Using ninhydrin to detect gravesoil

Some death scene investigations commence without knowledge of the location of the body and/or decomposition site. In these cases, it is necessary to locate the remains or the site where the body decomposed prior to movement. We hypothesized that the burial of a mammalian cadaver will result in the release of ninhydrin reactive nitrogen (NRN) into associated soil and that this reaction might have potential as a tool for the identification of clandestine graves. Juvenile rat (Rattus rattus) cadavers were buried in three contrasting soil types in Australian tropical savanna ecosystems and allowed to decompose over a period of 28 days. Soils were sequentially harvested and analyzed for NRN. Cadaver burial resulted in an approximate doubling (mean = 1.7 +/- 0.1) in the concentration of soil NRN. This reaction has great potential to be used as a presumptive test for gravesoil and this use might be greatly enhanced following more detailed research.     

Arid Climate Adipocere—The Importance of Microenvironment

Skeletal remains were retrieved from a cave in an arid desert environment. The submitted material consisted of dried grass, soil, and malodorous skeletal remains wrapped in leather. After examination, it was revealed that the smell had not been due to recent decomposition but to adipocere. The cause of death was listed as “undetermined” and a suggested date of death as “unknown.” Although adipocere usually requires a damp environment or submersion in water to develop, this case provides further evidence for the rare possibility of adipocere formation in an otherwise very dry environment. Wrapping of the body in leather material had produced an impermeable barrier which had sequestrated and preserved bodily fluids allowing anaerobic decay with fat hydrolysis and adipocere formation. Microenvironments may have potentially significant and quite idiosyncratic effects on decompositional processes which may initially confuse investigations.     

微量物证理化检验实验室认可工作的特点

文章结合我国微量物证检验工作的现状,对微量物证实验室认可工作的特点、难点以及认可中容易出现的问题进行了分析,在此基础上提出了具体的注意事项和建议。     

微痕量检验在致伤物推断与认定中的价值

致伤物可为侦查和审判提供准确、可靠的线索和证据。在法医学实践中,创内异物的分析与检测一直是致伤物推断和认定的重要途径之一。近年来,随着一系列先进检测技术的应用,使得致伤物在创周遗留的微痕量物证的发现和检验获得了重要进展。微痕量检验也由对火器伤射击残留物的分析扩展到钝器伤和锐器伤检验．并取得了初步的进展。     

The Effects of Soil Environment on Postmortem Interval: A Macroscopic Analysis

Abstract:  Burial environment, in particular soil moisture, has a significant impact on the type, rate, and extent of bone degradation, which ultimately affects estimations of the postmortem interval (PMI). The purpose of this research is to determine the effects of soil moisture on the color, weight, condition, and texture of bone as it relates to the PMI. Bone changes occurring over two different time intervals (2 and 5 months) were examined using 120 sus scrofa leg bones. During each time interval bones were buried in two soil environments, one of which was drier than the other. The bones in both environments lost weight over time but the net weight loss was greater for bones in the higher moisture environment. There was no change in color, texture, or overall condition, indicating that 150 days is not long enough for such alterations to occur, regardless of the moisture level of the burial environment.     

系列杀人案件的成因、特点及侦查对策

发生系列杀人案件的原因取决于作案人的犯罪心理,谋财害命、报复杀人、滥杀无辜和杀人灭口是导致系列杀人案件的主要成因。系列杀人案件的特点体现在作案人的行为特征、作案人的个性特征和犯罪现场的痕迹物证三个方面。在侦查过程中,应引进利用“软件”串并案件的理念以拓展串并案途径,过细勘查犯罪现场,建立失踪人口管理机制以及时发现和串并系列杀人隐案,严格遵循公安部“侦破系列杀人案件工作机制”的要求规范侦查工作,引入和加强犯罪心理画像、犯罪现场重建和辩证侦查思维等现代侦查和取证方法。     

车外人员与汽车碰撞事故现场痕迹特点分析

道路交通事故的发生是人、车、道路等因素综合作用的结果，碰撞过程中。三者之间在极短的时间内发生了强烈的相互作用，如制动、碰撞、损伤产生等。事故发生后。根据国家GA41—2005《道路交通事故痕迹物证勘验》标准规定。交通事故现场痕迹包括路面痕迹、车体痕迹、人体痕迹、其它痕迹等勘验是确定交通事故责任和成因的主要依据。本文研究中通过对200起车外无防御能力的道路使用者（行人、自行车、三轮车、摩托车）与汽车碰撞事故现场痕迹。如人一车一道路位置。车辆的制动印痕、行驶速度、碰撞痕迹，人体致伤特点等各种客观的信息参数．寻找易于提取、利于计算分析、有助于事故重建的现场痕迹参数特点。以此建立起基于现场痕迹信息综合处理的事故再现参数体系。为后续重建交通事故碰撞过程研究提供参考依据。     

Analysis of forensic soil samples via high-performance liquid chromatography and ion chromatography

Traditional forensic soil comparisons are performed via physical and/or chemical examinations of color, texture, and mineral content, leaving any organic- or water-soluble fractions unexamined. This study uses high-performance liquid chromatography (HPLC) and ion chromatography (IC) to assess the qualitative and quantitative variation in these fractions of soil. Soil samples (n=120) were collected over the course of 3 weeks from urban, suburban, and rural locations in and around Lansing, MI. Additional samples from six of these locations (two urban, two suburban, and two rural) were collected once a week for 10 weeks for temporal analysis. Nine additional samples, equally spaced over a 1 m(2) grid, from these same six locations were collected for spatial analyses. Qualitative and quantitative analysis of the resultant chromatograms separated the 120 samples into 10 groups by HPLC and 23 groups by IC. This study shows that using HPLC and IC to analyze the organic- and water-soluble fractions of soil can successfully discriminate samples. Quantitative analysis of the results eliminates some false inclusions by providing further differentiation of samples. The results of this study indicate that adding HPLC and IC analyses to traditional forensic soil analysis schemes can improve overall sample differentiation. The methods used in this study were also able to detect both qualitative and quantitative variations in soil over a relatively small geographic area. This demonstration of soil heterogeneity underscores the importance of the collection of a representative known sample population when assessing a forensic soil comparison. Significant temporal variation was also demonstrated over the course of 10 weeks of sampling; however, samples were found to be consistent over shorter periods of time. Baseline levels of inorganic anions were determined via IC; these levels may be useful in assessing the significance of anions detected in soil from cases involving low explosives.     

An investigation into the spatial elemental distribution within a pane of glass by time of flight secondary ion mass spectrometry

Advances in the technology employed for the manufacture of glass have resulted in a final glass product with little variability in terms of its physical and optical properties. For example, the refractive index of Australian float glass tends to lie between 1.5189 and 1.5194. It has therefore become necessary to complement physical and optical methods for forensic glass comparison with instrumental elemental analyses. In a previous study, time-of-flight secondary ion mass spectrometry has been shown to offer potential for the analysis of glass particles as small as a few tens of microns across. In this study, the three-dimensional homogeneity of a sheet of float glass is described, and consequences for forensic elemental analysis of glass particles of such size are explored. Variation in Si, Ca, Mg, and Na levels immediately under the nonfloat surface was observed, with the variance accompanied by a decrease in refractive index.     

Bayesian networks and the value of the evidence for the forensic two-trace transfer problem*

Forensic scientists face increasingly complex inference problems for evaluating likelihood ratios (LRs) for an appropriate pair of propositions. Up to now, scientists and statisticians have derived LR formulae using an algebraic approach. However, this approach reaches its limits when addressing cases with an increasing number of variables and dependence relationships between these variables. In this study, we suggest using a graphical approach, based on the construction of Bayesian networks (BNs). We first construct a BN that captures the problem, and then deduce the expression for calculating the LR from this model to compare it with existing LR formulae. We illustrate this idea by applying it to the evaluation of an activity level LR in the context of the two-trace transfer problem. Our approach allows us to relax assumptions made in previous LR developments, produce a new LR formula for the two-trace transfer problem and generalize this scenario to n traces.     

Journey history reconstruction from the soils and sediments on footwear: An empirical approach

The value of environmental evidence for reconstructing journey histories has significant potential given the high transferability of sediments and the interaction of footwear with the ground. The importance of empirical evidence bases to underpin the collection, analysis, interpretation and presentation of forensic trace materials is increasingly acknowledged. This paper presents two experimental studies designed to address the transfer and persistence of sediments on the soles of footwear in forensically relevant scenarios, by means of quartz grain surface texture analysis, a technique which has been demonstrated to be able to distinguish between samples of mixed provenance.It was identified that there is a consistent trend of transfer and persistence of sediments from hypothetical pre-, syn- and post-crime event locations across the sole of the shoe, with sediments from ‘older’ locations likely to be retained in small proportions. Furthermore, the arch of the shoe (the area of lowest foot pressure distribution) typically (but not exclusively) retained the highest proportion of grain types from previous locations including the crime scene. A lack of chronological layering of the retained sediments was observed indicating that techniques that can identify the components of mixed provenance samples are important for analysing footwear sediment samples. It was also identified that the type of footwear appeared to have an influence on what particles were retained, with high relief soles that incorporate recessed areas being more likely to retain sediments transferred from ‘older’ locations from the journey history. In addition, the inners of footwear were found to retain sediments from multiple locations from the journey history that are less susceptible to differential loss in comparison to the outer sole. These findings provide important data that can form the basis for the effective collection, analysis and interpretation of sediments recovered from both the outer soles and inners of footwear, building on the findings of previously published studies. These data offer insights that enable inferences to be made about mixed source sediments that are identified on footwear in casework, and provide the beginnings of an empirical basis for assessing the significance of such sediment particles for a specific forensic reconstruction.