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。     

Storage time for criminal trace evidence

The article discusses the question if and under what conditions trace evidence may be stored for DNA analysis. The authors report on several cases in which methodological improvements or even the introduction of DNA technology itself helped to identify the perpetrator or to rule out a suspect, who may already have been wrongly convicted, many years after the offence. Under medical and scientific aspects these cases seem to speak in favour of unlimited storage. German law does not contain explicit regulations on the storage of trace evidence of unknown origin, although it seems admissible under existing law. In view of a minor need of protection as against a high interest in the preservation of trace evidence, storage for an unlimited period of time seems necessary.     

纤维物证检验技术的现状及发展

本文概述了国内外纤维物证的发现、提取和检验方法及研究进展,并针对我国不少地区刑侦部门在现场勘查和物证检验中对纤维物证重视不够等问题,提出我国纤维物证研究应以现场发现方法、综合检验技术研究及数据库建设为主要方向。     

Histologic evidence of repetitive blunt force abdominal trauma in four pediatric fatalities

In cases of acute fatal child abuse, certain injuries, including cutaneous blunt force trauma, skull fractures, subdural hematomas, intra-abdominal hemorrhage, and retinal hemorrhages are common and well described in the pediatric and forensic literature. These gross findings at autopsy, when taken into consideration with scene investigation and interviews with caregivers, may indicate both a clear manner and cause of death. In such cases, the discovery of additional pathologic changes attributable to older abusive injuries helps support a conclusion of death due to inflicted trauma. We discuss four cases of fatal child abuse in which acute blunt force abdominal trauma was the cause of death. In each of these cases, careful examination with proper sectioning and microscopy of select abdominal tissues revealed that the acute tissue trauma was superimposed on a background of older, healing injury. This older trauma was characterized by classic histologic elements of tissue repair, including fibroblast proliferation, early scar formation, increased vascularity, and hemosiderin-laden macrophages. Iron and trichrome stains were used to confirm the presence of hemosiderin and fibrosis in all four cases, but the recognition of fibroblast proliferation and a reactive vascular pattern was best seen on routine hematoxylin and eosin stains. The gross and microscopic autopsy findings, along with available investigative information, established the diagnosis of chronic physical abuse.     

Analysis with the Combur-Test--special aspects in forensic trace examination

The Combur Test is a ready-made and easy-to-use pretest for blood. It is based on the oxidation of tetramethylbenzidine (TMB), which is catalysed by haemoglobin and its derivatives. Despite its high sensitivity, there are many known substances which are responsible for false positive and false negative test results. On the basis of experiments of our own, case reports and the pertinent literature special aspects of the application of the Combur Test in the forensic routine case work are discussed.     

泥土物证检验技术的现状及发展

本文综述了国内外泥土物证的检验方法。针对目前我国泥土物证多,但发现提取送检的少;泥土成分多,但被检验的成分少的特点,提出泥土物证检验应向小样品量、多参数综合检验方向发展的观点,以求引起更多同行的关注,充分发挥泥土物证在侦破案件、证实犯罪中的作用。     

Collection of trace evidence from bombing victims at autopsy

The body recovered from the scene of a bombing may contain important trace evidence that links the suspect to the crime. Recognizing the lack of guidelines for evidence removal from the body, we have prepared a protocol to guide the pathologist in the collection of trace evidence from the bombing victim. Case material used in the development of the protocol included 13 bombing fatalities reported to the St. Louis Medical Examiner's Office since 1975.     

民事庭审质证的基本要素研究

民事庭审质证是质证双方在法庭主持下就证据的证明力和可采性进行相互辩驳的诉讼行为,其基本要素包括质证主体、质证客体、质证内容和质证方式四个方面。质证主体应是证据或其形成过程的认识者、质证意思的独立表示者、质证程序的参与者、质证行为的实施者、与质证相关的程序性权利的享有者或程序性义务的承担者,其不但包括当事人,而且包括广义上的证人。质证客体的范围应限于“当事人提出质疑的证据”,过宽或过窄均不利于兼顾司法公正的实现和诉讼效率的提升。质证内容应限于证据的真实性、关联性和合法性三个方面,证据的客观性缺乏质证意义,充分性只有在证据链中才有质证意义。质证方式亦即质证的行为方式,其有别于质证的基础性工作,是质证双方针对证据的证明力及其可采性展开的法庭论辩。     

Investigating polyurethane foam as a form of trace evidence.

The aim of this study was to determine whether polyurethane (PU) foam fragments from different sources could be discriminated from each other. Low and high power microscopy was used to determine whether or not foam fragments were distinguishable from each other under various lighting conditions. Once similar foam fragments were declared microscopically indistinguishable, the visible range microspectrophotometer was highly competent in further distinguishing the spectral characteristics in various fragments from each other. Foam fragments from the same source were shown to display no microscopical or chemical variation. Conversely, it was possible to make clear distinctions between foam fragments from different sources.     

Macroscopic assessment of environmental trace evidence dynamics in forensic settings

Environmental trace evidence offers useful circumstantial intelligence to link persons and scenes of forensic interest. An increasing empirical research base is dedicated towards understanding the transfer and persistence dynamics of environmental indicators including pollen, soils, and diatoms, within a diverse range of experimental frameworks. This paper presents two discrete studies exploring transfer and persistence of soils and sediments on footwear and diatomaceous earth adhered to clothing in forensically pertinent scenarios. Variables including sediment type, foot position, clothing type, and body positioning were also explored throughout. Both experiments incorporated a field-based methodology during the sampling effort. Photographs were collected of an initial transfer sample and of a retained assemblage following hours, days, and up to one-week of wear, facilitating macroscopic assessment of trace evidence dynamics. All images were processed using accessible, open-source software before spatial analysis of evidence distribution within and temporal assessment (% retention) upon each evidential surface. The results highlighted consistent loss of transferred sediment from footwear with significantly greater retention of loamy clay soil than dune sand which was absent beyond 24 h of wear. Loss was not influenced by wearer gait but was more rapid from those areas of the shoe sole in direct contact with the ground. Diatomaceous earth was retrieved from all three clothing types tested after one week – significant losses of material occurred before 48 h with a consistent assemblage identified beyond this. Denim was significantly more effective than acrylic and fleece for diatomaceous earth retention and significantly more material was lost from clothing worn on the lower body. These findings highlight the value of using visual environmental markers and a macroscopic analytical approach during the investigation of environmental trace dynamics. The methodology offers a novel, non-destructive assessment of soil and diatom transfer and persistence, complementing more extensive laboratory-based examinations to ensure the development of a well-rounded research base within the forensic sciences.     

高速瞬间摄影在物证检验中的应用实验

目的采用声、光、电瞬间感应触发的高速闪光成像装置,以普通数码相机拍摄物证瞬间变化形态,提高物证检验的有效性、客观性;方法研制专用摄影装置,包括触发装置、延时器和超高速闪光灯等组件。进行物证瞬间状态摄影实验,研究运动物体瞬间形态的拍照技术方法;结果本实验装置原理简单、有效。最高记录瞬间成像速度小于0.5μm。可以用于常规物证瞬间变化的成像摄影记录。     

从CTS能力验证计划看纤维物证检验的发展趋势

本文通过对2006年以来CTS法庭科学领域纤维测试项目结果的分析,总结了国内外纤维物证检验的技术方法,并对纤维物证检验的发展趋势进行了展望。     

Forensic examination and application of areca nuts as material evidence

In this study, we aimed to explore the possibility of DNA analysis of areca nut as material evidence and the value of short tandem repeat (STR) typing of areca nut as material evidence under the condition of simulating external environment. In this study, water soaking, soil burial, sun exposure, and wet environment were used to treat areca nut residues. Chelex 100 was used to extract DNA, the PowerPlex21 kit to amplify, and the ABI PRISM^® 310 Genetic Analyzer to analyze the DNA of areca nut residues. DNA and STR typing were performed to analyze the residue after chewing. The results showed that the number of residual sites decreased with time under the conditions of water soaking, soil burial, sun exposure, and wet environment. Thus, areca nut can be used as forensic material evidence for DNA analysis and individual identification.     

DNA profiling of trace evidence--mitigating evidence in a dog biting case

A young girl was the victim of a severe dog attack. An animal, suspected of having caused the attack, was later impounded for investigation. Microclots of blood, recovered from the dog's fur, were analyzed by STR DNA. Results showed that this blood was not related to the biting. Other forensic evidence--hairs, fibers, and odontology--failed to connect a particular animal to the attack. The implications of these findings for the dog and its owners are discussed as well as other forensic methods for resolving such cases.     

The potential transfer of trace DNA via high risk vectors during exhibit examination

As the sensitivity and discriminative power of DNA technology progressively improves, the ability to utilise trace DNA as evidence in forensic casework similarly increases. Along with increased sensitivity comes the prospect of detecting contaminating DNA, complicating the interpretation of profiles. This study aimed to provide data into the occurrence and level of DNA potentially transferred between high risk vectors (scissors, forceps, gloves) and exhibits during the examination process in both light and heavy contamination/contact scenarios. DNA transfer was observed for all vectors in both transfer situations, with heavy conditions transferring more than light. Profiles with sufficient alleles to identify the origin were observed for each vector in both heavy and light scenarios, excluding forceps, where only a small number of alleles were transferred under light conditions,     

Histologic diagnosis of sodomy

A case of homicidal strangulation with sodomy is presented. Without the use of a simple routine histologic technique, the diagnosis of sodomy could not have been unequivocally substantiated.     

Novel cellular signatures for determining time since deposition for trace DNA evidence

With the increase in sensitivity of DNA profiling, questions about how and when the DNA was deposited have become a driving issue in forensic cases. To address this, we propose a novel method to determine time since deposition of trace DNA samples based on morphological and autofluorescence properties of individual epithelial cells which can change as the sample ages. To develop this signature, a series of trace DNA samples were generated by contact/handling a substrate and then allowed to age anywhere between one day and more than one year prior to collection. Imaging flow cytometry (IFC) was then used to characterize the morphology and autofluorescence profiles of individual cells within each sample followed by multivariate modelling and predictive classification.Resultsshowed that epithelial cell populations could be classified with high accuracy (∼90%) into one of three time-since-deposition groups: < 1 week, between 1 week and 2 months, and > 2months. Differences across age groups were largely driven by decreases in brightfield contrast and increases in the intensity of autofluorescence. To further test this approach for forensic casework, 47 individual donor cell populations spanning each time deposition group were classified blindly against the remaining data set. Samples containing at least 75 cells and a posterior probability greater than 0.90 showed classification accuracies ∼95%. Accuracies for individual time groups were 97% (<1 week), 92% (1week-2months), 98% (>2 months) with an average posterior probability for all time groups ∼0.96. This indicates that autofluorescence and morphological analyses may provide probative information regarding time since deposition for many types of trace DNA samples in forensic casework.