Firearm and toolmark identification criteria: a review of the literature,part II

An update to a previously published review of articles pertaining to firearm and toolmark identification criteria is presented. In this update, 22 additional articles were reviewed, including works of a general nature, studies critically assessing the theory of consecutive matching striations, empirical studies involving various firearm components, toolmark studies, as well as articles discussing the utility of statistics in the firearms and toolmark identification discipline. These articles have been reviewed in a format to permit others to learn what has been published in the field in an effort to educate interested parties. Further, a discussion of the importance of articulation and communication within the discipline is presented.     

A Validation Study of Bullet and Cartridge Case Comparisons Using Samples Representative of Actual Casework

The foundation of firearm and tool mark identification is that no two tools should produce the same microscopic marks on two separate objects that they would be inaccurately or wrongly identified. Studies addressing the validity of identification infrequently employ tests that mirror realistic casework scenarios. This study attempted to do so using a double‐blind process, reducing test‐taking bias. Test kits including bullets and cartridge cases but not the associated firearms were completed by 31 analysts from 22 agencies. Analysis of the results demonstrated an overall error rate of 0.303%, sensitivity of 85.2%, and specificity of 86.8%. Variability in performance across examiners is addressed, and the effect of examiners’ years of experience on identification accuracy is explored. Finally, the article discusses the importance of studies using realistic case work scenarios when validating the field's performance and in providing courts with usable indicators of the accuracy of firearm and tool mark identification.     

Trends in Converted Firearms in England & Wales as Identified by the National Firearms Forensic Intelligence Database (NFFID) Between September 2003 and September 2008

Abstract: The National Firearms Forensic Intelligence Database (NFFID © Crown Copyright 2003‐2008) was developed by The Forensic Science Service (FSS) as an investigative tool for collating and comparing information from items submitted to the FSS to provide intelligence reports for the police and relevant government agencies. The purpose of these intelligence reports was to highlight current firearm and ammunition trends and their distribution within the country. This study reviews all the trends that have been highlighted by NFFID between September 2003 and September 2008. A total of 8887 guns of all types have been submitted to the FSS over the last 5 years, where an average of 21% of annual submissions are converted weapons. The makes, models, and modes of conversion of these weapons are described in detail. The number of trends identified by NFFID shows that this has been a valuable tool in the analysis of firearms‐related crime.     

Homicide-suicide (dyadic death), homicide, and firearms use in England and Wales

Homicide-suicide forms a distinct form of homicide. An analysis of cases in the Yorkshire and Humberside region of England between 1991 and 2005 revealed 37 episodes with 42 victims. Previous studies have shown a high rate of use of firearms. Over the last 2 decades firearms legislation has become more restrictive. In this study all assailants were male, mean age 46.8 years. The commonest method of homicide was strangulation (36%) with 16% killed by firearms. This is a reduction compared with a previous study in the same region. All killers who shot their victims killed themselves with firearms. There were no multiple killings with firearms in this study and no stranger killings. Hanging was the commonest method of suicide. During the same period the use of firearms as a method of homicide increased in England and Wales with handguns, the most common weapon. Nationally, suicide after homicide has remained at a similar rate over the half century and is an uncommon phenomenon. Firearms use remains low in both homicide and homicide-suicide episodes in England, and further analysis is required to determine changes in patterns of killing.     

Development of a 3D-based automated firearms evidence comparison system

Since the early 1990's, the idea of automated systems for the comparison of microscopic firearms evidence has received considerable attention. The main objective of such systems is to enable the analysis of large amounts of evidence, therefore, transforming the comparison of firearms evidence from an evidence verification tool into a crime-fighting tool. Two such systems have been widely used in United States forensic laboratories: namely, the Integrated Ballistics Identification System (IBIS) (1) and DRUGFIRE (2). Both IBIS and DRUGFIRE have in common the fact that their characterization of a specimen is based on a two-dimensional (2D) representation of the specimen's surface. Although these systems have provided satisfactory results in the identification of cartridge cases, their performance in the identification of bullets has not yet met firearms examiner's expectations. This project was motivated by the premise that a better characterizations of the bullet's surface should translate into better performance of automated identification systems. A three-dimensional (3D) characterization of the bullet's surface is proposed as an alternative to a 2D characterization. This paper discusses the development and preliminary results obtained with SciClops, an automated microscopic comparison system based on the use of a 3D characterization of a bullet's surface.     

论表象时代的终结

在科学证言的采信上，法院从有效性的表象或者替代者角度制定了标准，在19世纪和20世纪早期，法院依赖于市场的外行人对专家的行当的普遍接受这一表象。依赖于表象既会使法院犯下假阴性的错误，也会使法院犯下假阳性的错误。在Daubert案中，法院抛弃老旧的Frye普遍接受表象．要求法官要进行认识论探究，以确定所提出的证言是否值得...     

Development and Validation of a Virtual Examination Tool for Firearm Forensics, ,

The transition from 2D imaging to 3D scanning in the discipline of firearms and toolmark analysis is likely to provide examiners an unprecedented view of microscopic surface topography. The digital examination of measured 3D surface topographies has been referred to as virtual microscopy (VM). The approach offers several potential advantages over traditional comparison microscopy. Like any new analytic method, VM must be validated prior to its use in a crime laboratory. This paper describes one of the first validation studies of virtual microscopy. Fifty‐six participants at fifteen laboratories used virtual microscopic tools to complete two proficiency‐style tests for cartridge case identification. All participating trained examiners correctly reported 100% of the identifications (known matches) while reporting no false positives. The VM tools also allowed examiners to annotate compared surfaces. These annotations provide insight into the types of marked utilized in comparative analysis. Overall, the results of the study demonstrate that trained examiners can successfully use virtual microscopy to conduct firearms toolmark examination and support the use of the technology in the crime laboratory.     

A Statistical Validation of the Individuality and Repeatability of Striated Tool Marks: Screwdrivers and Tongue and Groove Pliers*

Abstract: Tool mark identification relies on the premise that microscopic imperfections on a tool’s working surface are sufficiently unique and faithfully transferred to enable a one‐to‐one association between a tool and the tool marks it creates. This paper presents a study undertaken to assess the validity of this premise. As part of this study sets of striated tool marks were created under different conditions and on different media. The topography of these tool marks was acquired and the degree of similarity between them was quantified using well‐defined metrics. An analysis of the resulting matching and nonmatching similarity distributions shows nearly error‐free identification under most conditions. These results provide substantial support for the validity of the premise of tool mark identification. Because the approach taken in this study relies on a quantifiable similarity metric, the results have greater repeatability and objectivity than those obtained using less precise measures of similarity.     

似然比在法庭说话人确认中的应用

本文把成功应用于DNA检验的证据评估方法（似然比）应用于法庭语音证据评估之中,提取语音的LPC作为识别特征,并使用45人电话对话录音中元音/a/作为样本进行了测试。结果表明该方法不仅能正确识别说话人,而且能根据当前嫌疑人样本和问题语音样本的差异,量化该语音样本作为证据的力度,为法庭提供科学合理的证据评估结果和科学解释。同时,自动特征提取的引入比起人工提取共振峰特征,提高了工作效率,识别系统性能也获得大幅提升。     

Three-dimensional surface topography acquisition and analysis for firearm identification

In the last decade, computer-based systems for the comparison of microscopic firearms evidence have been the subject of considerable research work because of their expected capability of supporting the firearms examiner through the automated analysis of large amounts of evidence. The Integrated Ballistics Identification System, which is based on a two-dimensional representation of the specimen surface, has been widely adopted in forensic laboratories worldwide. More recently, some attempts to develop systems based on three-dimensional (3D) representations of the specimen surface have been made, both in the literature and as industrial products, such as BulletTRAX-3D, but fundamental limitations in achieving fully automated identification remain. This work analyzes the advantages and disadvantages of a 3D-based approach by proposing an approach and a prototype system for firearms evidence comparison that is based on the acquisition and analysis of the 3D surface topography of specimens, with particular reference to cartridge cases. The concept of 3D virtual comparison microscope is introduced, whose purpose is not to provide fully automated identification, but to show how the availability of 3D shape information can provide a whole new set of verification means, some of them being described and discussed in this work, specifically, visual enhancement tools and quantitative measurement of shape properties, for supporting, not replacing, the firearm examiner in reaching the final decision.     

Of earprints, fingerprints, scent dogs, cot deaths and cognitive contamination--a brief look at the present state of play in the forensic arena

Over the last decades, the importance of technical and scientific evidence for the criminal justice system has been steadily increasing. Unfortunately, the weight of forensic evidence is not always easy for the trier of fact to assess, as appears from a brief discussion of some recent cases in which the weight of expert evidence was either grossly over- or understated. Also, in recent years, questions surrounding the value of forensic evidence have played a major role in the appeal and revision stages of a number of highly publicized criminal cases in several countries, including the UK and the Netherlands. Some of the present confusion is caused by the different ways in which conclusions are formulated by experts working within the traditional approach to forensic identification, as exemplified by (1) dactyloscopy and (2) the other traditional forensic identification disciplines like handwriting analysis, firearms analysis and fibre analysis, as opposed to those working within the modern scientific approach used in forensic DNA analysis. Though most clearly expressed in the way conclusions are formulated within the diverse fields, these differences essentially reflect the scientific paradigms underlying the various identification disciplines. The types of conclusions typically formulated by practitioners of the traditional identification disciplines are seen to be directly related to the two major principles underpinning traditional identification science, i.e. the uniqueness assumption and the individualization principle. The latter of these is shown to be particularly problematic, especially when carried to its extreme, as embodied in the positivity doctrine, which is almost universally embraced by the dactyloscopy profession and allows categorical identification only. Apart from issues arising out of the interpretation of otherwise valid expert evidence there is growing concern over the validity and reliability of the expert evidence submitted to courts. While in various countries including the USA, Canada and the Netherlands criteria have been introduced which may be used as a form of input or output control on expert evidence, in England and Wales expert evidence is much less likely to be subject to forms of admissibility or reliability testing. Finally, a number of measures are proposed which may go some way to address some of the present concerns over the evaluation of technical and scientific evidence.     

Eyewitness Memory for Firearms: Narrative Accounts and Specific Questioning in the Elucidation of Accurate Information

Much eyewitness research has addressed memory for persons and scenes, but limited work has addressed memory for firearms, frequently an important point in investigations and in court. The present research addressed this topic using the format of a traditional police interview, in which seventy subjects provided unrestricted free recall of a weapon seen in a crime situation, followed by responses to specific questions. Three firearms were used in a between-subjects format: a typical modern semi-automatic pistol, a less-typical Old West revolver, and an atypical single-shot muzzle-loading pistol. In the free recall stage, respondents provided about four times as many correct as incorrect details. However, in the specific-question stage, there were only 1.2 times as many new correct responses as new incorrect details, consistent with current cognitive theory. No difference between the weapons was observed in the production of correct responses, but the revolver and single-shot pistol resulted in more incorrect responses than did the modern semi-automatic, regardless of the saliency of weapon features. These results demonstrate the importance of the original, initial free recall phase in developing accurate identification of a given weapon, and of the type of weapon involved, and have important implications for police interviewing for accurate weapon identification.     

Polygraph admissibility

Polygraph tests are psychological tests that are widely applied in the criminal justice system, but they are rarely administered or studied by psychologists. Two recent federal appeals court decisions may have opened the door to the admissibility of polygraph tests by displacing the long controllingFrye standard. However, these courts have also raised a number of challenges that must be overcome before polygraph tests will be regularly admitted into evidence. We examined the logic of these two recent decisions and the challenges they raise, and we found those challenges to be significant and perhaps daunting. Many of the challenges facing polygraph arise from poor training and a lack of standardization in the polygraph profession. We consider some potential, solutions, but the outlook for change in the polygraph community is dim unless it is forced by the courts or by legislation. Polygraph tests are also challenged by potentially effective countermeasures, and there presently are no easy solutions to those problems. Increased activity and interest are needed from the scientific community if the general situation is to improve.     

A review of the historical use and criticisms of gait analysis evidence

The use of gait analysis is a well-established facet of practice for many professions and a fundamental aspect of clinical practice. In recent times, gait analysis evidence has emerged as a new area of forensic practice. As its use has continued to spread and develop, the area of work has come under close scrutiny and subsequent criticism. The purpose of this paper is to examine the historical use of gait analysis evidence and consider the criticisms of this work. Through the use of the historical records of cases within the public domain it has been determined that gait analysis as evidence was first presented in court over 175?years ago, although it has only been utilized by experts in more recent times. The quality of analysis underpinning such evidence has been variable, and has been undertaken by both non-expert and expert witnesses. The work undertaken by expert witnesses appears to have been both non-scientific and scientific in nature, though there is limited reporting of cases involving scientific approaches. Given the variation in the quality of the methodologies utilized, there is the potential for confusion within the courts, where it may be difficult for the judge or jury to determine the appropriate weight that can be attributed to the evidence. It is concluded that future publications should explore the scientific basis of forensic gait analysis to evaluate standards, reliability and validity, as well as reporting the methodologies utilized in relevant cases in the field. It is also recommended that courts consider in greater depth an expert's theoretical approach and experience prior to admitting their evidence. The publication of ‘Forensic gait analysis: a primer for courts’, although limited in some aspects of its consideration of practice, is a welcome addition to the information available for guidance.     

DNA evidence in South Africa: Lessons learned to date

A trend was noted over the past 15 years in the South African courts. This trend has a multi-factorial origin and highlights the problems faced in the use of forensic science evidence in court. Although there have been improvements on how DNA evidence is gathered and presented in court, due to the fact that certain cases have been contested at the DNA evidence level, multiple issues remain that have not yet been addressed when DNA evidence is submitted to court. These issues include: accreditation, regulation of the forensic science profession, continued education, training of court officials, quality assurance, biased testimony, lack of transparency with regard to processes and procedures followed in the forensic community, incorrect interpretation of DNA evidence, lack of scientific knowledge (including the scientific method) by DNA experts, awareness by the legal profession and an over emphasis on the prosecuting perspective. These same aspects continue to plague current cases. Despite the above, the window of opportunity to address the above has not yet passed. However, it will take continuous and concerted efforts from the scientific and legal professions to bring about the appropriate change to facilitate justice for all in South Africa.     

医学会应做好准备 积极应对专家出席法庭

新修订的《中华人民共和国民事诉讼法》于2013年起开始实施。当事人对鉴定结论有异议,要求鉴定专家出席法庭作证已是大势所趋。医学会开展医疗事故(医疗损害)鉴定,专家签名和出席法庭的问题已经没有讨论的必要,如何采取措施积极应对是医学会要迫切考虑解决的问题。医学会、相关专家学者对这一问题进行过多次讨论,提出了多种建议、过度办法以及应对措施,但具体如何操作,还需要在实践中总结和探索。笔者以为,塑造和培养一支优秀的鉴定专家队伍,保证鉴定结论客观、科学、公正,写好鉴定书分析意见,使鉴定结论令当事人信服,是解决这一问题的关键。     

Objective Evaluation of Subclass Characteristics on Breech Face Marks

Subclass characteristics can be found on the breech face marks left on spent cartridge cases. Even if they are assumed to be rare and their reported number is small, they can potentially lead to false associations. Subclass characteristics have been studied empirically allowing examiners to recognize them and to understand in which conditions they are produced. Until now, however, their influence on the identification process has not been studied from a probabilistic point of view. In this study, we aim at measuring the effect of these features on the strength of association derived from examinations involving subclass characteristics. The study takes advantage of a 3D automatic comparison system allowing the calculation of likelihood ratios (LRs). The similarities between cartridge case specimens fired by thirteen S&W .40S&W Sigma pistols are quantified, and their respective LRs are computed. The results show that the influence of subclass characteristics on the LRs is limited, even when these features are prevalent among the potential sources considered in a case. We show that the proportion of firearms sharing subclass characteristics should be larger than 40% of the pool of potential firearms for the effect to be significant.     

Forensic Facial Comparison: Issues of Admissibility in the Development of Novel Analytical Technique

Much contemporary debate in forensic science concerns validity and admissibility of scientific evidence in court. In this paper, three current approaches to facial identification—image superimposition, photogrammetry, and morphological analysis—are considered with regard to criteria for scientific evidence in the United States, and England, and Wales. The aim of the paper is to assess the extent to which facial image comparison meets criteria of admissibility in these jurisdictions. The method used is a comparative evaluation of the methods of facial image comparison and their underlying premises against the range of admissibility criteria reported in court rulings and relevant judicial and scientific inquiries in the United States and the United Kingdom. While the techniques of facial image comparison are generally accepted within their practitioner communities, they are not tested, and their error rates are unknown. On that basis, the methods of facial image comparison would appear not to meet the anticipated standards. They are, nevertheless, admitted in court in the United States, and England, and Wales. This paper concludes that further research in science and law will be necessary to more definitively establish admissibility of facial image comparison evidence, as it will for other nascent and novel methods that are potentially influential in court proceedings.     

Kumho, Daubert, and the nature of scientific inquiry: implications for forensic anthropology

In the last 15 years, the US Supreme Court has implemented major changes concerning the admittance of expert testimony. In 1993, Daubert v. Merrell Dow Pharmaceuticals superseded the Frye ruling in federal courts and established judges, not the scientific community, as the gatekeepers regarding the credibility of scientific evidence. In 1999, a lesser-known but equally important decision, Kumho Tire v. Carmichael, ruled that technical expert testimony needed to employ the same rigor as outlined in Daubert, but experts can develop theories based on observations and apply such theories to the case before the court. Anthropology has never been defined as a hard science. Yet, many recent publications have modified existing techniques to meet the Daubert criteria, while none have discussed the significance of Kumho to anthropological testimony. This paper examines the impact of Daubert and Kumho on forensic anthropology and illustrates areas of anthropological testimony best admitted under Kumho's guidance.     

植物SSR标记的研究现状及其在法庭科学中的应用

随着SSR分子标记技术的深入研究,其在植物遗传多样性分析、种属鉴定、个体识别中得到越来越广泛的应用。本文就植物SSR分子标记技术的特性、发展、研究现状进行综述,并探讨其在法庭科学中的应用前景,旨在为法庭科学和相关学科中的应用和相关领域中的研究提供参考。