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。     

Popping the cultural bubble of violence risk assessment tools

Violence risk instruments are administered in medico-legal contexts to estimate an individual’s likelihood of future violence. However, their ostensible limitations; in particular their mono-cultural and risk-centric composition, has drawn academic attention. These concerns may facilitate erroneous risk evaluations for certain non-white populations. Yet it remains unaddressed how cultural differences will be appraised in a risk assessment framework and which specific cultural factors should be considered. Provisions under the Canadian Criminal Code allow for Gladue Reports, to be sought by judicial officers prior to sentencing Indigenous people. Gladue Reports provide insights into an Indigenous person’s unique circumstances that may have led to their offending as well as community-based options for rehabilitation. We proffer that there may be value in augmenting the risk evaluation with culturally relevant Gladue style considerations identified by relevant Indigenous people to provide a more holistic account of an Indigenous individual’s circumstances.     

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.     

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.     

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.     

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。     

The impact of lipid degradation on fingerprint quality on fired firearm cartridges

The recovery of identifiable fingerprints from fired cartridge cases is challenging. Therefore, the characterization of chemical modifications and their effects on fingerprint integrity post-firing is essential. In this study, the primary fingerprint lipids, including myristic acid, pentadecanoic acid, palmitoleic acid, palmitic acid, stearic acid, squalene, and cholesterol in fired and unfired cartridges, were extracted with acetonitrile, followed by derivatization using N,O-Bis(trimethylsilyl)trifluoroacetamide with 1% trimethylchlorosilane (BSTFA/1%TMCS). Squalane was used as the internal standard, and all quantifications were performed using gas chromatography coupled with mass spectrometry using a triple-quadrupole mass filter. All lipids identified in the unfired cartridges were also detected in the fired cartridges, and statistical analysis using Student's t-test and F tests was performed with a 95% confidence level. The concentration of lipids in the unfired cartridges was found to be similar to that detected in the fired cartridges, except for squalene, the recovery of which was 28% lower in the fired cartridges.     

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.     

Informing regional taphonomy research using retrospective forensic anthropology cases in the Western Cape,South Africa

The post-mortem interval (PMI) is important in death investigations as it can assist in reconstructing the context of the case and the identification of the unknown individual. However, in some instances the PMI is challenging to estimate due to the absence of regional taphonomy standards. To conduct accurate and locally relevant forensic taphonomy research, investigators require insight into the regional hotspot recovery areas. Thus, forensic cases examined by the Forensic Anthropology Cape Town (FACT) in the Western Cape (WC) province of South Africa between 2006 and 2018 (n = 172 cases; n = 174 individuals) were retrospectively reviewed. In our study, a considerable number of individuals did not have the PMI estimations (31 %; 54/174) and the ability to estimate a PMI was significantly associated with skeletal completeness, unburnt remains, absence of clothing and the absence of entomological evidence (p < 0.05 for each). Significantly fewer cases had the PMI estimated after FACT was formalised in 2014 (p < 0.0001). One third of cases with PMI estimations were made with large open-ended ranges, making them less informative. Factors significantly associated with these broad PMI ranges were fragmented remains, absence of clothing and absence of entomological evidence (p < 0.05 for each). Most decedents (51 %; 87/174) were discovered in police precincts from high crime areas, yet a considerable number (47 %; 81/174) were also found in low crime and sparsely populated areas regularly used for recreational activities. Common sites of body discovery were vegetated areas (23 %; 40/174), followed by the roadside (15 %; 29/174), aquatic environments (11 %; 20/174) and farms (11 %; 19/174). Decedents were discovered exposed (35 %; 62/174), covered with items such as bedding or shrubs (14 %; 25/174) or buried (10 %; 17/174). Our data highlight gaps in forensic taphonomy studies and clearly informs what regional research is needed. Overall, our study demonstrates how forensic case information can inform regional forensic taphonomy studies to locate common areas and contexts for the discovery of decomposed bodies and encourages similar studies in other areas of the world.     

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.     

Aging studies on fingerprint residues using thin-layer and high performance liquid chromatography

The chemical substances of perspiration found in latent fingerprint residue may hold the key for dating latent fingerprints. To study the chemical transformations of these components as a function of time and environment, fingerprint residues from four males and four females were analysed by thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC). Three major and two or three minor components were detected by both methods and the variation in the quantity of the major components with time was observed.     

Informing the Understudied R: Exploring and Advancing Typological Research

Creating offender typologies has become a growing interest and a potential method of improving understanding of programming needs and potential placements. Most typological research has only explored and described potential offender types. Relatively few studies have attempted to confirm the existence of created typologies or examine how offenders in each type predict important outcomes. Utilizing a large sample (N = 37,111) of reentering male offenders from Washington State Department of Corrections, we computed both an exploratory and confirmatory latent class analysis. After the confirmation of six offender types, we examined each type’s likelihood of several recidivistic outcomes. We anticipate that the described typology will assist case management, prioritizing offender needs, optimizing treatment services, and determining sequencing of multiple treatment types.     

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.