法庭科学DNA实验室认可与质量控制

法庭科学DNA实验室认可是整个实验室认可活动的一个组成部分,是对法庭科学DNA实验室的质量管理水平和技术能力的一种国家及国际间的正式承认。本文从文件体系建立、测量溯源、方法的确认、能力验证、质量控制等5个方面,对DNA实验室在认可中存在的主要问题进行了分析,对法庭科学DNA实验室认可与质量控制进行了探讨。     

降解检材STR分型Ladder-Like条带形成原因的探讨

目的探讨降解DNA短串联重复序列PCR扩增产物在PAGE中Ladder-L ike条带的形成原因。方法用一组人工合成的不同长度的D8S1179DNA单链,模拟降解检材中的断裂DNA;利用John M设计的D8S1179引物对模拟模板的DNA单链进行PCR扩增,PAGE分离。结果不同模拟模板的DNA单链的组合可以扩增出不同的Lad-der-L ike条带。结论短串联重复序列Ladder-like条带是PCR过程中降解DNA多态区互补扩增的产物。     

在心理测试中犯罪心理画像的应用

犯罪心理画像作为一项将心理学和侦查相结合的技术,不仅对特定类型的案件侦破具有应用价值,在一般案件的侦破工作中,如果合理运用,同样能够发挥其应有的作用。     

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.     

Forensic databases,a perspective from the penitentiary centers of Spain

Scientific and technological progress in the field of forensic genetics is very useful in the resolution of criminal cases, but it entails the need for a deep ethical reflection, as the individual Fundamental Rights may be violated.This project aims to collect and compare the opinion of prisoners and prison officials on what characteristics the country's forensic database should have. In this context, 210 subjects were surveyed, 101 of them prisoners and the rest prison officials, from three different Spanish penitentiary centers.Among the results obtained, most prisoners and officials consider the national DNA database to be useful, and additionally, a 40% of the participants would support the integration of the profiles of the entire population. 64% considered it ethical to use the DNA profiles of the database as a tool for familial searching. Despite this, half of the respondents are concerned about the future uses of the DNA database.Integrating the opinion of these analyzed groups with other relevant judicial, scientific and ethical convictions, ensures the regulation between security and individual’s Human Rights.     

Radicalisation theories,policing practices,and “the future of terrorism?”

This article explores how theories of radicalisation have placed an emphasis on the development of an indicators-based approach to identify individuals who might engage in politically motivated violence. We trace how policing agencies have juxtaposed the search for indicators as a defence against criticisms of racial profiling. However, through an analysis of Canadian counter-terrorism training programmes, we demonstrate that the search for radicalisation indicators reaffirms pre-emptive and discriminatory security practices. We insist that despite efforts to theorise radicalisation outside of the practices of the “war on terror”, current trends risk rationalising prejudicial policing that affirms social exclusion and injustice.     

潜血印迹显现方法研究进展

潜血印迹一般出现在恶性刑事案件当中,能够反映与案件有关的多方面信息,对于同一认定和分析判断案情具有十分重要的作用,这就使得其显现成为现场勘查的一项必不可少的工作。然而,这也正是公安实践工作当中的难点所在。经过多年的实验研究,目前国内外针对于潜血印迹的显现方法主要包括光学显现法和化学显现法。综述了这些常用显现方法的研究进展,并且讨论了每种显现方法在实践工作当中的优势和不足。     

Droplet-based optical trapping for cell separation in mock forensic samples

Optical tweezers have a wide range of uses for mechanical manipulation of objects in the microscopic range. This includes both living and static cells in a variety of biomedical and research applications. Single-focus optical tweezers, formed by focusing a laser beam through a high numerical aperture immersion objective, create a significant force, which enables controlled transport of a variety of different cell types and morphologies in three dimensions. Optical tweezers have been previously reported to capture and separate spermatozoa from a reconstituted simulated postcoital sample. We report herein the development of a simplified, more efficient cell transfer protocol that can separate and isolate both spermatozoa as well as leukocytes, with similar efficiencies as those previously reported. The new cell transfer method was used to separate sperm cells from a reconstituted mixture of spermatozoa and vaginal epithelial cells, with complete STR profiles developed from 50 cells with little evidence of contribution from the female contributor to the mixture. This modified protocol was then used to separate 21 samples of enriched leukocytes, with trapped cells ranging from 5 to 22 cells. Complete STR profiles were developed from as few as 10 leukocytes. Thus, with minimal sample preparation and a short trapping time, this method has the potential to provide an alternative to traditional differential extraction methods for separation of sperm:nonsperm mixtures while also providing versatility for separation of cells with differing morphologies.     

Geographical profiling in a novel context: prioritising the search for New Zealand sex offfenders

The present work explores the utility and value of geographical offender profiling methodologies within a novel context, considering both theoretical and practical issues relating to their application. The effectiveness of a well-known geographical profiling system, Dragnet, was tested across 101 New Zealand sex offence series, and findings compared with those derived for an equivalent sample from the UK. Average search costs (the amount of the total offence area that needed to be searched, starting from predicted offender home location, before the offender's actual home was reached) were far greater for the New Zealand sample than their UK offending counterparts. It is argued that this is because the spatial behaviour of New Zealand offenders violates many of the assumptions that Dragnet and other similar geographical profiling systems make in predicting offenders' home locations. Calibration of the system to the specific home-crime distance patterns of the New Zealand offenders did not enhance the efficacy of predictions made to a significant extent. It is consequently argued that, in their current form, geographical profiling systems are limited in their ability to account for samples displaying very different spatial characteristics to those that they were developed from and for. The implications of these findings for the general utility of geographical profiling are discussed, and ways in which systems might be developed in order to broaden their scope and applicability are suggested.     

Stereotyping,congruence and presentation order: Interpretative biases in utilizing offender profiles

Abstract

This paper explores how offender profiles might influence the way in which individuals interpret investigative information dependent on its congruence with the investigators’ own beliefs. Participants, comprising 222 lay people, completed an online questionnaire where a profile was either congruent or incongruent with a stereotypical or an atypical suspect who was presented before or after the introduction of the profile (resulting in eight conditions). Several cognitive strategies appeared to be used in interpreting the information. Contrary to expectations, individuals relying on representativeness heuristics were more influenced by a profile challenging their views than by one supporting them, whilst individuals who invested greater cognitive effort (termed hereafter “cognitive elaboration”) were more resistant to changing their views in light of disconfirming profiling advice. There was tentative evidence to suggest that a confirmation bias might occur when individuals engage in cognitive elaboration, such that individuals appeared to be more influenced by a confirming profile than by a disconfirming one. Finally, it was found that the profile was perceived to be more influential when presented before the introduction of a suspect than after. Implications for advising on the interpretation of such advice, as well as preparing such reports, are discussed.