Blast Suppression Foam,Aqueous Gel Blocks,and their Effect on Subsequent Analysis of Forensic Evidence*

In addition to having blast mitigation properties, aqueous foam concentrate AFC-380 blast suppression foam is designed to capture aerosolized chemical, biological, and radioactive particles during render-safe procedures of explosive devices. Exposure to aqueous environments and surfactants may negatively affect forensic evidence found at the scene, but the effects of AFC-380 foam and aqueous gel on the preservation and subsequent analysis of forensic evidence have not previously been investigated. Sebaceous finger and palm prints and DNA samples on paper, cardboard, tape, and various metal and plastic items, along with hairs, carpet and yarn fibers, and inks and documents, were exposed to AFC-380 foam. Similar mock evidence was also exposed to a superabsorbent gel of the type found in aqueous gel blocks used for shrapnel containment. Exposure to foam or aqueous gel was associated with a dilution effect for recovered DNA samples, but quality of the samples was not substantially affected. In contrast, exposure to AFC-380 foam or gel was detrimental to development of latent finger and palm prints on any substrate. Neither the hair nor the fiber samples were affected by exposure to either the foam or gel. Indented writing on the document samples was detrimentally affected by foam or gel exposure, but not inks and toners. The results from this study indicate that most types of forensic evidence recovered after being exposed to aqueous gel or blast suppression foam can be reliably analyzed, but latent finger and palm prints may be adversely affected.     

移动设备电子搜查的制度挑战与程序规制——以英美法为比较对象

评估执法的正当需求和手机用户的合法权益成为移动互联网时代的程序规制命题。移动设备搜查对警察权力的重要性和公民权利保护的重要性日益凸显,应当将移动设备视为人们具有合理信赖的一个信息隐私空间。英国、美国的手机搜查规范上的域内不统一导致搜查实践的多样态、公民权利的保护缺陷。但其应对证据的移动电子化的基本思路——根据信息种类或其他变量进行立法,区别对待搜查条件——对中国相关搜查问题的解释和解决具有镜鉴意义。我国需要考虑确立获得搜查批准的原则,通过类型化规则给执法提供明确指导,并且明确搜查后的系列权利保障,进行电子搜查规则的适时调整与动态平衡。     

民爆公共安全概念之管见

民爆公共安全研究是一个全新的特色鲜明的课题,是我校为全面适应公安教育发展和山西公安工作需要而首创的。民爆公共安全是指非军事系统生产、流通、使用的具有爆炸性质的化工品涉及的不特定多数人的人身安全和重大公私财产安全,它是社会公共安全的重要组成部分。     

Android forensics: Automated data collection and reporting from a mobile device

In this research, a prototype enterprise monitoring system for Android smartphones was developed to continuously collect many data sets of interest to incident responders, security auditors, proactive security monitors, and forensic investigators. Many of the data sets covered were not found in other available enterprise monitoring tools. The prototype system neither requires root privileges nor the exploiting of the Android architecture for proper operation, thereby increasing interoperability among Android devices and avoiding a spyware classification for the system. An anti-forensics analysis on the system was performed to identify and further strengthen areas vulnerable to tampering. The contributions of this research include the release of the first open-source Android enterprise monitoring solution of its kind, a comprehensive guide of data sets available for collection without elevated privileges, and the introduction of a novel design strategy implementing various Android application components useful for monitoring on the Android platform.     

水压爆破装药量对界面约束程度影响分析

本文通过实验室测量不同装药量条件下有限水域水压爆破的压力波形,通过对压力波形的分析得出了装药量的变化对水-空气界面约束程度产生显著影响的结论。     

An Impact Velocity Device Design for Blood Spatter Pattern Generation with Considerations for High‐Speed Video Analysis,

A mechanical device that uses gravitational and spring compression forces to create spatter patterns of known impact velocities is presented and discussed. The custom‐made device uses either two or four springs (k₁ = 267.8 N/m, k₂ = 535.5 N/m) in parallel to create seventeen reproducible impact velocities between 2.1 and 4.0 m/s. The impactor is held at several known spring extensions using an electromagnet. Trigger inputs to the high‐speed video camera allow the user to control the magnet's release while capturing video footage simultaneously. A polycarbonate base is used to allow for simultaneous monitoring of the side and bottom views of the impact event. Twenty‐four patterns were created across the impact velocity range and analyzed using HemoSpat. Area of origin estimations fell within an acceptable range (ΔX_av = ?5.5 ± 1.9 cm, ΔY_av = ?2.6 ± 2.8 cm, ΔZ_av = +5.5 ± 3.8 cm), supporting distribution analysis for the use in research or bloodstain pattern training. This work provides a framework for those interested in developing a robust impact device.     

Analytical Characterization of Erythritol Tetranitrate,an Improvised Explosive

Erythritol tetranitrate (ETN), an ester of nitric acid and erythritol, is a solid crystalline explosive with high explosive performance. Although it has never been used in any industrial or military application, it has become one of the most prepared and misused improvise explosives. In this study, several analytical techniques were explored to facilitate analysis in forensic laboratories. FTIR and Raman spectrometry measurements expand existing data and bring more detailed assignment of bands through the parallel study of erythritol [¹⁵N₄] tetranitrate. In the case of powder diffraction, recently published data were verified, and ¹H, ¹³C, and ¹⁵N NMR spectra are discussed in detail. The technique of electrospray ionization tandem mass spectrometry was successfully used for the analysis of ETN. Described methods allow fast, versatile, and reliable detection or analysis of samples containing erythritol tetranitrate in forensic laboratories.     

The Palestinian intifada: An analysis of a popular uprising after seven months∗

This study challenges the conventional wisdom that the Internet is a reliable source of operational knowledge for terrorists, allowing them to train for terrorist attacks without access to real-world training camps and practical experience. The article distinguishes between abstract technical knowledge (what the Greeks called techne) and practical, experiential knowledge (mētis), investigating how each helps terrorists prepare for attacks. This distinction offers insight into how terrorists acquire the practical know-how they need to perform their activities as opposed to abstract know-what contained in bomb-making manuals. It also underscores the Internet's limitations as a source of operational knowledge for terrorists. While the Internet allows militants to share substantial techne, along with religious and ideological information, it is not particularly useful for disseminating the experiential and situational knowledge terrorists use to engage in acts of political violence. One likely reason why Al Qaeda and other Islamist terrorists have not made better use of the Internet's training potential to date is that its value as a source of operational knowledge of terrorism is limited.     

A Comparison of Common Swabbing Materials for the Recovery of Organic and Inorganic Explosive Residues

The efficiency of solvent based extraction methods used to remove explosive residues from four different swab types was investigated. Known amounts of organic and inorganic residues were spiked onto a swab surface with acetonitrile or ethanol:water combined with ultrasonication or physical manipulation used to extract the residues from each swab. The efficiency of each procedure was then calculated using liquid chromatography‐ultraviolet detection for organic residues and ion chromatography for inorganic residues. Results indicated that acetonitrile combined with physical agitation proved to be the most efficient method; returning analyte recoveries c. 95% for both alcohol based swabs and cotton balls. Inorganic residues were efficiently extracted using ethanol:water, while the use of acetonitrile followed by water significantly reduced the recovery of inorganic residues. Swab storage conditions were then investigated with results indicating decreased storage temperatures are required to retain the more volatile explosives.     

Quantified Explosives Transfer on Surfaces for the Evaluation of Trace Detection Equipment

Trace explosive test surfaces are often required for the evaluation of trace detection equipment to determine the equipment performance. Test surfaces of C‐4, Detasheet, Semtex‐H, TNT, and HMTD were prepared by transferring trace amount of explosive deposited on polytetrafluoroethylene (PTFE) transfer strips onto different surfaces (Kraft paper, hard plastic, woven fabric, and soft vinyl). The amount of explosive transferred was deduced from the amount of explosive remaining on the PTFE strips after transfer, as quantified by direct analysis using tandem mass spectrometry with thermal desorption. From the data set of over 2000 transfers, we experienced lower transfer efficiency for Semtex‐H and Detasheet, and for soft vinyl and hard plastic. However, the rapid quantification mass spectrometric method allowed the transfer efficiency to be determined for all test surfaces used in an evaluation of trace explosive detectors, thereby permitting only the test surfaces with desired transfer to be accepted for the assessment.