The quantification of fingerprint quality using a relative contrast index

Research into fingermark enhancement techniques has traditionally used visual comparisons and qualitative methods to assess their effectiveness based on the quality of the developed fingermark. However, with increasing research into the optimisation of these techniques the need for a quantitative evaluative method has arisen. Parameters for acceptable fingerprint quality are not well defined and generally encompass clear, sharp edges and high levels of contrast between the fingermark ridges and background material. Using these current parameters, a conclusive measurement of fingerprint quality and thus the effectiveness of development techniques cannot be achieved.This study presents a model through which an aspect of fingerprint quality can be objectively and impartially measured based on a relative contrast index, constructed through measuring the reflective intensity of the fingermark ridges against the background material. Using a fibre-optic spectrophotometer attached to a microscope with axial illumination, the intensity counts of the ridge detail and background material were measured and a logarithmic contrast index constructed. The microscope and spectrophotometer parameters were experimentally tested using a standard colour resolution chart with known reflective properties. The protocol was successfully applied to four sample groups: black inked fingerprints on white paper; latent fingermarks on white paper developed separately with ninhydrin and physical developer; and fingermarks in blood deposited on white tiles and enhanced with amido black. The contrast indices obtained quantitatively reflect the level of contrast and provide an indication of fingerprint quality through a numerical representation rather than previous qualitative methods. It has been suggested that the proposed method of fingerprint quantification may be viable for application in the forensic research arena as it allows the definitive measurement of contrast to aid the evaluation of fingermark detection and enhancement techniques.     

Cognitive and contextual influences in determination of latent fingerprint suitability for identification judgments

We examined forensic fingerprint examiners' suitability determinations of latent fingerprints comparing situations in which the latent is assessed solo (in isolation) versus situations in which it is presented alongside a comparison (matching or non-matching) exemplar print. The presence of a non-matching comparison exemplar led examiners to be more inclined to draw the conclusion that the latent was suitable for comparison compared to when the latent was presented solo. This effect persisted even when the latent presented was highly unsuitable for comparison. The presence of a matching comparison exemplar led examiners to be less likely to decide that the latent was suitable and more likely to decide the latent was questionable compared to solo analysis. This effect persisted even when the latent presented was highly suitable, suggesting a strong main effect. Knowledge of another examiner's previous determination that the latent was unsuitable was found to increase the likelihood that the examiner would conclude that the latent was unsuitable. However, knowledge of a previous “suitable” determination by another examiner did not increase the likelihood of a “suitable” conclusion by examiners. The finding that effects were weaker, although not entirely removed, in those with IAI certification suggests that training may be an appropriate route for reducing the effect of contextual influence and bias in suitability determinations. It was also shown that latent prints that were previously classed as "unsuitable" in a non-biasing context, continued to be judged to be "unsuitable" in a strongly biasing context (a major case in which a previous examiner was purported to have made an Individualization).     

Operational benefits and challenges of the use of fingerprint statistical models: a field study

Research projects aimed at proposing fingerprint statistical models based on the likelihood ratio framework have shown that low quality finger impressions left on crime scenes may have significant evidential value. These impressions are currently either not recovered, considered to be of no value when first analyzed by fingerprint examiners, or lead to inconclusive results when compared to control prints. There are growing concerns within the fingerprint community that recovering and examining these low quality impressions will result in a significant increase of the workload of fingerprint units and ultimately of the number of backlogged cases. This study was designed to measure the number of impressions currently not recovered or not considered for examination, and to assess the usefulness of these impressions in terms of the number of additional detections that would result from their examination.     

电子数据司法鉴定工具可靠性评估研究

探讨建立对电子数据司法鉴定工具进行科学性及可靠性的评估方法。在已有的国内外取证工具评测方法的基础上,借鉴国家强制认证认可和可靠性工程等因素,对电子数据司法鉴定工具可靠性评估体系中的工具基本认可和定性评估二阶段进行详细分析,为保证司法鉴定实践的科学性和准确性提供理论依据。     

应用红外化学成像技术显现潜在的指印

目的应用红外化学（光谱）成像技术显现潜在指纹。方法采用这种新技术进行显现潜在指印的初步实验。结果显示了其对复杂图案背景上指印突出的显现能力。该成像技术具有物质形态特征检验和物质成分检验双重分析能力,在法庭科学领域具有重要的应用价值。     

A metric method for sex determination using the proximal femur and fragmentary hipbone

The pubic bone is considered one of the best sources of information for determining sex using skeletal remains, but can be easily damaged postmortem. This problem has led to the development of nonpelvic methods for cases when the pubic bone is too damaged for analysis. We approached this problem from a different perspective. In this article, we present an approach using new measurements and angles of the proximal femur to recreate the variation in the pubic bone. With a sample from the Terry Collection (n > 300), we use these new variables along with other traditional measurements of the femur and hipbone to develop two logistic regression equations (femur and fragmentary hipbone, and femur only) that are not population specific. Tests on an independent sample (Grant Collection; n = 37-40) with a different pattern of sexual dimorphism resulted in an allocation accuracy of 95-97% with minimal difference by sex.     

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.     

Testing the effectiveness of two cranial base foramina for metric sex assessment of fragmentary remains

Sex differences in linear and area dimensions of the foramen ovale and external opening of the carotid canal were analyzed in a documented French sample (35 men and 32 women). The results demonstrated that a low level of sexual dimorphism is present in the cranial base foramina of this sample, with only two-thirds of the examined variables exhibiting statistically significant differences (p < 0.05) between the sexes. The cross-validated sex classification accuracy rates obtained for univariate and multivariate discriminant functions ranged from only 54.7 to 72.1%. In addition, measurements of the cranial base foramina were found to be difficult to record with precision, with intra-observer error percentages ranging from 2.35 to 4.23%. Error rates of this magnitude may result in the misallocation of specimens. Therefore, osteometric analysis of the foramen ovale and carotid canal external opening cannot be recommended as a useful method for cranial sex assessment in this population group.     

TiO2纳米粉末显现潜在指纹研究

目的建立并比较了TiO2纳米粉末与常规粉末的显现效果。方法使用配粉、色素、疏水性物质对TiO2纳米粉末进行改性，并通过正交实验设计法对综合改性条件进行优化。结果与普通粉末相比，TiO2纳米粉末由于粒度上的优势，具有显现细节特征多、背景表面无粘粉、显现陈旧指纹能力强等优点；通过添加配粉、色素、疏水性物质等改性剂，可以增加TiO2纳米粉末的流散性、扩大粉末与客体背景的反差并提高了其显现潮湿客体的能力。最佳改性方案为使用20％的色素、5：2的配粉比例以及十六胺做疏水性物质。结论TiO2纳米粉末能更有效显现非渗透性客体表面上的潜指纹。     

Proper assessment of the JFK assassination bullet lead evidence from metallurgical and statistical perspectives

The bullet evidence in the JFK assassination investigation was reexamined from metallurgical and statistical standpoints. The questioned specimens are comprised of soft lead, possibly from full-metal-jacketed Mannlicher-Carcano (MC), 6.5-mm ammunition. During lead refining, contaminant elements are removed to specified levels for a desired alloy or composition. Microsegregation of trace and minor elements during lead casting and processing can account for the experimental variabilities measured in various evidentiary and comparison samples by laboratory analysts. Thus, elevated concentrations of antimony and copper at crystallographic grain boundaries, the widely varying sizes of grains in MC bullet lead, and the 5-60 mg bullet samples analyzed for assassination intelligence effectively resulted in operational sampling error for the analyses. This deficiency was not considered in the original data interpretation and resulted in an invalid conclusion in favor of the single-bullet theory of the assassination. Alternate statistical calculations, based on the historic analytical data, incorporating weighted averaging and propagation of experimental uncertainties also considerably weaken support for the single-bullet theory. In effect, this assessment of the material composition of the lead specimens from the assassination concludes that the extant evidence is consistent with any number between two and five rounds fired in Dealey Plaza during the shooting.     

The impact of victim provocation on judgments of legal responsibility: An experimental assessment

This study examines the effects of victim provocation on judgments of the legal responsibility for a homicide. Previous research and various legal rulings suggest that victim provocation is related to judicial decision-making. However, the magnitude of this relationship has not been assessed.Using a quasi-experimental procedure in which subjects read a case account of a homicide, this study indicates that as victim provocation increases, the level of legal responsibility and the years of imprisonment attributed to the offender decreases. The paper concludes with suggestions for future research in actual judicial decision-making, victim precipitation, and applying an attributional framework to these areas.     

Informing the Population About the Activity of State Agencies

Under the conditions of developed socialism, the general problem of informing the population, and that of its knowledge about matters of state and law in particular, becomes increasingly more pertinent. "The development of socialist democracy," said L. I. Brezhnev at a meeting with voters of the Bauman Electoral District in Moscow on June 10, 1966, "demands the solution of many problems that the Party has placed on the order of business." One of these tasks is "providing fuller information to the people about everything happening within the country and on the world scene, and increasing publicity [glasnost'] about the work of the agencies of Soviet government." The Communist Party associates improvement of socialist democracy particularly with the level of society's information "about the policies of the Party and state." (1) Therefore, the Soviet government pays much attention to the solution of questions associated with informing the citizenry about the work of governmental agencies and also about their regulation by law. Thus, for example, in the RSFSR law "On the District Soviet of Working People's Deputies of the RSFSR" (June 29, 1971), we read about the responsibility of the executive committee to inform the population about questions placed on the order of business of the soviet (Article 33), to bring decisions of the district soviet to the knowledge of the citizens (Article 38), and to report on its work at meetings of the working population and at citizens' places of employment (Article 55). Article 93 reads: "The district soviet of working people's deputies is responsible for informing the population about its functioning. …" Presidiums of the supreme Soviets of union and autonomous republics monitor observation of provisions of the law, assuring that the population will be widely informed on the work of state agencies. (2) In this connection, examination of the question of the content and forms whereby the population of the USSR becomes informed about the activity of state agencies is of interest.     

微晶荧光乳浊液显现血、汗指纹的研究

目的　显现非渗透性和半渗透性客体上的血指纹、汗潜指纹。方法　应用微晶小颗粒荧光乳浊液显现血、汗指纹。结果　对常见的各种非渗透性和半渗透性客体上的新鲜和陈旧的血、汗指纹均可显出。结论　该方法与传统的物理显现方法相比较在于显出效果基本不受指纹遗留时间和客体的性质及表面颜色的影响 ,并且此方法实用、可靠 ,同时该配方还可用于非渗透性和半渗透性客体上涉油指纹的显现 ,是常见客体上血、汗指纹显现的一个重要突破     

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     

偏振光照相显现镜面客体上的潜在指印

目的研究镜面客体上潜在指印的偏振光照相显现方法。方法用偏振光照相分别对普通镜面和CD盘上的油脂指纹、灰尘指印进行显现。结果显现指纹清晰,通过与定向反射、暗视场照相方法进行比较,偏振光照相效果明显好于其他光学方法。结论偏振光照相可以有效地增加指印纹线与背景的亮度反差,消除物体背景干扰。     

Optical enhancement of fingerprint deposits on brass using digital color mapping

Abstract: The reflection of visible light from α‐phase brass subject to surface oxidation in air at elevated temperatures is investigated. X‐ray photoelectron and auger electron spectroscopy confirm that covered areas of brass (not exposed to air) display dezincification but an absence of significant surface oxidation, confirming a differential oxidation mechanism. Visualization of differential oxidation is shown to be enhanced by selective digital mapping of colors reflected from the surface of the brass using Adobe^® Photoshop^®. Enhancement is optimal when the brass is heated to ～250°C with areas of oxidation having a mirror‐like appearance. The use of this enhancement method to produce a faithful image of fingerprint ridge characteristics is demonstrated on brass shell casings where fingerprints were deposited prefiring.     

彩色背景客体上手印的显现方法

目的利用真空金属镀膜法和＂502＂胶熏显法之间的空间互补性原理,考察显现杂色背景客体表面潜手印过程中遇到的杂色背景干扰问题。方法对杂色背景客体表面的同一枚手印分别采用紫外照相、＂502＂胶熏显、真空镀膜方法处理,比较去除背景干扰能力。结果采用＂502＂胶熏显,真空金属镀膜后期增强处理,能够使指纹纹线清晰连贯,并能有效消除背景杂色干扰。结论该方法可有效消除背景杂色干扰,清晰显现有彩色背景的易拉罐、照片纸等客体上的指纹。     

Forensic applications of chemical imaging: latent fingerprint detection using visible absorption and luminescence

Chemical imaging technology is a rapid examination technique that combines molecular spectroscopy and digital imaging, providing information on morphology, composition, structure, and concentration of a material. Among many other applications, chemical imaging offers an array of novel analytical testing methods, which limits sample preparation and provides high-quality imaging data essential in the detection of latent fingerprints. Luminescence chemical imaging and visible absorbance chemical imaging have been successfully applied to ninhydrin, DFO, cyanoacrylate, and luminescent dye-treated latent fingerprints, demonstrating the potential of this technology to aid forensic investigations. In addition, visible absorption chemical imaging has been applied successfully to visualize untreated latent fingerprints.     

利用光学滤波方法提取透明薄片上的指纹

目的将透明薄片材料上的指纹看作＂位相物＂,利用阿贝-波特空间滤波实验进行显现研究;方法通过光学4f系统利用暗场法进行空间滤波,并将实验结果和刑事照相中的透射配光方法进行比较。结果该种方法透明薄片材料上微弱汗液指纹的显现取得较好的效果;结论利用阿贝-波特空间滤波实验可以显现部分透明薄片材料上的指纹,有关细节问题有待进一步研究。