Context matters: Alibi strength varies according to evaluator perspective

Purpose . The nascent field of alibi evaluation research has produced interesting and inconsistent findings. We focus on a heretofore unexamined variable that may play a critical role in alibi evaluation: context. Specifically, two experiments tested the hypothesis that the same alibi can be evaluated differently when presented in the context of a police investigation vs. criminal trial. Method . In Study 1, 101 college participants evaluated an alibi in one of three contexts: police investigation, criminal trial, or a control condition devoid of specific legal context. Dependent measures included ratings of alibi strength and credibility, as well as the likelihood that the suspect was guilty. In Study 2, both context and the presence of a corroborating witness were varied in a scenario presented to 139 college participants. Results . Across studies, an alibi was rated as stronger in the police investigation vs. trial context, consistent with the prediction that the fact that a case has proceeded to trial implies to perceivers that the alibi is relatively weak. In Study 2, an alibi was deemed stronger when corroborated vs. uncorroborated, but this difference was only significant in the police investigation context. Conclusions . If alibi research is to fulfil its promise for legal and policy implications, a clearer understanding of the variables that influence alibi evaluation must be developed. The present results illustrate the importance of context in this investigation, suggesting that two researchers studying evaluations of the same alibi may arrive at different conclusions based on the simple framing of the experimental task.     

Logical evaluation of evidence when a person is suspected of committing two separate offences.

We consider the problem of drawing inferences within a legal framework when a person is a suspect for two separate offences. Although we are primarily concerned with scientific evidence the issue inevitably arises as to how that evidence interacts with other, non-scientific evidence. We show that, in this particular context, the evidence can be conveniently classified into three categories that concern, respectively: the first crime only; the second crime only; and evidence that relates to similarities between the two crimes. Two case examples are considered and we consider DNA, fibres and eyewitness evidence. These are viewed from the perspective of a prosecutor who has to decide whether or not to charge a suspect with one or both crimes. Graphical sensivity analyses are presented which have features that are not intuitively obvious.     

Calculating likelihood ratios for a mixed DNA profile when a contribution from a genetic relative of a suspect is proposed

This technical note describes a practical method for evaluating evidence in the case of a two person conditioned DNA mixture where the defence proposition is that the unknown contributor is genetically related to the suspect. A conditioned mixture is one where the presence of DNA from one of two individuals is accepted by both prosecution and defence. A typical example would be a vaginal swab in an alleged rape case, where the presence of the complainant's DNA would be expected and samples have been taken from the complainant and a suspect. Much has been written about the interpretation of such mixtures and the calculation of the conditional genotype probabilities that must be carried out. In general, such treatments assume that the unknown contributor, under the defence proposition, is unrelated to the known individuals. In this paper, we consider the case where the defence proposition is that the unknown contributor is genetically related to the suspect. We describe a method, incorporating a flow chart and reference tables that facilitate manual calculations of the likelihood ratio for several postulated genetic relationships.     

Quantitative assessment of evidential weight for a fingerprint comparison I. Generalisation to the comparison of a mark with set of ten prints from a suspect

The authors have published elsewhere a quantitative method for assessing weight of evidence in the case where a finger mark from a crime scene is compared with a control print taken from a single finger of a suspect. The approach is based on the notion of calculating a likelihood ratio (LR) that addresses a pair of propositions relating to the single finger that was the origin of the crime mark. In practice, things are rather different because the crime mark will not just be compared with a single finger from a suspect but with a set of prints from all of his/her fingers; likewise, when the mark is compared with a database, this will consist of ten print records from random individuals. It is clear that "finger propositions" are not realistic in this situation and we show how our approach may be generalised to address a pair of propositions that relate to the person that made the crime mark. It often is the case that information is present at the crime scene that enables some inference to be drawn relating to which of the offender's ten fingers left a particular mark of interest. This kind of inference may profitably be drawn into the formal analysis. We illustrate our approach with an example.     

认罪案件办理机制研究

认罪是犯罪嫌疑人、被告人的一项权利,是他们对所指控之罪的承认。它可发生在侦查阶段、审查起诉阶段或审判阶段。从程序法意义上看,认罪是一种法律行为,可引起某种特定刑事诉讼程序的发生、改变或终结;从实体法意义上看,认罪可导致犯罪嫌疑人、被告人刑罚被减轻或免除。我国认罪案件办理机制存在的主要问题是：该机制的独立价值未得到充分彰显;司法实务部门对该机制的探索性实践有违法之嫌;程序设计具有一定的不合理性,影响了该机制充分发挥其功能;相关配套制度不健全,难以保证认罪的自愿性。对我国认罪案件办理机制的完善,应从确认机制、快速办理机制、激励机制和弹劾机制等4个方面进行体系性的思考和安排。     

Trace DNA: a review,discussion of theory,and application of the transfer of trace quantities of DNA through skin contact

Advances in STR PCR DNA profiling technology allow for the analysis of minute quantities of DNA. It is frequently possible to obtain successful DNA results from cellular material transferred from the skin of an individual who has simply touched an object. Handling objects, such as weapons or other items associated with a crime, touching surfaces, or wearing clothing, may represent sufficient contact to transfer small numbers of DNA bearing cells, or trace DNA, which can be successfully analyzed. With this minimal amount of contact required to yield a suspect profile comes tremendous crime solving potential, and a number of considerations for prudent application, and the maximization of evidentiary value. Evidentiary materials not previously considered must be recognized and preserved, and the resulting DNA type profiles interpreted in their proper forensic context.     

The combined use of pollen and soil analyses in a search and subsequent murder investigation

This case report shows how soil analyses (particularly petrology) can be used in conjunction with pollen in order to refine or strengthen an association. Soil samples from a car believed to have been used by the suspect in a missing persons case was subjected to soil and pollen analyses. The soil characteristics and petrology were used to redefine the search area using geology and soils maps, the pollen and vegetative remains were used to target woodlands with a particular species mix. As a result two bodies were located and the environmental evidence was used in the subsequent trial. In this case the history of the vehicle was well known and the wheel arches and footwells provided reliable soil traps. The advantage of combining the techniques is that soil evidence (both mineralogy and other inclusions) provides a geological/soils match while the pollen provides independent evidence of vegetation type providing a combination that may be rare or unique.     

When is a capitally charged defendant incompetent to stand trial?

Competence to stand trial is a functional test rather than a bright line test, which therefore requires a case and fact specific assessment of a client's abilities in context. This article discusses competence in the context of capital trial cases. There are serious potential pitfalls for the client when raising incompetence and the decision to do so must be based on the specific ways in which the client's mental illness interferes with specific abilities to communicate with counsel and understand the proceedings. This article addresses counsel's duties in the context of assessing competence, but focuses on the little addressed issue of what abilities a client must have and what tasks a client must participate in so as to be engaged in a competent manner. It also discusses the types of conditions which may interfere with competence to stand trial.     

法庭语音学

本文对法庭语音学进行了研究综述,主要介绍了该学科的核心内容:说话人鉴定。在实际办案中,当未找到嫌疑人,只有犯罪分子的检材语音时,可以使用说话人画像/说话人分类技术。若没有犯罪分子的录音证据时,可以让受害人和证人进行说话人的听觉辨认。具体的辨认形式有两种:对熟人辨认和对陌生人辨认,在对陌生人辨认时可以采用语音辨认的方法进行。当检材语音和样本语音都齐备的时候,法庭语音分析专家就可以对二者进行比对检验了。目前语音比对分析涉及到的问题和领域有:基于贝叶斯方法的法庭推理和似然比计算、共振峰频率的测量应用、非解析感知与样例理论、法庭说话人自动识别以及不同方法的综合应用等。     

犯罪剖绘:科学还是艺术?

犯罪剖绘(criminal profiling)为分析(连续)犯罪行为型态的技术,藉由统计技术分析潜在犯罪者、被害者与犯罪现场迹证等三者之间相互联结可能性。然犯罪剖绘技术应用至案件连结分析,可根据犯罪现场所遗留迹证(含心理迹证),预测/推论犯罪者之人口背景特征,并将这些案件之犯罪现场迹证系统化处理,建构成数据库,有助警察侦办连续型犯罪。经由案件连结分析所得证据,能否成为法庭上论罪之依据,在英美国家必须通过Frye法则与Daubert测试法则检验,即是否已经通过科学性检验,或同一学术领域同侪认可验证过程。因此,后续研究可朝更精确统计分析方法迈进,以提升案件连结分析数据库对于预测未发现犯罪者之准确率及其法庭证据力。     

Paternity probability when a relative of the father is an alleged father

When scientists use DNA evidence in court, coancestry effects such as population structure and relatedness are usually ignored. In paternity cases, only if a particular man has the child's paternal allele at a certain locus, can he not be excluded in the paternity dispute. However, it is certainly true that close relatives will be far more likely to have the child's paternal allele than will random members of the reference population. In particular, the probability that the true father's brother has the paternal allele is very much greater than that for any other relationship. In this paper, the authors describe a method for inference in a case where the true father may be a relative of the alleged father. This paper also reports that most current methods overstate the probability that the alleged father is the father.     

Assessment of forensic findings when alternative explanations have different likelihoods—“Blame-the-brother”-syndrome

Assessment of forensic findings with likelihood ratios is for several cases straightforward, but there are a number of situations where contemplation of the alternative explanation to the evidence needs consideration, in particular when it comes to the reporting of the evidentiary strength. The likelihood ratio approach cannot be directly applied to cases where the proposition alternative to the forwarded one is a set of multiple propositions with different likelihoods and different prior probabilities. Here we present a general framework based on the Bayes' factor as the quantitative measure of evidentiary strength from which it can be deduced whether the direct application of a likelihood ratio is reasonable or not. The framework is applied on DNA evidence in forms of an extension to previously published work. With the help of a scale of conclusions we provide a solution to the problem of communicating to the court the evidentiary strength of a DNA match when a close relative to the suspect has a non-negligible prior probability of being the source of the DNA.     

疑罪问题研究

疑罪是指在刑事诉讼活动中,因证据不足而对犯罪嫌疑人、被告人是否构成犯罪以及罪行轻重、此罪彼罪与一罪数罪等方面难以作出正确判断的情况。疑罪的基本特征是证据不足。疑罪可分为罪与非罪之疑罪、情节轻重之疑罪、此罪彼罪之疑罪和一罪数罪之疑罪。疑罪产生的原因是多方面的。认定疑罪要注意与疑难刑事案件相区别,把握好疑罪的认定标准,掌握好疑罪的处理原则:罪与非罪之疑适用疑罪从无;情节轻重之疑、此罪彼罪之疑和一罪数罪之疑适用疑罪从宽。贯彻好疑罪的处理原则有着重要的理论和实践意义。文章还就刑事诉讼各阶段如何具体贯彻疑罪的处理原则提出了建设性的意见。     

法庭语音学

本文对法庭语音学进行了研究综述,主要介绍了该学科的核心内容：说话人鉴定。在实际办案中,当未找到嫌疑人,只有犯罪分子的检材语音时,可以使用说话人画像/说话人分类技术。若没有犯罪分子的录音证据时,可以让受害人和证人进行说话人的听觉辨认。具体的辨认形式有两种：对熟人辨认和对陌生人辨认,在对陌生人辨认时可以采用语音辨认的方法进行。当检材语音和样本语音都齐备的时候,法庭语音分析专家就可以对二者进行比对检验了。目前语音比对分析涉及到的问题和领域有：基于贝叶斯方法的法庭推理和似然比计算、共振峰频率的测量应用、非解析感知与样例理论、法庭说话人自动识别以及不同方法的综合应用等。     

刑事诉讼案件公开的反思与重构

尽管法律文本对刑事诉讼案件公开已有初步的规定,但是因为其尚不完善,导致司法运行中产生了诸多问题。其严重后果是影响了法官的独立决断和对嫌疑人的权利保护。要改变当前法官在审判中的尴尬境地,应当构建比较健全的刑事案件公开机制,保障公众权利与司法裁判之间的合理界限。     

Reform from within: the Grendon example

In Salduz v Turkey (27 November 2008, No. 36391/02), the Grand Chamber of the European Court of Human Rights (ECtHR) stated:

...in order for the right to a fair trial to remain sufficiently ‘practical and effective’… Article 6 § 1 requires that, as a rule, access to a lawyer should be provided as from the first interrogation of a suspect by the police, unless it is demonstrated in the light of the particular circumstances of each case that there are compelling reasons to restrict this right…The rights of the defence will in principle be irretrievably prejudiced when incriminating statements made during police interrogation without access to a lawyer are used for a conviction.     

犯罪剖绘：科学还是艺术？

犯罪剖绘（criminal profiling）为分析（连续）犯罪行为型态的技术,藉由统计技术分析潜在犯罪者、被害者与犯罪现场迹证等三者之间相互联结可能性。然犯罪剖绘技术应用至＂案件连结分析＂,可根据犯罪现场所遗留迹证（含心理迹证）,预测/推论犯罪者之人口背景特征,并将这些案件之犯罪现场迹证系统化处理,建构成数据库,有助警察侦办连续型犯罪。经由案件连结分析所得证据,能否成为法庭上论罪之依据,在英美国家必须通过＂Frye法则＂与＂Daubert测试法则＂检验,即是否已经通过科学性检验,或同一学术领域同侪认可验证过程。因此,后续研究可朝更精确统计分析方法迈进,以提升案件连结分析数据库对于预测未发现犯罪者之准确率及其法庭证据力。     

Likelihood ratios for complex mixtures with relatives

Likelihood ratios used for the analysis of complex DNA mixtures depend on a number of modeling assumptions and parameter estimates. In particular, the LR does not give information about the relative weight of the separate contributors for hypotheses conditioned on several contributors. An alternative is to evaluate the observed LR with respect to likelihood ratios expected under the defense hypothesis. Further, a p-value corresponding to the LR can be calculated. The p-value is the probability of observing a LR equally large or larger than the one observed, if the defense hypothesis is true. In this paper we investigate the distribution of likelihood ratios for mixtures with drop-in and drop-out and related contributors. Disregarding a plausible close relative of the suspect as an alternative contributor may overestimate the LR against a suspect.     

Who made the disclosure? Recorded discussions between children and caretakers suspecting child abuse

Within investigations of suspected child abuse, the child's account is often at the core of the judicial process. When analysing the child's account, it is therefore important to consider how parents may have discussed the suspected abuse prior to the official investigation. However, no studies up to the present time have investigated discussions in real cases where parents suspect that their children have been abused. We analysed a sample (N = 19) of recorded conversations between parents and their children, delivered to the police as evidence for alleged physical or sexual abuse. Analyses of the questions used and the information provided in the discussions showed that the parent's strategies when questioning their children were extremely leading and that in the majority of the cases, all new information was provided by the parents. In spite of this, the parents deemed the recorded conversations as records of the children's accounts. While the sample was small and likely to be unrepresentative of child abuse suspicions in general, the findings have important practical implications. The results indicate that when planning an interview in a case where the alleged abuse relies on what a child allegedly has told a parent, particular caution should be taken when referring to these conversations.