The cultural labor of surveillance: video forensics,computational objectivity,and the production of visual evidence

This essay argues that the status of video evidence as an index of real events—a sign or representation that offers a direct, empirical connection to material reality—is the result of an intentional process of production. This process involves the repurposing of new technologies borrowed from the domain of creative media production in order to transform a chaotic field of raw surveillance video into useable evidence. In addition to the exchange in technologies, an unavoidable epistemological and interpretive exchange takes place between evidentiary uses of surveillance video on the one hand, and the now prevalent forms of surveillant narration found in both fictional and reality-based storytelling. But despite this exchange in meanings and technical systems, considerable effort has gone in to establish formal standards for the evidentiary uses of surveillance video that distinguish the discovery of video evidence from the production of creative content. Building on Daston and Gallison's historical study of the prevailing “epistemic virtues” that have defined objectivity over time, I argue that what we see emerging in the field of forensic video analysis, as a means of establishing its scientific and legal status, is a commitment to a new epistemic virtue of “computational objectivity.”     

05式警用转轮手枪弹壳接触DNA检验方法的比较

目的比较05式警用转轮手枪弹壳表面接触性DNA检验方法,为实际检验提供参考和借鉴。方法制备40例击发后手枪弹壳的模拟样本,分别用两步转移法提取弹壳表面不同部位检材,采用两种DNA提取法和两种扩增试剂盒对样本进行STR分型检验,比较评价检验结果。结果避开发射药残留区域采用两步转移法提取样本,有助于提高检出率;Chelex-100联合Microcon-100法提取模板DNA的产量最高可达1.18ng,高于Mini M48试剂盒法(0.91ng);MiniFilerTM试剂盒的等位基因检出率(23.61%)高于IdentifilerTM试剂盒(6.41%)。结论采用选择适当区域提取检材,采用Chelex-100联合Microcon-100法提取DNA,经MiniFilerTM试剂盒扩增,进行弹壳接触DNA分型的效果较好。     

3种甲醛固定组织DNA提取方法的比较

目的对不同方法提取甲醛固定组织中DNA的效果进行比较,寻找一种操作简便、经济实用、质量较高的DNA提取方法。方法取甲醛固定的心肌组织14份,分别以改良酚-氯仿法,改良Trizol法,试剂盒法提取DNA,进行紫外分光光度计测定OD260/OD280值后,经PCR扩增,琼脂糖凝胶电泳分析确定提取的DNA质量。结果改良酚-氯仿法,改良Trizol法,试剂盒法OD260/OD280比值分别为1.841 5±0.380 4、1.370 5±0.336 7、0.831 6±0.175 0。两两比较均有显著性差异(P<0.05)。3种不同方法提取DNA含量分别为0.943 8±0.530 1、0.707 5±0.423 6、0.342 8±0.182 5。PCR扩增后琼脂糖凝胶电泳显示以改良酚-氯仿法所提DNA的谱带清晰度好于其它两种方法。结论改良酚-氯仿法简便有效,所用试剂价格低廉,是一种经济实用的甲醛固定组织DNA提取方法。     

人体不同体液内PSA含量及其法医学意义

目的检测人体不同体液内前列腺特异抗原(PSA)含量,探讨其法医学价值。方法收集成年人(19～63岁)晨尿40份(男28份、女12份)、血液58份(男45份、女13份)、唾液25份(男14份、女11份);青少年(10～15岁)男性晨尿205份;哺乳期(25～31岁)女性乳汁9份;使用Cobas e411型全自动电化学发光免疫分析系统及T-PSA定量测定试剂盒,检测各样本T-PSA含量;分析不同体液及不同年龄青少年男性尿液PSA含量差异。结果除男、女性唾液外,其它样本均可检测到PSA,其中成年男性尿液含量最高,与其它体液比较具有显著性差异(P<0.000 1);青少年男性各年龄组尿液PSA含量随年龄逐年增高,11岁及以下年龄组含量不足1ng/mL,14岁及以上年龄组可超过1 000ng/mL。结论前列腺发育成熟的男性尿液PSA含量较高,在进行精液斑的法医学检验时应给予充分注意。     

人体组织/体液来源的法医学鉴定

生物检材的组织/体液来源鉴定是法医学检验的重要内容之一。法医学组织/体液鉴定的方法较多,无论是基于酶促反应或免疫学检测的传统鉴定方法,还是光谱法或近年来基于mRNA、microRNA或DNA甲基化差异的分子生物学组织鉴定技术,均各有特点。本文就各种法医学组织/体液鉴定方法的特点及其法医学应用价值作一简要综述。     

论纪检监察机关办案方式的调整——以刑事诉讼法的最新修正为背景

2012年刑事诉讼法修正案将对纪检监察机关的调查取证活动和现有的办案模式产生一定的影响。为实现纪检监察程序与刑事诉讼程序的无缝对接,需要对纪检监察机关的调查取证方式和办案模式进行必要调整。在调查取证方面,应当提高调查取证程序的规范性,加强对被调查人基本权利的保障,保证所取证据在刑事诉讼中的证据能力,必要时还应对取证程序的合法性进行证明。在办案模式方面,应当与检察机关建立新型的合作分工关系,在证据收集及程序进行方面对检察机关予以协助,并参与相关的诉讼活动。     

Forensic Comparison of Soil Samples Using Nondestructive Elemental Analysis

Soil can play an important role in forensic cases in linking suspects or objects to a crime scene by comparing samples from the crime scene with samples derived from items. This study uses an adapted ED‐XRF analysis (sieving instead of grinding to prevent destruction of microfossils) to produce elemental composition data of 20 elements. Different data processing techniques and statistical distances were evaluated using data from 50 samples and the log‐LR cost (C_llr). The best performing combination, Canberra distance, relative data, and square root values, is used to construct a discriminative model. Examples of the spatial resolution of the method in crime scenes are shown for three locations, and sampling strategy is discussed. Twelve test cases were analyzed, and results showed that the method is applicable. The study shows how the combination of an analysis technique, a database, and a discriminative model can be used to compare multiple soil samples quickly.     

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.     

Sexual violence perpetrated against women in India: the role of forensic evidence

ABSTRACT

In response to the upsurge in acts of sexual violence against women in India, Parliament passed the Criminal Law (Amendment) Act of 2013, amending existing statutes and rules of evidence relating to crimes of sexual violence and the practices of forensic professionals in the country. While a step in the right direction, this law paid little attention to forensic evidence in sexual violence cases, which can provide a more objective, scientific account of events, aid in the reconstruction of crimes, and help strengthen cases against perpetrators. The objectives of this article are twofold: to raise awareness for the need for a more prominent role of forensic evidence in sexual violence cases and to recommend ways to establish uniform and comprehensive policies and procedures on the collection and preservation of forensic evidence in order to ensure that cases of sexual violence against women are heard in Indian courts.     

开发高灵敏度血痕发光试剂用于法医现场检测

目的开发高灵敏度血痕发光试剂用于法医现场检测。方法本项目通过借鉴ECL发光的原理,通过化学电子链的乒乓共轭激活原理,使用均匀设计实验方法优化条件,合成多个新化合物,开发出新型高灵敏度血痕发光试剂。结果本项目开发的高灵敏度血痕发光试剂灵敏度高,发光时间长,在血液稀释1000倍的情况下,使用Chemi Scope3300化学发光成像系统读取荧光值,经过灰度转化最高值达到56,发光时间达到10分钟。结论本项目成功开发了高灵敏度血痕发光试剂,可以应用于法医现场检测。