Effect of Aging and Surface Interactions on the Diffusion of Endogenous Compounds in Latent Fingerprints Studied by Mass Spectrometry Imaging,

The ability to determine the age of fingerprints would be immeasurably beneficial in criminal investigations. We explore the possibility of determining the age of fingerprints by analyzing various compounds as they diffuse from the ridges to the valleys of fingerprints using matrix‐assisted laser desorption/ionization mass spectrometry imaging. The diffusion of two classes of endogenous fingerprint compounds, fatty acids and triacylglycerols (TGs), was studied in fresh and aged fingerprints on four surfaces. We expected higher molecular weight TGs would diffuse slower than fatty acids and allow us to determine the age of older fingerprints. However, we found interactions between endogenous compounds and the surface have a much stronger impact on diffusion than molecular weight. For example, diffusion of TGs is faster on hydrophilic plain glass or partially hydrophilic stainless steel surfaces, than on a hydrophobic Rain‐x treated surface. This result further complicates utilizing a diffusion model to age fingerprints.     

Visualization of Aged Fingerprints with an Ultraviolet Laser

Detection of aged fingerprints is difficult because they can degrade over time with exposure to light, moisture, and temperature. In this study, aging fingerprints were visualized by time‐resolved spectroscopy with an ultraviolet‐pulsed laser. Fingerprints were prepared on glass slides and paper and then stored under three lighting conditions and two humidity conditions for up to a year. The fluorescence intensities of the fingerprints decreased with time. Samples were stored in the dark degraded less than in sunlight or under a fluorescent lamp. Samples were stored under low humidity degraded less than under moderate humidity. As the storage period increased, a fluorescence emission peak appeared that was at a longer wavelength than the peak visible in earlier spectra. This peak was used for visualization of an aged fingerprint over time. An image of the fingerprint was not initially visible, but an image appeared as the time since deposition of the fingerprint increased.     

指印印面特征的运用——CNAS-T18指印项目结果解析

通过对CNAS-T18指印项目实施与结果的解析,讨论了当前国内利用指印印面特征的现状：民事案件指印鉴定基础理论的不足。提出了对民事案件指印特征重新进行分类研究,以及探讨、规范利用指印印面特征步骤、方法的必要性和紧迫性。强调了指印印面特征在解决民事案件中的重要作用。     

LED多波段光源显现人民币上潜指印的研究

目的研究显现、提取遗留在人民币上潜在指印的方法。方法采用荧光试剂罗丹明6G对人民币进行染色处理,以LED多波段光源输出的波长为520nm的绿光照射检材,透过580nm的带通型干涉滤光镜观察指印的显现效果,并拍照提取。结果获得亮纹线暗背景的指印图像,指印纹线清晰,反差良好,特征丰富,具备良好的检验鉴定条件。结论 LED多波段光源输出的波长为520nm的绿光与罗丹明6G染色指印的吸收特性吻合,是显现、提取遗留在人民币上潜在指印的良好光源。     

现场遗留手印的分析与判断

随着新刑事诉讼法修改案的实行,法律赋予了犯罪嫌疑人更多人权的同时,给公、检、法机关的工作提出了更高的要求,并就证据的形式,证据的获取途径以及证据链等关于证据的法律效力方面做出了严格的规定和要求。随着社会的发展,各种形形色色的案件层出不穷,而真正留在现场的完整指印将少之又少,如何对现场手印进行分析和判断为侦查提供重要线索,文章结合实践总结出对现场手印分析的工作步骤和方法,以便锁定犯罪嫌疑人成为法庭审判予以采信的重要物证同时也能成为犯罪情报资料的重要来源。手印作为七种证据之一,在今后的打击犯罪和参与刑事诉讼方面仍将发挥重要作用,因此研究手印仍具有实战指导意义。     

Screening for Substance Use Disorders as a Supplement to Caseworker Assessment Among Foster Care–Involved Families

Parental substance abuse is a major factor in families experiencing foster care placement, yet little is known about the potential of screening in determining risk or identifying subpopulations for which elevated risk occurs. One Midwestern state recently implemented screening. This research uses information gathered as part of the screen's implementation to conduct a latent class analysis. The research was extended to provide a detailed examination of differences in child and family characteristics across classes, and to compare the screen results with caseworker impressions. Three distinct typologies emerged, with the high-risk and moderate-risk designations comprising only one quarter of the cases.     

Determining an Optimal Sequence for Chemical Development of Latent Prints on Cartridge Casings and Shotgun Shells*,†

Abstract: In developing latent prints on cartridge casings and shotgun shells, multiple chemical processes should be used in order to obtain the best results. In Phase I, this study established an optimal chemical sequence for both Brass and Nickel cartridge casings based on six sequences involving four chemicals: Cyanoacrylate, Black Powder, Rhodamine 6G and Acidified Hydrogen Peroxide. Phase II was a validation study of Phase I involving a random sample of both Brass and Nickel cartridge casings, which were processed according to the determined optimal sequences. In addition, ribbed shotgun shells were processed under Phase I results and determined to be dependent upon the utilization of a CrimeScope at 515 nm. Consideration should be given to the type of cartridge case being examined. Although limitations exist, some chemical sequences undeniably work better than others. All photographs were manipulated with Adobe^® Photoshop^®. All results were verified by a senior latent print examiner.     

重叠指纹分离方法比较

目的探讨各种重叠指纹分离方法的优劣。方法选取实践中常用方法对重叠指纹进行分离。结果各种方法分离重叠指纹均能达到理想效果,尤其以计算机分离方法适用范围最广、效果最佳。结论计算机重叠指纹分离方法具有较强的现实意义和广阔的应用前景。     

4种粒径的纳米氧化锌粉末显现指印效果的比较

目的比较4种粒径纳米氧化锌粉末显现指印的效果。方法应用上述粉末显现不同类型指印并分别于自然光和紫外光下观察比较显现效果。结果不同粒径粉末显现指印于自然光和紫外光下显现效果和发光颜色不同。结论针对背景颜色和指印类型选用不同粒径粉末。     

mtDNA技术及其在诉讼和事故调查中的应用

本文系统编译整理了线粒体及线粒体 DNA(mtDNA)技术。mtDNA 技术对刑侦、刑事审判与辩护、重大灾害事故调查和民事诉讼以及战争阵亡者母系血统关系认定具有广泛的作用。执法人员、刑事被告人、民事诉讼参与人了解 mtDNA 技术与 DNA 指纹技术的区别才能有效地利用 mtDNA 技术,避免错案和合法权益受到损害。