硅藻检验方法综述

水中尸体的调查在法医学检案中占了重要的一部分。水中尸体未必就意味着其死亡原因是溺死,也可以由其他原因引起,例如死后入水。实际上,尸体现象很难证明死亡的原因。所以,关于受害者是否为"真的"溺死的问题常常不容易解决。目前,硅藻检验被认为是溺死诊断的"金标准"。通过硅藻的定性定量分析,不仅可以对死亡原因有更直接的判断,也可以指向可能的溺死地点。本文介绍国内外硅藻检验的样本采集、检验方法、结果评价的研究进展,并对硅藻检验研究进行展望。     

溺死鉴定中硅藻检验的应用

在法医学检案中,溺死诊断以及入水地点的判定一直是重点和难点之一,硅藻检验被认为是一种相对可靠的诊断溺死的方法,而根据硅藻的群落特征推断其入水区域具有一定的可信度。对不同水域内硅藻进行研究,可为溺死鉴定及入水区域的判定提供参考。本文就硅藻相关的生物学特性、检验方法等相关的国内外研究进展进行综述,供法医学工作者在相关科研和检案实践中参考。     

广东珠江水域硅藻种类调查

目的应用扫描电镜对广东珠江水域水中硅藻进行观察,获得珠江水域硅藻种类情况及分布状况,结果有助于法医学水中尸体死亡原因及落水水域的推断。方法收集了广东省珠江水域19个取水点的水样,采用勒福特王水进行消解,并应用扫描电镜进行观察。结果 (1)19个采样点共检出直链藻、卵形藻、小环藻、菱板藻、菱形藻、双菱藻、针杆藻、冠盘藻、舟形藻、曲壳藻、圆筛藻、短缝藻、桥弯藻、海链藻、布纹藻、波缘藻、等片藻、辐节藻、双壁藻、异极藻和羽纹藻21种硅藻,分属于羽纹纲和中心纲。(2)获得19个采样点硅藻分布数据资料。结论 (1)珠江水域硅藻种类具有一定的特点。(2)不同河域硅藻种类、数量的差异有助于法医学推断溺死落水地点。     

An anthropological analysis of gunshot wounds to the chest

This analysis of gunshot trauma to the bony thorax examines 87 handgun and rifle wounds from documented cases in an effort to corroborate an earlier report and to provide the forensic community with additional literature in this area. Specifically, this study tests whether the trauma signatures associated with gunshot wounds in the bony thorax are useful in determining the direction of fire. Because the ribs occupy a significant portion of the bony thorax, they are struck more frequently than other bones and, consequently, they are the focus of this report. This study confirmed that bullets can leave distinctive markers on ribs that indicate the direction of fire, including depressed fractures, bone fragments displaced in the direction of the bullet's path, and beveling. Although forensic anthropologists can determine the direction that a bullet was traveling when it struck a given rib, they cannot give a definitive statement about the number or sequence of gunshots without supporting soft tissue evidence.     

Bodies found in the water. An investigative approach

The determination of the cause of death of a person whose body is found in the water requires careful investigative work on the part of both police and pathologists. Opinions as to cause and manner of death should not be derived from the autopsy alone but must result from a logical correlation of data regarding victim identity, circumstances, autopsy, and laboratory findings.     

Criminology and animality: stupidity and the anthropological machine

Although a relatively small, yet growing group of scholars have been lamenting the exclusion of nonhuman animals from the scope of criminology for over thirty years now, animals have been historically present in criminological theorizing, legal practices, and research. However, this presence has not been of the form advocated for by scholars who variously identify themselves as non-speciesist criminologists, green criminologists, or ecological criminologists, who have been arguing largely for recognition of harms perpetrated against animals, or ‘zoological crime’. Instead, the longer history of animals in criminology is as offenders or as prototypes of criminality. In this article, we are concerned with the production – vis-à-vis the anthropological machine – of the ‘stupid’ animal and subhuman within criminology and criminal justice. Guided by the political philosophy of Giorgio Agamben, we trace the animal through criminological thought from the premodern period to Lombroso to contemporary criminological scholarship illustrating how the animal has been (ab)used to shore up the classifications between humans, between humans and animals, and the intelligent and the stupid. We also examine how historically through criminal trials of animals and the feebleminded, criminal justice has played an active role in buttressing these classifications and acting on these classifications to produce bare life, that is, life without form or value.     

Metric variation in the human occipital bone: forensic anthropological applications

Sex and race variation of the occipital bone have been previously investigated, but particular examination of the effect of age and ancestry on sexual dimorphism has not been addressed. This paper examines morphological variation associated with sex and ancestry in the condylar region of the occipital bone and the effect of age and ancestry on the estimation of sex. Models previously published by Holland are also tested, and methodological problems are addressed. The results indicate that age does not have an effect on sexual dimorphism, but that whites exhibit greater, although not significantly, more sexual dimorphism than blacks. Significant sex and ancestry variation is present in the condylar region of the occipital bone, but neither sex nor ancestry could be estimated accurately using measurements of this anatomical region defined by Holland.     

Discrimination of pencil markings on paper using elemental analysis: an initial investigation

The characterisation and comparison of pencil markings on paper is an area of questioned document analysis that has previously not received much attention. Despite this, there would be value in an examiner being able to analyse two pencil markings and coming to a conclusion about whether they were from a similar or different source. Previous studies have analysed raw materials and bulk pencil cores for purposes of characterisation and differentiation, but to date, no studies have successfully analysed pencil markings non-destructively off a paper substrate. In this work, pencils from a number of manufacturers were analysed by inductively coupled plasma mass spectrometry (ICP-MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Analysis of data using multivariate techniques (principal component analysis), showed that ToF-SIMS can successfully be used to analyse such pencil markings to deduce whether two markings can be differentiated, in terms of inorganic elemental composition. It was possible to discriminate between pencil markings from different manufacturers, and it was also indicated that pencils from the same manufacturer, but discrete batches, can be significantly different.     

Time of death of victims found in cold water environment

Limited data is available on the application of post-mortem temperature methods to non-standard conditions, especially in problematic real life cases in which the body of the victim is found in cold water environment. Here we present our experience on two cases with known post-mortem times. A 14-year-old girl (rectal temperature 15.5 degrees C) was found assaulted and drowned after a rainy cold night (+5 degrees C) in wet clothing (four layers) at the bottom of a shallow ditch, lying in non-flowing water. The post-mortem time turned out to be 15-16 h. Four days later, at the same time in the morning, after a cold (+/- 0 degrees C) night, a young man (rectal temperature 10.8 degrees C) was found drowned in a shallow cold drain (+4 degrees C) wearing similar clothing (four layers) and being exposed to almost similar environmental and weather conditions, except of flow (7.7 l/s or 0.3 m/s) in the drain. The post-mortem time was deduced to be 10-12 h. We tested the applicability of five practical methods to estimate time of death. Henssge's temperature-time of death nomogram method with correction factors was the most versatile and gave also most accurate results, although there is limited data on choosing of correction factors. In the first case, the right correction factor was close to 1.0 (recommended 1.1-1.2), suggesting that wet clothing acted like dry clothing in slowing down body cooling. In the second case, the right correction factor was between 0.3 and 0.5, similar to the recommended 0.35 for naked bodies in flowing water.     

Cooling rates of the ear and brain in pig heads submerged in water: implications for postmortem interval estimation of cadavers found in still water

The state of the art for determining postmortem interval in submerged bodies reflects a serious lack of studies. The objectives of the present study were therefore to study cerebral and tympanic cooling in water and its relation to cooling in air, in a pig model. First of all, cerebral and tympanic cooling on a single head and on an entire body were compared and proven to be very similar in air and in water. Nine pairs of heads were then exposed to 9 temperature intervals from 0 degrees C to 20 degrees C. For every set temperature, one head was placed in water, the other in "ambient" air in a thermostatic chamber. Ear and brain temperature were simultaneously measured every 10 minutes during 8 hours. Results showed that both in air and in water, cooling curves were almost exponential, regardless of the site (ear or brain) or the environmental temperature. Cooling was always more rapid in water than in air. Cerebral and tympanic cooling always had a correlation coefficient of 0.98-0.99. Assuming that these cooling patterns are applicable to man, this research may provide a starting point for postmortem interval estimation in submerged cadavers.     

Circumstances and macropathologic findings in 1590 consecutive cases of bodies found in water

The diagnosis of drowning relies primarily on critical examination of the subject's individual characteristics, circumstances, and postmortem macropathologic changes. In this retrospective study, based on 1590 consecutive cases of bodies found in water and undergoing autopsy at the Department of Forensic Medicine, University of Helsinki, from 1976 to 1998, the frequency of circumstantial data and macropathologic changes crucial for the diagnosis of drowning were determined. The fatal events were eyewitnessed in 403 cases (25.3%), and suicide notes were found in 83 cases (5.2%). External foam, frothy fluid in airways, and overlap of the anterior margins of lungs were found in 275 (17.3%), 739 (46.5%), and 669 (42.1%) of the cases, respectively, but no one of these changes, tested against dry-land controls, were specific for drowning. The association of external foam and overlap of the lung margins was exclusive of drowning but was observed in only 176 cases (11.1%). After cross-analysis, 964 (60.6%) of the cases had no circumstantial data or macromorphologic pathologic findings that allowed a definite diagnosis of drowning. The diagnostic problems in putative drowning cases, based on this study sample, have not been overrated. Studies to investigate and improve the reliability of complementary methods for the diagnosis of drowning are warranted.     

Migrant deaths along the California-Mexico border: an anthropological perspective

California shares a 150-mile international border with Mexico. Traditionally, this border has seen non-stop illegal migration. In the 1990s, the Border Patrol began a concerted effort to establish and maintain control of the border, beginning in urban San Diego. This heightened law enforcement presence, known as Operation Gatekeeper, changed the westernmost segment of the border from the most permeable to the least permeable. This enforcement pushed migrants into more dangerous crossing areas in eastern San Diego and Imperial Counties, making their trip longer and more physically challenging as they made their way through treacherous mountains, deserts, and irrigation canals. Death rates soared. Political decisions impacted human lives and the caseloads of forensic anthropologists in jurisdictions along the border. Bodies decompose rapidly here, and there are minimal sources of antemortem data. Many of these migrants are never identified. This paper, and this symposium, is an attempt to bring this situation to the notice of other anthropologists and to discuss cooperative means of addressing the issue of identification.     

Multiple gunshot wounds of the head: an anthropological view

A decomposed body was judged at the scene to have two gunshot wounds of the thorax and three of the head. Confirmed at autopsy, the condition of the remains precluded conclusions about the precise nature of the defects. Preparation and reconstruction of the skull disclosed seven large cranial defects and a series of fractures. This preparation allowed the application of well-known principles of gunshot wound analysis. Although the analysis of specific gunshot wound defects is well covered in the literature, there are few examples of the application of gunshot wound principles to complex wound cases. Three entrances and three exits were identified. A seventh defect resulted from bullet passage. Finally, the wounds were sequenced.     

微波消解-扫描电镜联用法在溺死诊断中的应用

目的探讨微波消解-扫描电镜联用法在溺死诊断中的应用价值。方法收集已知死因的尸体标本105例,其中水中尸体85例(生前溺死70例,死后抛尸入水15例),陆地自然死亡尸体20例。水中死亡案例同时收集落水处水样。分别用微波消解-扫描电镜联用法(方法 A)和硝酸破机-光镜联用法(方法 B)对上述尸体的离体肺、肝、肾、骨髓组织及水样进行硅藻定性、定量检测。结果①溺死尸体的肺、肝、肾、骨髓中及落水处水样硅藻检出率:A法分别为100%、94.3%、92.9%、82.9%、100%,硅藻检验阳性率为100%;B法分别为90%、62.9%、51.4%、28.6%、92.9%,硅藻检验阳性率为65.7%。②两种方法检出的硅藻种类与落水处水样中硅藻的种类均一致。③两种方法在死后入水尸体离体的肺中也检出少量硅藻(<3个/2g肺组织),但在死后入水尸体的其它脏器及陆地自然死亡尸体脏器中均未检出硅藻。结论微波消解-扫描电镜联用法较硝酸破机-光镜联用法对尸体离体组织脏器中的硅藻检出率高,方法灵敏,定性准确。     

Typing of mitochondrial DNA coding region SNPs of forensic and anthropological interest using SNaPshot minisequencing

The development of new methodologies for high-throughput SNP analysis is one of the most stimulating areas in genetic research. Here, we describe a rapid and robust assay to simultaneously genotype 17 mitochondrial DNA (mtDNA) coding region SNPs by minisequencing using SNaPshot. SNaPshot is a methodology based on a single base extension of an unlabeled oligonucleotide with labeled dideoxy terminators. The set of SNPs implemented in this multiplexed SNaPshot reaction allow us to allocate common mitochondrial West Eurasian haplotypes into their corresponding branch in the mtDNA skeleton, with special focus on those haplogroups lacking unambiguous diagnostic positions in the first and second hypervariable regions (HVS-I/II; by far, the most common segments analyzed by sequencing). Particularly interesting is the set of SNPs that subdivide haplogroup H; the most frequent haplogroup in Europe (40-50%) and one of the most poorly characterized phylogenetically in the HVS-I/II region. In addition, the polymorphic positions selected for this multiplex reaction increase considerably the discrimination power of current mitochondrial analysis in the forensic field and can also be used as a rapid screening tool prior to full sequencing analysis. The method has been validated in a sample of 266 individuals and shows high accuracy and robustness avoiding both the use of alternative time-consuming classical strategies (i.e. RFLP typing) and the need for high quantities of DNA template.     

Typing of mitochondrial DNA coding region SNPs of forensic and anthropological interest using SNaPshot minisequencing

The development of new methodologies for high-throughput SNP analysis is one of the most stimulating areas in genetic research. Here, we describe a rapid and robust assay to simultaneously genotype 17 mitochondrial DNA (mtDNA) coding region SNPs by minisequencing using SNaPshot. SNaPshot is a methodology based on a single base extension of an unlabeled oligonucleotide with labeled dideoxy terminators. The set of SNPs implemented in this multiplexed SNaPshot reaction allow us to allocate common mitochondrial West Eurasian haplotypes into their corresponding branch in the mtDNA skeleton, with special focus on those haplogroups lacking unambiguous diagnostic positions in the first and second hypervariable regions (HVS-I/II; by far, the most common segments analyzed by sequencing). Particularly interesting is the set of SNPs that subdivide haplogroup H; the most frequent haplogroup in Europe (40–50%) and one of the most poorly characterized phylogenetically in the HVS-I/II region. In addition, the polymorphic positions selected for this multiplex reaction increase considerably the discrimination power of current mitochondrial analysis in the forensic field and can also be used as a rapid screening tool prior to full sequencing analysis. The method has been validated in a sample of 266 individuals and shows high accuracy and robustness avoiding both the use of alternative time-consuming classical strategies (i.e. RFLP typing) and the need for high quantities of DNA template.