Examination of the steps leading up to the physical developer process for developing fingerprints

This is a systematic study that examines several acid prewashes and water rinses on paper bearing latent prints before its treatment with a silver physical developer. Specimens or items processed with this method are usually pretreated with an acid wash to neutralize calcium carbonate from the paper before the treatment with a physical developer. Two different acids at varying concentrations were tested on fingerprints. Many different types of paper were examined in order to determine which acid prewash was the most beneficial. Various wash times as well as the addition of a water rinse step before the development were also examined. A pH study was included that monitored the acidity of the solution during the wash step. Scanning electron microscopy was used to verify surface calcium levels for the paper samples throughout the experiment. Malic acid at a concentration of 2.5% proved to be an ideal acid for most papers, providing good fingerprint development with minimal background development. Water rinses were deemed unnecessary before physical development.     

DNA profiling from heroin street dose packages

A large amount of heroin street doses are seized and examined for drug content by the Israel police. These are generally wrapped in heat-sealed plastic. Occasionally it is possible to visualize latent fingerprints on the plastic wrap itself, but the small size of the plastic item and the sealing process makes the success rate very low. In this study, the possibility of extracting and profiling DNA from the burnt edge of the plastic wrap was investigated. The idea was based on the assumption that epithelial cells might be trapped during the sealing process. The results show that there are sufficient quantities of DNA deposited at the "amorphic" burnt edges of sealed street doses for DNA profiling to be carried out. A controlled experiment using a known donor was performed. This subject carried out sealing of "street drug" packages and consequent DNA extractions were performed to show that known DNA profiles could be recovered from such packages, as a result of handling by the "packer." "Square-like" burnt edges did not yield DNA profiles, probably because of differences in the sealing process. It was also shown that DNA could be recovered from the plastic wrap itself and not only from the amorphic burnt edges. As heroin dealers and drug users are often involved in other crimes and run-ins with the law, the effective extraction and addition of their DNA profiles from such items of evidence to the newly established DNA database in Israel provides new avenues in the continued fight against crime and drug traffickers.     

卫生纸上汗潜手印显现方法比较研究

目的通过比较实验来探寻卫生纸上汗潜手印的最佳显现方法,为实际工作提供指导性建议。方法选择市面上常见的四种卫生纸,在每种卫生纸上制作汗潜指印实验样本,分别将茚三酮溶液浸泡法与茚二酮溶液浸泡法、茚二酮溶液浸泡法与茚二酮溶液超声雾化法、茚二酮溶液超声雾化法与(对)-二甲(替)氨基肉桂醛(DMAC)显现纸冷熏法、茚二酮溶液浸泡法与红外加热显现法、茚二酮溶液超声雾化后加热显现法与室温显现法进行两两比较,分析显现效果。结果茚二酮显现的灵敏度和质量均优于其他几种方法,特别是超声雾化后室温显现,既能很好地显现手印又不影响后期的DNA检验。结论采取茚二酮超声雾化室温条件显现方法显现卫生纸上的汗潜手印具有显现效果好、设备条件要求低、操作性强的特点,在实际案件中可以借鉴应用。     

Research on the local regional similarity of automatic fingerprint identification system fingerprints based on close non-matches in a ten million people database—Taking the central region of whorl as an example

The local regional similarity of fingerprints has always been a hot issue in the field of fingerprint research. With the increasing size of ten-print databases, the appearance of close non-matches (CNMs) in automatic fingerprint identification system (AFIS) candidate lists has attracted increasing attention from forensic science departments worldwide. In this study, three categories (high-, medium-, and low-level) of standards for CNMs were established and 60 whorl samples were marked with different numbers of minutiae to explore the occurrence and influencing factors of CNMs in AFIS candidate lists based on a ten million people database. The results showed that all prints could be found with their corresponding CNMs. The average occurrence rate of CNMs for every query was 52.7% in the top 100 lists, and the most similar CNM was exactly the same in the local area of 12 coincidence points. CNMs appeared more in the middle and lower parts of the central region of the whorl. Moreover, shorter C2C distances and the same finger number and hand led to more CNMs being inspected. CNMs with higher similarity required a more extensive regional area and smaller minutiae density. We concluded that CNMs have a high occurrence rate in large-scale databases and many factors are closely related to them. Fingerprint examiners and researchers need to strengthen their understanding of CNMs to avoid the occurrence of misidentification like the Madrid bombings.     

利用加氨水催化法提取和拍照具有一定渗透性客体上的汗液手印

刑事案件现场经常遗留一些具有一定渗透性的客体，如丝绸、橡胶、皮革等，上面留有汗液指纹。由于汗液的挥发性和客体的渗透性，部分的汗液挥发到空气中或是渗透到客体中，无色的汗液手印很难用肉眼观察到，因此难以进行直接拍照。利用汗液手印的化学特性，用加氨水催化法配合常用的502胶熏显法，可以较好地显现出手印并加以拍照，为物证鉴定提供依据。     

低温荧光法显现汗潜指纹初探

目的　探索汗潜指纹显现的新方法。方法　利用低温荧光摄影方法加强指纹沉积物的固有荧光强度 ,来提高汗潜指纹显现的成功率。结果　在 4 1 5nm波段激发下用黄滤色镜拍摄指纹的显现效果最好。结论　低温荧光法是一种有效的潜指纹显现的技术手段     

游动配光检验方法的研究

目的研究游动配光检验的方法,利用配光理论指导解决实际问题。方法采用游动配光方法,对痕迹或客体进行“扫描”或游动配光。结果可有效显现非平面光滑客体上较大面积的各种痕迹,并可应用到其它配光技术中。结论丰富和发展了痕迹检验配光理论的内容。     

浅谈对外来人口的指纹建档

指纹档案是情报资料的重要组成部分,已成为侦破各类犯罪案件的有效侦查手段。然而,在外来人口数量猛增,犯罪人数逐年增多,犯罪率居高不下的形势下,只建立违法犯罪人员的指纹档案,已适应不了新形势下的外来人口犯罪的控制和打击,而我国短期内还不能建立全民指纹档案,因此,有必要建立外来人口指纹档案。而且,现代科学技术也为外来人口指纹的采集、建库、识别等各个管理环节,提供了物质、技术方面的保障。     

A Systematic Study to Understand the Effects of Particle Size Distribution of Magnetic Fingerprint Powders on Surfaces with Various Porosities

This study intends to design magnetite (Fe₃O₄)‐based magnetic fingerprint powders with different particle size distributions. It also investigates the influence of particle size distribution on the visualization of latent fingermarks with as little background staining as possible on the surfaces with various porosities in a systematic way. Two strategies were used to prepare the magnetic fingerprint formulations for this study: milling of coarse magnetite particles for different durations, and mixing of sieved fine particles with different size ranges with coarse particles. Particle size analyses of the prepared magnetic powders, optical microscopy‐based roughness analysis of the surfaces and SEM measurements of the visualized fingerprints and representative powders were performed. Mag2 of the formulations prepared through milling and Mag5 and Mag6 of the formulations prepared through sieving and mixing were more successful in the development of latent prints than the rest of the solutions.     

借助三色空间增强图像中指纹反差

如何部分地增强图像反差是刑事技术工作中最常遇到的难题之一。借助数字图像处理技术,可以根据像素值差异从原始图像提取感兴趣部分信息。本文讨论了这种基于像素值差异进行指纹背景分离的方法,可为指纹识别提供便利。