局部指纹内汗孔特征识别准确性研究

目的 探讨汗孔特征在局部指纹内识别的准确性,为汗孔特征的应用提供依据。方法 通过对四种承痕客体上遗留手印进行显现、汗孔标注、统计局部指纹内汗孔特征标识的正确率、错误率、漏标率,比较不同客体、不同显现方法对汗孔识别的影响。结果 局部指纹内汗孔识别的平均正确率为92.30%,平均错误率为7.70%,平均漏标率为7.39%,手印面积大小、承痕客体性质、显现方法以及人为因素对汗孔识别准确性有一定影响。结论 在一定条件下,小面积局部指纹内汗孔特征可以得到有效识别,且识别的准确性较高,汗孔特征识别准确性研究为利用汗孔特征辅助手印鉴定提供了依据。     

探析高分辨率指纹特定条件下三级特征的稳定性

目的探索油墨捺印指纹显现三级特征稳定性的影响因素,排除主观条件的影响。方法在最适宜的条件下,通过油墨捺印采集不同压力下的指纹样本,清晰地显出指纹三级特征,用高分辨率扫描仪扫描试验样本,保存指纹样本,最后分析了指纹汗孔、细点线、纹线形态、皱纹等三级特征的反映性及稳定性,确定其鉴定价值。结果油墨捺印法对三级特征的反映性不够理想,汗孔、纹线形态特征、细点线特征及皱纹在不同压力下的稳定性较差。其中,各个三级特征在轻压下的反映性及稳定性较为接近实际,捺印的压力越大则三级特征变形越大,甚至完全变形成为另外一种特征。结论所以如果将此法应用于指纹比对时,仍需进一步的研究与改进。     

微距摄影拍摄汗孔痕迹

汗孔检验是指纹检验的一项分支内容。汗孔形态、大小、密度、排列、布局等形量关系具有自身特点。汗孔检验与乳突线边缘特征检验、手型特征检验、褶皱纹线检验、以及乳突线细节特征检验,共同构成指纹形态学识别鉴定的完整体系。以往获取汗孔印痕,习惯思维是借助显微镜进行显微摄影。现场勘察或实验室里能否使用135型相机直接照相提取汗孔印痕,针对这一课题,作者选用了理光XR—10M相机,理光50mmF/1.7标准镜头,威达24mmF/2.8广角镜头,威达70—210mm为变焦镜头,威达2×增距镜,海鸥A型近摄接圈等常规模摄影器材,展开了尝试性探索试验。资料显…     

活体指纹采集方法应用初探

1 活体指纹采集方法是高科技的结晶指纹活体采集是集光、机、电及计算机技术于一体的高科技全新采集方法.用光电扫描或摄像技术直接采集人的指纹并存入计算机磁盘,该方法所采用的设备由专用扫描仪(或高分辨率高速线阵CCD摄像机),微机等构成.采用该设备可实时监测、控制被采集指纹,以获得高质量的指纹图像.活体指纹采集设备能方便、快捷、图文并茂地提取高保真,高清晰度的指纹图像,为有关部门建立指纹数据自动化提供了有利条件,符合现代化指纹信息系统的需要,被广泛应用于公安、保险、银行等多种行业,展示出广泛的应用前景.     

尸体与活体指纹微观细节特征的差异分析

目的比较尸体与活体指纹的微观细节特征差异,以帮助判断指纹的状态属性。方法用VSC-5000文检仪在放大15~30倍的条件下,观察比较尸体与活体指纹的微观细节特征。结果尸体与活体指纹的乳突纹线的边缘形态、宽窄及汗孔印等微观细节特征存在差异。结论指纹的微观细节特征是尸体与活体指纹种属鉴别的重要依据之一。     

指纹三级特征在指纹鉴定中的价值

国外有关指纹学的论著中将指纹特征的分类层级分为三级：一级特征即指纹线类型特征;二级特征即指纹线的宏观细节特征,如分歧、结合、起点、终点、小点、小棒、小钩、小眼、小桥以及罕见的交叉线、错位线、点线、节线等;三级特征即是指纹的微观细节特征,主要包括乳突纹线边缘形态、纹线宽窄、细点线和汗孔特征等[1].在指纹鉴定中常常遇到模糊、残缺、变形的疑难指印,这类指印的宏观特征点较少,如果按照常规的鉴定方法根据指纹的一级和二级特征则难以作出认定同一或否定同一的判断.而这类指纹的鉴定意见在刑事、民事案件的审判中又是十分重要的证据.此外,鉴定中有时还涉及伪造指纹的鉴别等等.为此,指纹三级特征在指纹鉴定中的应用价值也日益凸显,本文将针对此作如下讨论.     

利用CAFISNT系统进行远程网络查询案件

指纹系统的远程联网运行,给我市的刑侦工作注入了新的活力,标志着我市指纹资料的管理工作进入一个全新的发展时期。以下介绍笔者一年多以来运用CAFISNT系统进行远程网上检索比对工作的情况。1 指纹资料的广泛收集和及时建库是远程检索破策的前提 样本指纹的采集工作是整个指纹网络系统的基础和前提。由于这项工作涉及到全局许多部门,覆盖面广,工作琐碎,基层单位重视不够,因此指纹卡捺印质量不是很高。“巧妇难为无米之炊”,再先进的指纹系统,如果缺乏有效的指纹数据,也形同摆设;所以必须把相应的奖惩措施与指纹捺印采集的质与量联系起来,从制度上严把质量关,使指纹采集这一日常基础工作为大家所重视。     

警用活体指纹采集系统基本原理及技术创新

目的创立一种警用多个数字传感器同通道活体指纹采集系统。方法应用多个数字传感器定时同步控制技术、模拟无穷远成像技术、自适应采集参数控制、指位校准、内置专业模糊匹配算法等进行技术创新。结果有效提高活体指纹采集的成功率。结论该系统在实践工作中有广泛应用价值。     

间接免疫酶组化法检测人指纹ABO血型

建立一套测定人指纹 ABO血型的方法体系。运用间接免疫酶技术和免疫印迹技术 ,对指纹胶纸提取的指纹、银粉显现提取的指纹、直接转移至硝酸纤维素膜 (NC膜 )上的指纹、银粉显现转移至 NC膜上的指纹、“5 0 2”胶熏显转移至 NC膜上的指纹等进行 ABO血型检测。上述 5种方法采集的 2 12枚指纹 ,绝大部分能正确地检出 ABO血型 ,检出率为 90 %～ 93.8% ;未能检出的样本为非分泌型人指纹。应用间接免疫酶技术及免疫印迹技术测定人指纹的 ABO血型的方法具有特异性强、准确可靠、检测方便等优点 ,在法庭科学中易推广应用 ,并能发挥重要的作用     

计算机分离重叠指纹实验研究

目的探讨利用计算机分离重叠指纹方法的实用价值。方法对人工合成和现场采集的重叠指纹进行了大量实验研究,并得出了相关结论。结果计算机分离重叠指纹方法不仅应用范围广泛,操作技术简单,分离效果较好,且不破坏检材,是当前较有效的一种方法。     

The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry

Laser micropyrolysis gas chromatography-mass spectrometry is used for the analysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser microprobe to selectively target very small parts of the materials for GC-MS analysis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser radiation. The difficulty with the fibers demonstrates that a specific laser wavelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strongly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was detected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate individual molecular characterization (i.e., molecular fingerprinting). The integrity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be advantageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data.     

Identification of tiny and thin smears of automotive paint following a traffic accident

Three complementary methods in the order of stereomicroscopy, micro-FT-IR spectroscopy and solubility tests were used for the purpose of matching known and questioned paint samples in an auto accident case. Grayish green paint smears scattered on a silvery gray coated plastic bar were taken from a blue car and referred to as questioned samples. Green paint chips were collected as known samples from a green car. These were analyzed to determine whether the paint smears found in the blue car could have been the transfers from the green car. Although each of the three methods, when used alone, suffered from unequal bases for making comparison (i.e., layering whole paint vs. smeared paint), insufficient specificity of methodology and the interfering background coating beneath the smeared paint, the limitations were significantly relieved when three methods were used in combination. Based on the results presented in this report, the questioned grayish green paint smears collected from the blue car and the known green paint chips from the green car are of the same class of paint; that is, the possibility of the above stated paint transfers cannot be eliminated.     

红外差谱技术用于微量混合油漆的比对检验

对交通事故中的漆片检材进行同一物质比对时,某些情况下难以提取到单一的油漆碎片而是两辆车的油漆混合在一起,给物证比对带来困难。红外差谱技术具有辨别混合物中不同成分的功能,因此可应用于交通事故中混合油漆检材的比对检验。本文对一起交通事故的漆片检材,分别用三种方式提取、制样,用红外光谱仪进行分析,借助红外差谱技术对谱图进行处理,排除混合油漆的干扰。处理后得到的谱图与样本的谱图进行比对,结果显示两者主要官能团吸收峰位置、峰型、峰强度基本一致,可出具比对一致的结论。针对混合油漆检材的比对检验,红外差谱技术可提供支持。     

汽车罩光漆的ATR-FTIR法检验

目的通过对油漆样品罩光漆成膜物质的检验以区分不同汽车厂家的油漆样品。方法采用衰减全反射红外光谱法（Fourier Transform Infrared Spectroscopy Attenuated Total Reflection Spectroscopy,ATR-FTIR）研究15个汽车厂家提供的356份油漆样品的罩光漆成膜物质。结果在所有油漆样品中,丙烯酸漆出现的频率最高,氨基漆出现的频率最低;在所有厂家中,使用丙烯酸漆的厂家最多,使用氨基氨酯混合漆的厂家最少;在使用相同罩光漆的不同厂家的油漆样品中,通过比较红外谱图可以对样品进一步区分。结论 ATR-FTIR法能够在一定程度上区分不同汽车厂家的油漆样品,从而大大缩小侦查范围,对于涉车案件的快速侦破具有非常重要的作用。     

The random presence of glass and paint on the clothing and footwear of members of the general population: A US baseline survey at various seasons

This study assists the interpretation of glass and paint evidence by filling an existing gap in the background occurrence that reflects the socioeconomic and demographic circumstances in the United States. The collection was performed in a college US city (Morgantown, West Virginia) to determine the effect of the type of clothing worn at different seasons on the presence of glass and paint. Tape lifts and sole scrapings (1038) were collected from 210 participants and up to six clothing and footwear areas per individual. Glass fragments were analyzed via polarized light microscopy (PLM), refractive index (RI), micro-X-Ray fluorescence (μXRF), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), while paint specimens were examined by light microscopy and infrared spectroscopy (μFTIR). Higher occurrences of glass and paint were found in the winter season. The winter collection yielded 10 glass fragments and 68 paint particles, whereas the summer collection resulted in one glass fragment and 23 paint particles. The percentage of individuals with traces varied between seasons; 7% of individuals in the winter and 0.9% in the summer had glass, whereas 36% of individuals in the winter and 19% in the summer bore paint. Lastly, when considering the overall garment and footwear areas, glass was detected in 1.4% of the winter set, compared to 0.2% in the summer collection; paint was found in 9.2% of the winter collection, whereas only 4.2% was found in the summer set. There were no instances where both glass and paint were detected on the clothing and footwear of the same individual.     

显微光谱成像技术在汽车油漆截面检验中的应用

目的对汽车多层油漆的横截面进行分层和比对研究。方法运用显微光谱成像技术对收集的12个省市623个汽车漆片样本进行分层,并对截面结构相同或相似的油漆样本进行了区分。结果 623个油漆样本均可以分层,分析出漆层为两层及以上的油漆样本数占总数的87.26%;截面结构相同或相似的油漆样本能够多层同时区分。结论该方法具有科学及实用价值,检验结果可靠,可见光谱成像技术完全可运用拓展到微量物证的检验中。     

常见油漆稀料的GC／MS的检验及分类研究

目的对常用油漆稀料的检验分析方法及分类进行研究,并建立SPME-GC／MS对纵火案件中油漆稀料快速、灵敏、准确的分析方法。方法采用SPME-GC／MS法对5种不同型号品牌的常见油漆稀料进行分析。结果确定了样品处理方法和仪器分析最佳条件。实验的5种油漆稀料样本根据组分特征和结构特征的不同可归纳为4类。结论该研究结果可为纵火案件中油漆稀料残留物提供一种新的检验方法和检验依据。     

A survey of paint flakes on the clothing of persons suspected of involvement in crime

A survey was undertaken to determine the background level of paint flakes on the clothing of persons suspected of involvement in crime. The debris from 100 garments submitted for casework examination was studied and paint flakes recovered where present. Seventy two percent of garments bore one or more flakes. A total of 703 flakes were recovered; size, topcoat colour, and number and colour of any under-layers were recorded for each. The distribution of paint flakes on clothing surfaces and in pockets was also noted. Results were compared with the previously published survey of Pearson, May and Dabbs (1971). This survey provides scientists with an updated data set for reference when considering the strength of paint evidence.     

The Evidentiary Significance of Automotive Paint from the Northeast: A Study of Red Paint

This population study was conducted to assess the frequency of physical, microscopical, and chemical properties of automotive paint chips. Population studies of trace evidence provide valuable analytical data for criminalists to assess evidentiary significance. Two‐hundred automotive paint chips were collected from auto body shops from the Northeastern United States. All samples were analyzed using stereomicroscopy, brightfield, and polarized light microscopy. Red paints were targeted for further analysis using a sequence of modern instrumental techniques commonly used by forensic paint examiners: Fourier‐transform infrared (FT‐IR), Raman, and ultraviolet–visible (UV–Vis) microspectroscopy. The discrimination potential of each analytical method was evaluated by inter‐comparing the paint samples. Results demonstrated that macroscopic and microscopic properties were able to differentiate 99.995% of the population (one undifferentiated pair out of 19,900). When combined with either FT‐IR or UV–Vis microspectroscopy, all paints were differentiated. The results of this research lead to the conclusion that one would not expect to encounter two indistinguishable paint chips originating from different sources during the investigation of a single event.     

Survey of crowbar and household paints in burglary cases-population studies, transfer and interpretation

Experimental data useful for the interpretation of paint evidence recovered during burglary cases were obtained. A population study was carried out on 41 blue crowbars seized on suspects in Switzerland and 37 blue paints traces found at burglary scenes. Paint traces were also searched on the blades of 207 crowbars seized by the police in Switzerland and 24 white traces were analysed: these paints were analysed using infrared spectroscopy (FTIR) in order to estimate relative frequencies of each paint type. Simulated contacts were carried out between crowbars and painted wood in order to study the phenomenon of transfer and to evaluate the amount of paint transferred: a total of 198 simulations were carried out including individual, successive and cross transfer. The paint properties such as the chemical composition and its age influenced the amount of paint transferred. Cross transfer from the tool paint to the wood and vice versa was regularly observed. Moreover, secondary transfer of paint coming from the preceding wooden surfaces was also systematically observed: this could establish links between several burglary scenes and a suspected tool. A scenario of a burglary case involving the cross transfer between tool and household paints is proposed as a numerical example: the evaluation of such case was formalised using likelihood ratios based on the experimental data obtained.