Cognitive issues in fingerprint analysis: inter- and intra-expert consistency and the effect of a 'target' comparison

Deciding whether two fingerprint marks originate from the same source requires examination and comparison of their features. Many cognitive factors play a major role in such information processing. In this paper we examined the consistency (both between- and within-experts) in the analysis of latent marks, and whether the presence of a 'target' comparison print affects this analysis. Our findings showed that the context of a comparison print affected analysis of the latent mark, possibly influencing allocation of attention, visual search, and threshold for determining a 'signal'. We also found that even without the context of the comparison print there was still a lack of consistency in analysing latent marks. Not only was this reflected by inconsistency between different experts, but the same experts at different times were inconsistent with their own analysis. However, the characterization of these inconsistencies depends on the standard and definition of what constitutes inconsistent. Furthermore, these effects were not uniform; the lack of consistency varied across fingerprints and experts. We propose solutions to mediate variability in the analysis of friction ridge skin.     

Toward multidimensional information: A derivatization-free UHPLC-QqQ MS/MS method for amino acid components of fingerprint

The analysis of fingerprint chemical composition is a meaningful way to excavate the multidimensional information of fingerprint, including the donor profiling information and the age of a fingerprint, which broadens the evidential values of fingerprint, especially for the partial and distorted fingerprint. But the research remains still in the pilot phases or is ongoing. Amino acids are the dominant organic substances in latent sweat fingerprint and influenced by many donor factors. Hence, their content reflects personal information of donors. Forensic science will be revolutionized if suspects can be individualized by their amino acid content. The diverse nature, distinct physicochemical properties, and ultra-micro levels of amino acids present in fingerprints make it hard to detect. A high sensitivity method for detecting and quantifying multiple amino acid components is required. UHPLC-QqQ MS/MS offers high sensitivity, high separation, simultaneous multicomponents detection, and no derivatization, making it an ideal method for detecting and analyzing amino acids in fingerprints. Therefore, in this study, we propose and validate an efficient UHPLC-QqQ MS/MS method for the extraction and analysis of 13 amino acids from fingerprint. We compared the results of amino acids of 10 different substrates and found that the inherent amino acids in most porous substrates would have been extracted along with the fingerprint amino acids, making them unsuitable for quantitative amino acid analysis. Instead, plastic sheets are ideal substrates for laboratory studies. Then, extensive experiments were conducted among 30 donors for multidimensional information analysis. The type of samples analyzed were eccrine-rich fingerprints. A Binary Logistic Regression (BLR) model was developed, and the female and male donors were successfully differentiated by amino acids in fingerprints. Two other mathematical models were also developed to verify the accuracy, and all three different mathematical models were able to identify donors of different genders with over 90% accuracy. This demonstrates that amino acids have the potential to provide more information for donors as metabolic markers. In the future, we will conduct a series of experiments to analyze more multidimensional information for individual identification by amino acid content in the fingerprint.     

战术心理战在警察实施清查行动中的作用

公安机关实施清查行动是针对犯罪分子或重大犯罪嫌疑人可能藏身落脚或来往出没的地点、场所进行清理和检查的一类作战行动。警察通过清查行动其目的在于寻找、发现和缉捕违法、犯罪分子或犯罪嫌疑人。心理战是攻心战。警察心理战,是通过各种有效的途径、渠道,运用不同的方式、方法及手段,为了治理、防控、打击、制服社会违法犯罪,而积极地影响、作用或利用执法对象心理状态、品格及其心理弱点的活动过程。而清查行动中实施战术心理战,则是警察为了在执行清理和检查任务时,为达到战术目的而进行的心理攻势,这是一种对抗状态下的战术心理战运用。通过清查行动中战术心理战的应用,尽快识别作战对象,从而达到清查行动的战术组织实施目的,提高清理检查行动的适应性和效率效益。     

对尸体指纹种类认定依据的研究

指纹状态属性的认定是当前指纹鉴定工作的一个新课题。指纹鉴定中的押名指印一般情况下都是押名人生前主动捺印形成的,但在实践中有时会出现作案人为了扰乱侦查视线、逃避惩罚或获取某种利益,而利用尸体指纹捺印伪造死者生前的押名指印的情况,因此对尸体指纹种类认定的研究将有助于侦查破案或对事实的确认。早期尸体现象是尸体指纹具备区别于活体指纹的特定性和相对稳定性的关键,再加上指纹本身所具有的反映性,这＂三性＂共同构成了尸体指纹种类认定的科学基础,为判定尸体指纹提供了理论依据。对于尸体指纹的研究,一方面须得益于尸体指纹捺印外观特征规律的深入总结,而另一方面也需要将微观层面的尸体指纹汗孔特征作为研究的切入点。总之,研究的最终目的就是提高尸体指纹种类认定的科学可靠性,进而使这一认定结论能作为一种科学的鉴定意见在诉讼中运用。     

Photographic Image Comparison of Vegetation

Images and videos are common types of evidence in crime scene investigations and laboratory analysis. Images may be taken by the suspect and/or by crime scene investigators and may serve as crucial elements in forensic laboratory analysis. Forensic photographic image comparison is the process of comparing one or more objects or persons in photographs/images when at least one image is known to be related to a crime. The forensic examiner usually compares the images in order to determine whether or not an association between the exhibits in the images can be made. This paper proposes an extension to the currently prevalent photographic image examination method. The extension introduces comparison of landscape and vegetation over time. It is revealed that similarities between images may still be found between the period of time the suspect photograph was taken and the period the crime scene investigator took the photograph from the same area. In this case report, two suspects to be involved in growing a marijuana field were arrested by the police. The forensic experts were asked to examine images taken by the crime scene investigators and to compare them to the images found in the suspects’ phones. They then tried to determine whether the suspects could be linked to the specific locations. While applying techniques derived from morphological comparison methodologies, the plants at the scene provided significant additional information. A tree trunk, branches, and twigs on a hedge in the photographs revealed specific individual characteristics that led the examiner to reach a conclusive decision.     

The skin as a repository and masker of evidence

The role of the skin as a repository and masker of evidence is evaluated. Skin examination and testing are very important in the (a) identification of victims and suspects (for example, by fingerprints, lip prints, and fingernail marks), (b) recognition of patterns and shape of injurious energy impacts (for instance, recognition of type of injury and particular weapon), and (c) recovery of embedded evidence (for example, glass, wood, powder, explosives, and paint). It is also important to realize that the skin may conceal evidence by masking significant and/or lethal internal injuries.     

Chemical composition of fingerprints for gender determination

This work investigates the chemical nature of fingerprints to ascertain whether differences in chemical composition or the existence of chemical markers can be used to determine personal traits, such as age, gender, and personal habits. This type of information could be useful for reducing the pool of potential suspects in criminal investigations when latent fingerprints are unsuitable for comparison by traditional methods. Fingertip residue that has been deposited onto a bead was extracted with a solvent such as chloroform. Samples were analyzed by gas chromatography/mass spectrometry (GC/MS). The chemical components identified include fatty acids, long chain fatty acid esters, cholesterol and squalene. The area ratios of ten selected components relative to squalene were calculated for a small preliminary experiment that showed a slight gender difference for three of these components. However, when the experiment was repeated with a larger, statistically designed experiment no significant differences between genders were detected for any of the component ratios. The multivariate Hotelling's T2 test that tested all ten-component ratios simultaneously also showed no gender differences at the 5% significance level.     

Ridge Width Correlations between Inked Prints and Powdered Latent Fingerprints

A methodology to estimate the time of latent fingerprint deposition would be of great value to law enforcement and courts. It has been observed that ridge topography changes as latent prints age, including the widths of ridges that could be measured as a function of time. Crime suspects are commonly identified using fingerprint databases that contain reference inked tenprints (flat and rolled impressions). These can be of interest in aging studies as they provide baseline information relating to the original (nonaged) ridges’ widths. In practice, the age of latent fingerprints could be estimated following a comparison process between the evidentiary aged print and the corresponding reference inked print. The present article explores possible correlations between inked and fresh latent fingerprints deposited on different substrates and visualized with TiO₂. The results indicate that the ridge width of flat inked prints is most similar to fresh latent fingerprints_, and these should be used as the comparison standard for future aging studies.     

Forensic Evidence and Criminal Investigations: The Impact of Ballistics Information on the Investigation of Violent Crime in Nine Cities,

We explore the impact of information from ballistics imaging hit reports on the investigation into violent crimes. Ballistics imaging hits link two crimes involving the same firearm by forensically matching tool marks on the fired bullets or cartridge cases. Interview data collected from detectives who received a hit report were used to explore the relationship between the presence of a hit report and outcomes in 65 gun‐related violent crime investigations in nine U.S. police agencies. Findings indicate hit reports rarely contribute to identification, arrest, charging, or sentencing of suspects, because of delays in producing hit reports. On average, hit reports were completed 181.4 days after the focal crime. This delay forces investigations to proceed without the benefit of information from ballistics analysis. Additionally, hit reports rarely contained detailed information that was immediately useful to investigators. Instead, hit reports required additional research by the investigator to unlock useful information.     

The Impact of Beliefs Concerning Deception on Perceptions of Nonverbal Behavior: Implications for Neuro-Linguistic Programming-Based Lie Detection

Regularly employed in a forensic context, the Neuro-Linguistic Programming (NLP) model purports that the behavioral distinction between somebody who is remembering information and somebody who is constructing information lies in the direction of their eye movements. This strategy reflects numerous current approaches to lie detection, which presume that nonverbal behavior influences perceptions and judgments about deception. The present study emphasized a reverse order by investigating whether beliefs that an individual is deceptive influence perceptions of the respective individual’s nonverbal behavior as indicated by observed eye movement patterns. Sixty participants were randomly assigned to either a group informed that right eye movements indicate constructed and thus deceptive information or a group informed that left eye movements indicate constructed and thus deceptive information. Each participant viewed six investigative interviews depicting the eye movement patterns of mock suspects labeled as deceptive or truthful. The interviews were structured according to different right/left eye movement ratios. Results revealed that participants reportedly observed the deceptive suspects displaying significantly more eye movements in the direction allegedly indicative of deception than did the truthful suspects. This result occurred despite the fact that the actual eye movement ratios in both deceptive/truthful sets of interviews were identical and the eye movements were predominantly in the opposite direction of that allegedly indicative of deception. The results are discussed in the context of encoding-based cognitive-processing theories. Limitations on the generality of the results are emphasized and the applicability (or lack thereof) of NLP-based lie detection in forensic contexts is discussed.     

Meta-analytically quantifying the reliability and biasability of forensic experts

Abstract:  In this paper we employ meta-analytic procedures and estimate effect sizes indexing the degree of reliability and biasability of forensic experts. The data are based on within-expert comparisons, whereby the same expert unknowingly makes judgments on the same data at different times. This allows us to take robust measurements and conduct analyses that compare variances within the same experts, and thus to carefully quantify the degree of consistency and objectivity that underlie expert performance and decision making. To achieve consistency, experts must be reliable, at least in the very basic sense that an expert makes the same decision when the same data are presented in the same circumstances, and thus be consistent with themselves. To achieve objectivity, experts must focus only on the data and ignore irrelevant information, and thus be unbiasable by extraneous context. The analyses show that experts are not totally reliable nor are they unbiasable. These findings are based on fingerprint experts decision making, but because this domain is so well established, they apply equally well (if not more) to all other less established forensic domains.     

Eyewitness identification procedures for multiple perpetrator crimes: a survey of police in Sweden,Belgium, and the Netherlands

ABSTRACT

A considerable proportion of crimes involve multiple perpetrators. Yet, little is known about how police officers construct, administer, and record eyewitness identification procedures for multiple suspects. An online survey of law enforcement agents in Sweden, Belgium, and the Netherlands (N?=?51) was conducted to obtain an initial understanding of police perceptions of prevalence and characteristics of multiple perpetrator crimes, and to examine identification procedure practices given the little to no guidance provided for police. Practice converged when it came to the use of sequential, photographic lineups, but diverged between and within countries on whether or not suspects of multiple perpetrator crimes should be placed in separate lineups. Results specifically highlight contextual cuing as one critical area for future research in identification for multiple perpetrator crimes (i.e. placing multiple suspects in the same lineup or asking eyewitnesses to look for a specific suspect).     

Detection and Identification of Explosive Particles in Fingerprints Using Attenuated Total Reflection-Fourier Transform Infrared Spectromicroscopy

Abstract:  The application of attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectromicroscopy for detection of explosive particles in fingerprints is described. The combined functions of ATR-FTIR spectromicroscopy are visual searching of particles in fingerprints and measuring the FTIR spectra of the particles. These functions make it possible to directly identify whether a suspect has handled explosives from the fingerprints alone. Particles in explosive contaminated fingerprints are either ingredients of the explosives, finger residues, or other foreign materials. These cannot normally be discriminated by their morphology alone. ATR-FTIR spectra can provide both particle morphology and composition. Fingerprints analyzed by ATR-FTIR can be used for further analysis and identification because of its non-destructive character. Fingerprints contaminated with three different types of explosives, or potential explosives, have been analyzed herein. An infrared spectral library was searched in order to identify the explosive residues. The acquired spectra are compared to those of finger residue alone, in order to differentiate such residue from explosive residue.     

Recent Supreme Court of Canada rulings on criminal defendants' right to counsel

The Supreme Court of Canada recently issued a trilogy of decisions pertaining to suspects' right to legal representation. These rulings further a major difference between the US and Canadian law: Canadian criminal suspects have far less access to legal counsel than suspects in the USA. This paper summarizes these decisions and draws comparisons between Canadian and the US criminal procedure with respect to a suspect's rights to legal representation. We present preliminary data on Canadian citizens' misunderstanding of criminal suspects' right to counsel and also Canadian legal professionals' opinions about the right to counsel. We recommend empirical investigation of the hypothesis that Canadian suspects are more likely than the US suspects to make false confessions.     

文件上有色指印非纹线特征的应用研究

为了充分地发掘模糊指印形态特征在司法实践中的可用性和实用性,我们利用文件上有色指印的阶段性痕迹--墨迹边缘状态、积墨形态分布“、空白”形态分布及其相互位置关系等非纹线特征,分析研究了不同捺印人以油墨为介质连续捺印的样本指印50组共200枚,结果发现使用非纹线特征能够准确地分辨出同一手指连续捺印的同组指印。本文还对应用指印非纹线特征的各项技术要点进行了讨论,并且列举了该方法用于鉴定实践的三个成功案例。指印非纹线特征的应用不仅改变了对模糊指印只能出“具不具备鉴定条件”的结论模式,而且使适合使用该方法的被检指印形成相对时间的难题得到解决。     

犯罪现场勘查存在的问题及其对策

通过现场勘查,就是要查清事件的性质,即研究和了解犯罪分子作案情况、作案动机和手段;研究和了解犯罪分子本人的特点和特征;发现和提取犯罪分子作案遗留的痕迹、物证;为侦查破案提供各方面的犯罪信息。侦查人员依靠这些犯罪信息,“再现犯罪”,确定侦查范围,制定侦查计划,采取侦查措施,进行侦查破案。     

单核苷酸多态性与外在可见特征的关联及法医学意义

人群中有很多由基因导致的生理变异,可用于个人识别标志及身份证明。作为第三代遗传标记,单核苷酸多态性（SNP）已被证明与人体的许多表型差异有关。法医学可以利用SNP这个特性,通过检验SNP位点,预测犯罪者的外在可见特征（EVCs）,缩小犯罪嫌疑人范围。     

多源图像融合技术及其在公安刑事摄影工作中的应用

近年来,多源图像融合技术的应用越来越多,它可以将同一场景以不同成像方式或者不同成像时间获得的不同图像融合为一幅图像。这种技术可以综合多张照片的信息量,提高视觉感知,便于进行计算机的处理,因此,可在公安刑事摄影工作中用于对疑难指纹、立体痕迹、强反光客体痕迹、高逆光现场照片等的拍摄和处理,从而最大程度的准确反映被摄景物的实际情况。     

论我国医疗损害技术鉴定制度构建

《侵权责任法》仍未解决我国医疗鉴定体制的二元化问题。医学会医疗事故技术鉴定和法医医疗损害司法鉴定两种模式各有利弊,法医鉴定模式并不比医学会鉴定模式优越。在专业技术问题的判断上,日本、德国、荷兰、美国的医疗损害鉴定模式都采同行评价的原则。构建我国医疗损害技术鉴定制度应坚持充分利用现有鉴定资源、尽可能融合当前两种鉴定的优点、法律问题与技术问题分离的宏观理念,并坚持公开、救济、辩论、鉴定专家半职业化、鉴定方法科学和法律指导的基本原则。在制度的具体构建上,鉴定名称应选择医疗损害鉴定或医疗损害技术鉴定;新的鉴定机构应在现有医学会医疗事故技术鉴定机构的基础上组建,并要求法医专家参与。调整鉴定专家来源、专家鉴定组和鉴定专家库组成,完善鉴定程序,确定鉴定理论、鉴定方法．明确鉴定原则,扩充医疗：愤害技术鉴定的内容;也可以借鉴日本的鉴定模式,由医学会建立专家库,由法院启动、组织鉴定。