and Py-GC/MS were classified into twelve groups. In addition, the tapes were classified into 14 groups on the basis of IR measurement of release agent present in the backside. The results indicate that colorless, transparent PP tapes can be distinguished in terms of manufacturer, thereby demonstrating that this method of identifying colorless, transparent PP tape is effective. Moreover, the method was applied to the analysis of an actual forensic sample.     

Visualising latent DNA on tapes

This study reports a simple method for visualising and screening latent DNA on tapes using a Diamond™ dye (DD) staining process followed by visualisation using a portable fluorescence microscope. Ten types of tapes were tested, which include those used currently by forensic laboratories for tape-lifting. All ten types were tested for: 1) their auto-fluorescence, 2) properties when stained with DD using three different DD solutions, and 3) PCR inhibition through a direct STR amplification technique. No background fluorescence was noted viewing four types stained with 20 x DD diluted with 0.01% Triton-X. Clear tape (Sellotape®), DNA-free tape (Lovell Surgical Solutions) and brown packing tape (Packmate™) did not inhibit direct STR amplification, while the other six types showed the inhibition of the PCR. The three tapes were selected to assess their cellular material recovery efficiency by comparing the number of stained cells within an entire fingermark before and after tape-lifting. Tape-lifting was performed either once, twice or ten times. The DNA-free tape (Lovell) used in many forensic laboratories gave poor recovery compared to the clear tape (Sellotape®) and brown packing tape (Packmate™). This simple visualising technique allows the cell location to be recorded, and only the area of tape where cells are present to be removed for DNA typing. The process is a simple and effective triage procedure that reduces the processing of tape-lift samples where there are no cells present.     

Paint and tape: collection and storage of microtraces of paint in adhesive tape

The collection and preservation of microtrace evidence with the aid of an adhesive tape is a method of choice in forensic science. This technique is rapid and easy and allows the concentration of microtraces on a carrier, which facilitates further investigations in the laboratory. Adhesive tapes are currently used to secure microtraces of fibers and glass, but hardly for traces of automotive paint and other lacquers for fear of interference with the analysis of binders. A collection of automotive paint consisting of original and repair lacquers collected by tape has been evaluated. After various times of storage within the tape, these samples were compared with untreated references by microscope FT-IR and microspectrophotometry (MSP). Another set of paints was collected in 1984, stored within the tape until 1995, and examined the same way. About 170 layers of lacquer with various types of binder were examined. With the exception of one clear lacquer no difference between treated samples and references was detected. This small difference observed could be correlated to the exposure to xylene (extractant) and was not caused by the storage within the adhesive tape.