对暗视场显现指印汗孔细节特征的初步研究

在指印鉴定工作中,利用汗孔细节特征对指印进行同一认定在国外司法鉴定领域已有应用,但在实际案件中,由于汗孔细节特征的发现和提取较为困难,同时对汗孔的分类、命名、标示等又存在一些没有解决的问题,目前在我国刑事技术领域还没有得到应用。文章采用一种常用的配光方法———暗视场照明方法,显现光滑平面玻璃上汗潜指印的汗孔细节特征,并对实验中影响汗孔细节特征形成的部分因素进行了初步研究。     

Detection of pretreated fingerprint fluorescence using an LED-based excitation system

Abstract:  Optimization of a light emitting diode (LED)-based excitation system for the detection of pretreated fingerprint fluorescence is described. Fluorescent ridges can usually be excited by irradiation with forensic light sources such as xenon arc lamps or quartz-halogen lamps with high-power output and suitable filters. However, they are too expensive for many crime laboratories in smaller organizations. We concentrated on LEDs which have advantages over conventional light sources in that they are simpler and of lower cost, but the power output and quality of each individual LED unit is not sufficient for the detection of weak fluorescent ridges. To resolve this subject, blue and green LED arrays composed of ninety LED units were adopted and suitable low pass filters for them were designed. An experimental system, consisting of blue and green LED arrays with the suitable low pass filters for illumination, high pass filters for viewing, a digital camera and a computer, was tested. The fluorescent images of cyanoacrylate ester fumed/rhodamine 6G stained fingerprint on white polyethylene sheet and weak fluorescent ridges of ninhydrin/indium chloride treated fingerprint on white paper were successfully detected and photographed. It was shown that the improvement of LED beam in intensity and quality can compensate the disadvantages, resulting in well-contrasted images.     

基于数据仓库与数据挖掘的自动指纹识别系统的探讨

通过对已有自动指纹识别系统的分析、研究 ,针对目前的自动指纹识别系统存在的建库速度慢 ,采集速度慢 ,错、漏率高 ,匹配效率差等缺陷 ,探讨了基于数据仓库和数据挖掘的自动指纹识别系统。     

油红O显现手印配方中各物质的作用验证

目的研究油红O显现手印配方中各物质的作用及其对显现效果的影响。方法对配方中的主要成分进行定性、定量实验来分析、考察实验结果。结果油红O粉末的颜色与显出的手印纹线颜色关系较大,溶液中的氢氧化钠关系着显出的手印纹线与背景的反差。结论 Alexandre Beaudoin公布的配方稳定、显现效果好,值得在实践工作中推广。     

DNA in the Criminal Justice System: The DNA Success Story in Perspective,

Current figures on the efficiency of DNA as an investigative tool in criminal investigations only tell part of the story. To get the DNA success story in the right perspective, we examined all forensic reports from serious (N = 116) and high‐volume crime cases (N = 2791) over the year 2011 from one police region in the Netherlands. These data show that 38% of analyzed serious crime traces (N = 384) and 17% of analyzed high‐volume crime traces (N = 386) did not result in a DNA profile. Turnaround times (from crime scene to DNA report) were 66 days for traces from serious crimes and 44 days for traces from high‐volume crimes. Suspects were truly identified through a match with the Offender DNA database of the Netherlands in 3% of the serious crime cases and in 1% of the high‐volume crime cases. These data are important for both the forensic laboratory and the professionals in the criminal justice system to further optimize forensic DNA testing as an investigative tool.     

亮绿SF溶液增强红色光滑客体表面潜血手印技术研究

目的探索一种实验室和犯罪现场上均可使用的红色光滑表面上血潜手印新型显现技术。方法把0.2g亮绿SF溶解到容积为200m L盛有5m L蒸馏水的烧杯中,然后加入0.2g正四丁基碘化铵、93m L无水乙醇,使用玻璃棒搅拌,充分溶解后,最后加入盐酸2m L形成绿色透明溶液作为显现液,采用精细喷雾器喷涂客体增强红色光滑面潜血手印,潜血手印增强后,照相提取后并对局部放大观察效果,研究其对红色光滑表面潜血手印的增强效果。结果对遗留手印进行了批量显现与统计分析,0.2%的亮绿SF酒精显现液对红色客体表面潜血手印的反应极其敏感,实验室条件下潜血手印样本显现率可达100%,显出的手印纹线清晰连贯,反差明显,无颜色背景,且局部放大能够有效显示出纹线的细节特征。结论 0.2%的亮绿SF显现液能有效增强红色光滑客体表面潜血手印,反差极其明显,可以作为红色光滑客体表面潜血手印增强试剂。     

京尼平序列显现手印方法研究

目的考察京尼平溶液显现手印的灵敏度,并探索DFO→京尼平→茚三酮方法联用显现纸张上潜在手印的效果。方法通过使用京尼平溶液对同一手印样本进行一次、两次和三次浸泡处理,考察浸泡次数是否会影响显现效果;通过对京尼平→茚三酮、茚三酮→京尼平,京尼平→DFO和DFO→京尼平方法的组合设计方案与每种方法的单独使用进行比较研究,考察序列显现方法对显出手印的影响。结果单用京尼平溶液对同一样本进行多次浸泡在自然光和荧光模式下都不会明显增强手印的显现效果,DFO方法先于京尼平、京尼平先于茚三酮使用都能起到增强手印纹线的效果。结论京尼平方法显现手印灵敏度较高,DFO→京尼平→茚三酮方法联用可以进一步提高手印的显出率。     

一次手印鉴定引发的思考

近期,我们受理了一起特殊的手印鉴定。此前该手印已有肯定与否定两种截然相反的鉴定结论,鉴定委托人又不能提供检材和样本原件,只将相关的照片送检。在检验过程中,我们经过观察分析、实验验证、计算机图像处理等过程,弄清了手印的本质,做出了科学、客观的结论。     

论数据挖掘在预防小区犯罪中的应用

数据挖掘是指从数据库或数据仓库中提取隐含的、未知的及有潜在应用价值的信息或模式。数据挖掘技术应用于预防小区犯罪,采用CRISP-DM方法论,通过数据理解、数据准备、模型选择、建立模型、训练模型、评估模型等流程,可以对犯罪分布区域、犯罪分子惯用手段、犯罪行为特征、受害人特征、受害人群识别等进行分析,识别高犯罪率的小区及犯罪特征。     

依据手足印推算身高体重的可行性研究

目的探讨身高、体重与足迹、手印长宽的关系,有助于利用犯罪现场的手印、足迹推断遗留人的身高与体重。方法通过足迹、手印的捺印和测量,大量地收集样本足迹、手印与身高、体重等数据,借助SPSS数理统计软件,进行一元线性回归分析。结果分别建立了由左右足迹、手印全长、掌宽推算身高与体重的十个一元线性回归方程,并对依据左、右侧指标分别推算结果的可靠性进行比较研究。结论可利用回归法由足迹、手印来推算身高、体重。在左右两侧足迹、手印都可利用的情况下,推断身高时应优先选用右侧;推断体重时应优先选用左侧。