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.     

Sexual and violent recidivism by offender type and actuarial risk: reoffending rates for rapists,child molesters and mixed-victim offenders

Abstract

The current study examines sexual and violent reoffence rates for a sample of 2474 sexual offenders over an average of 15 years following release from prison. Reoffence rates are reported as a function of the offenders' victim type and level of risk as assessed by the Automated Sexual Recidivism Scale, a computer scored measure of relevant historical risk factors. Observed sexual recidivism rates for offenders with child victims, adult victims, and mixed victims were quite similar. Results indicate that offenders with exclusively female child victims not only showed a lower rate of sexual reoffending, but that the reoffence rates were relatively low across all levels of actuarial risk. In contrast, those with male child victims and adult victims showed a pronounced escalation of reoffence rates as actuarial risk increased. Results also indicated that adult victim offenders are less consistent in the victim type of their reoffences, with 37% sexually reoffending against child victims. Finally, combined rates of sexual and violent reoffending were particularly high for those with adult victim sexual offence histories. Risk assessment and public policy implications are discussed.     

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。     

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.     

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。     

Déjà vu All Over Again: Investigating Temporal Continuity of Adolescent Victimization

An important theoretical issue in the study of criminal victimization focuses on state dependence or the extent to which prior victimization causally affects subsequent victimization. Framing this issue are two conceptual arguments that posit divergent predictions regarding the impact of past victimization. While “victim labeling” suggests that the experience of prior victimization increases victimization in the future, “victim rationality” suggests that past victimization decreases subsequent victimization. To date there has been little longitudinal research that explicitly evaluates these competing viewpoints. In response, the current study uses panel data from a sample of adolescents to assess the merit of these opposing theoretical frameworks. Against this theoretical backdrop, it is shown that prevailing strategies for the analysis of panel data—random-effects and fixed-effects—produce erroneous results that add confusion to the debate regarding the nature of state dependence processes in criminal victimization. Drawing from advances in econometrics, two estimators that can overcome the problems that plague more traditional panel data models are used to provide a test of the competing victimization perspectives. Results from those analyses suggest support for the thesis that past victimization increases subsequent victimization, but the magnitude of this positive relationship is more modest than is indicated by analytic models that have been utilized in prior longitudinal victimization research.

Using State Child Labor Laws to Identify the Causal Effect of Youth Employment on Deviant Behavior and Academic Achievement

On the basis of prior research findings that employed youth, and especially intensively employed youth, have higher rates of delinquent behavior and lower academic achievement, scholars have called for limits on the maximum number of hours per week that teenagers are allowed to work. We use the National Longitudinal Survey of Youth 1997 to assess the claim that employment and work hours are causally related to adolescent problem behavior. We utilize a change model with age-graded child labor laws governing the number of hours per week allowed during the school year as instrumental variables. We find that these work laws lead to additional number of hours worked by youth, which then lead to increased high school dropout but decreased delinquency. Although counterintuitive, this result is consistent with existing evidence about the effect of employment on crime for adults and the impact of dropout on youth crime.

半导体纳米材料显现潜在手印技术的研究新进展

自纳米技术引入到法庭科学领域以来,因其独特的优势,拓宽了手印技术工作人员的思路,受到了国内外法庭科学家的青睐,成为当前国内外手印学科学家研究的热点。本文主要介绍了半导体纳米材料显现手印的概念特点,并就半导体纳米材料显现手印技术的发展历程和最新进展作了较为详细的归纳和总结。     

粘有纸张的胶带剥离同时显现胶黏面指纹

为了更好地解决粘贴在普通A4纸上的胶带剥离与胶粘面指纹同时显现问题,本文对不同剥离试剂的剥离效果、不同显现试剂的显现效果以及不同胶粘面汗潜指纹遗留时间的影响进行了比较。实验结果表明,丙酮与无水乙醇按照1:10混合而成的试剂剥离效果最好;聚乙二醇和上海牌214型碳素墨水按照1:15混合而成的试剂显现效果最好;遗留5-7天的胶粘面汗潜指纹经染色2次后显现效果最佳,10-20天的实验样本经染色3次后显现效果最佳。