Identifying background microbiomes in an evidence recovery laboratory: A preliminary study

16S rRNA profiling of bacterial communities may have forensic utility in the identification or association of individuals involved with criminal activities. Microbial profiling of evidence may, in the future, be performed within environments currently utilised for human DNA recovery, such as a forensic biology laboratory. It would be important to establish the background microbiome of such an environment to determine the potential presence of human or environmental microbial signatures to assist forensic scientists in the appropriate interpretation of target microbial communities. This study sampled various surfaces of an Evidence Recovery Laboratory (ERL) on three occasions including (a) before a monthly deep-clean, (b) immediately following the deep-clean, and (c) immediately after the laboratory’s use by a single participant for the purposes of routine item examinations. Microbial profiles were also generated for the involved participant and researcher for comparison purposes. Additionally, human nuclear DNA was profiled for each of the samples collected, using standard forensic profiling techniques, to provide a prospective link to the presence or absence of a background microbial signature within the ERL after its use. Taxonomic distributions across ERL samples revealed no consistent signature of any of the items sampled over time, however, major phyla noted within all ERL samples across the three timepoints were consistent with those found in human skin microbiomes. PCoA plots based on the Unweighted Unifrac metric revealed some clustering between participant microbial reference samples and surfaces of the ERL after use, suggesting that despite a lack of direct contact, and adherence to standard operating procedures (SOPs) suitable for human DNA recovery, microbiomes may be deposited into a forensic setting over time. The reference samples collected from the involved participant and researcher generated full STR profiles. Human DNA was observed to varying degrees in samples taken from the ERL across each of the sampling timepoints. There was no correlation observed between samples that contained or did not contain detectable quantities of human nuclear DNA and microbial profile outputs.     

Bloodstain pattern analysis & Bayes: A case report

The findings from a bloodstain pattern analysis (BPA) may assist in formulating or falsifying scenarios that are considered in the investigative stages of a criminal investigation. When a case proceeds to trial the bloodstain pattern expert may be asked about the relevance of their findings given scenarios that are proposed by the prosecution and defense counsel. Such opinions provided by an expert are highly relevant to police investigation or legal proceedings, but the reasoning behind the opinion or implicit assumptions made by the expert may not be transparent.A proper framework for the evaluation of forensic findings has been developed since the late twentieth century, based on the hierarchy of propositions, Bayesian reasoning and a model for case assessment and interpretation. This framework, when implemented in casework, mitigates some of the risks of cognitive biases, and makes the reasoning and scientific basis for the opinion transparent. This framework is broadly used across forensic science disciplines. In this paper we describe its application to the field of BPA using a case example from the Netherlands Forensic Institute (NFI).     

基于网络色情犯罪论坛数据库的取证系统研究

随着信息技术的不断发展,网络色情犯罪越来越严重,如何获取与计算机犯罪相关的电子证据,将犯罪分子绳之以法,已是迫切需要解决的问题。     

计算机犯罪现场中的取证技术及应用

科学有效地应用计算机取证技术是侦办计算机犯罪案件的关键。计算机取证也称为计算机法医学,是把计算机运行环境看作是犯罪现场,运用相关的辨析技术,对计算机犯罪行为进行法医式的解剖,从而搜寻确认罪犯及犯罪证据,并据此提起诉讼。从理论上讲,计算机取证人员能否找到犯罪证据取决于有关犯罪证据是否被覆盖。但从海量的数据里面寻找蛛丝马迹是一件非常费时费力的工作,侦查人员必须具备相应的专业技能,并按照科学合理的步骤来实施计算机犯罪现场中的取证工作。     

Impacts of increasing volume of digital forensic data: A survey and future research challenges

A major challenge to digital forensic analysis is the ongoing growth in the volume of data seized and presented for analysis. This is a result of the continuing development of storage technology, including increased storage capacity in consumer devices and cloud storage services, and an increase in the number of devices seized per case. Consequently, this has led to increasing backlogs of evidence awaiting analysis, often many months to years, affecting even the largest digital forensic laboratories. Over the preceding years, there has been a variety of research undertaken in relation to the volume challenge. Solutions posed range from data mining, data reduction, increased processing power, distributed processing, artificial intelligence, and other innovative methods. This paper surveys the published research and the proposed solutions. It is concluded that there remains a need for further research with a focus on real world applicability of a method or methods to address the digital forensic data volume challenge.     

The impact of force,time, and rotation on the transfer of ammonium nitrate: A reductionist approach to understanding evidence dynamics

Empirical studies evaluating the conditions under which the transfer of forensic materials occurs can provide contextual information and offer insight into how that material may have been transferred in a given scenario. Here, a reductionist approach was taken to assess the impact of force, time, and rotation on the transfer of an explosive compound. An Instron ElectroPuls E3000 material testing instrument was used to bring porous and non-porous surfaces adulterated with an ammonium nitrate into direct contact with a human skin analogue, controlling for the force of contact, duration of contact, and rotation applied during contact. Quantifiable amounts of ammonium nitrate were recovered from all of the recipient surfaces demonstrating that ammonium nitrate is readily transferred from one surface to another, even when contact occurs for a short duration with a relatively low force. More particulates were transferred from non-porous surfaces onto the human skin analogue, but the amount of ammonium nitrate transferred did not depend upon the force of contact, duration of contact, or the amount of rotation applied. However, when contact occurred and involved rotation, a greater transfer of ammonium nitrate was observed, compared to those contacts occurring without rotation being applied. This approach complements more commonly-used holistic experiments that test multiple interacting variables in a realistic setting by isolating these variables, allowing them to be examined individually. This can be utilised to better understand the individual impact that specific variables have on the transfer of trace evidence in relevant crime reconstruction contexts.     

规范语境下口供补强规则的解释图景

补强规则中的口供是指证明案件主要事实的被告人供述,补强证据是口供外的其他法定证据,与口供没有同源性。借鉴域外的“罪体标准”和“可信性标准”,根据补强对象的不同可将口供补强模式划分为罪体印证补强模式、隐蔽性证据(细节)补强模式和口供事实补强模式。我国不宜采口供事实补强模式,但可结合罪体印证补强模式与隐蔽性证据补强模式,将补强对象范围限定在“结果、犯罪行为和主体同一”三个客观面。三个客观面的补强意味着案件事实认定上的两大效果:一是可判断“犯罪已发生,该人有参与”,以降低假案冤案出现的风险;二是口供的可信性得到补强,所涵盖的主要犯罪事实可推断为真。然而“部分为真则全部为真”的推断逻辑仍不免产生质疑,但口供补强规则是定罪规则,并不排斥仅有口供仍可认定案件的部分事实或情节。当然,为确保口供补强规则适用的可靠性,可从口供合法性以及供述动机等外部保障机制再行审查。     

The Direct and Cross-Examination of Complainants and Defendants in Rape Trials: A Quantitative Analysis of Question Type

This paper is a post-hoc examination of the questioning used in six rape trials. Questions asked in the evidence-in-chief and cross-examination of six complainants and five defendants were coded into different categories. The categories comprised "open", "closed", "leading", "heavily-leading" and "yes/no" questions; questions that are known to increasingly constrain witness responses. Additionally, the frequency of "multiple questions", and questions with "negatives" and "double negatives" were recorded; questions that witnesses have difficulty understanding. Broadly speaking, results showed that questions in both evidence-in-chief and cross-examination were of a constraining nature and allowed witnesses little opportunity to provide complete accounts of alleged events, particularly during cross-examination. Multiple questions were frequent although negatives were comparatively rare, and double negatives did not occur. Similar forms of questioning were used for complainants as for defendants, although more questions were asked of complainants than defendants in cross-examination. The results are discussed in terms of the adverse influence of these questioning strategies on the completeness and accuracy of witnesses' responses, and the similarity in "combativeness" of lawyers in their examination of complainants and defendants.     

析视频监控在刑事诉讼中的作用

新的刑讼法颁布实施后对刑事技术提出了更高的要求,案件如何能破得了、诉得上、判得了、取证成了关键的环节。以往单一的现场痕迹物证显得相当无力,如何将现场痕迹物证与其他证据形成一个完整的证据链、在零口供的情况下将犯罪分子绳之以法是当前刑事技术发挥更大作用的突破口。视频资料是刑诉法规定的证据之一,其中视频监控资料与现场物证相结合就能为证实犯罪,案件审理提供完整的证据链。