杀人分尸案的抛尸时间推断

尸体死亡时间的推断是法医现场勘查后首先需要解决的问题,早期死亡时间的推断主要依靠尸温的变化、尸体现象的变化等,晚期死亡时间的推断目前主要依靠法医昆虫学的知识来推断。笔者曾参与1起杀人分尸案的检验工作,在检验中充分利用蝇类的生长发育规律,进行合理分析,较准确地确定了死亡时间,为案件的侦破提供了非常有价值的线索。现将相关情况报道如下。     

西藏自治区中南部地区嗜尸性蝇类种类组成及分布

死亡时间(postmortem interval,PMI)推断一直是涉及人员死亡的刑事案件现场勘验中法医调查的重点和难点[1]。嗜尸性蝇类证据的应用是解决死亡时间推断特别是腐败尸体死亡时间推断的有效手段之一,但前提是要立足案发当地常见嗜尸性蝇类的种类及分布特点,并据此建立具体种类的发育史数据库。     

丽蝇科蝇类的生物学特性及其法医学应用

双翅目（Diptera）丽蝇科（Calliphoridae）蝇类是最早出现在腐败尸体、尸块上的主要蝇类。在法医昆虫学领域,根据丽蝇科的生活特性,可以较准确地推断出凶杀案或无名尸案的死亡时间（postmorteminter．val,PMI）,为案件侦破提供有利线索。本文介绍了丽蝇科蝇类的生物学、形态学特征,并对其在法医昆虫学与分子生物学、数学形态学、法医毒理学方面的联合应用进行了综述。     

嗜尸性蝇类种属鉴定研究进展

死亡时间(postmortem interval,PMI)推断一直是困扰法医学工作者的难题之一,尤其是荒郊野外或偏僻屋内的高度腐败尸体更是难以使用常规手段推断PMI,因此常需要借助现场中的昆虫证据来推断。不同种属的蝇类发育时间差异较大,在实际案件中,如果不进行种属鉴定而直接测量蝇蛆体长、计算积温或演替阶段,或是基于错误的种属鉴定来计算,往往会导致推算出的结果与实际PMI之间出现较大偏差,误导案件侦查方向。因此,使用法医昆虫学方法来推断腐败尸体PMI,必须先进行准确的昆虫种属鉴定。本文对嗜尸性蝇类不同虫态的大体和超微形态学种属鉴定以及分子生物学种属鉴定方法进行综述,以期为相关研究和实践提供新思路和新方法,为法医昆虫学在鉴定实践的应用推广提供参考。     

利用尸食性蚤蝇推断死亡时间的法医学研究进展

死亡时间的准确推断一直是法医学的难题。昆虫学方法已被认为是死亡时间推断的有效方法。尸食性蝇类发育生物学在死亡时间推断中有着重要地位。蚤蝇体形微小,在相对密闭的空间,可成为尸体上主要的甚至是唯一的昆虫证据。本文从尸食性蚤蝇的作用、种属鉴定以及日龄推断方面,综述了利用尸食性蚤蝇推断死亡时间的法医学研究进展。     

尸源性昆虫的法医学研究进展

尸源性昆虫学是应用昆虫学知识解决有关法律问题的法医学分支学科,对死亡时间的推断。特别是腐败尸体的死后间隔时间的推断等方面具有无可比拟的优越性。本文根据国内外近期法医昆虫学方面的研究进展,阐述了尸源性昆虫的研究历史、种类和侵蚀过程,并总结了尸源性昆虫形态学及分子生物学的种属鉴定方法。及近几年来在推断死亡时间方面的具体应用。就尸源性昆虫在法医学领域内的应用及进展进行综述。     

嗜尸性昆虫群落演替及其法医学应用研究进展

法医昆虫学是近年来法庭科学中发展较快的学科之一,而利用昆虫学证据来推断死亡时间或称死后经历时间(PMI)是其最主要的应用。当尸体PMI达一周以上,无法通过蝇蛆生长发育历期来推算时,仍可以借助嗜尸性昆虫群落演替规律来判断。嗜尸性昆虫群落演替规律与尸体腐败过程息息相关,法医昆虫学家通过对尸体腐败进行人为分期,能够辨别出不同的演替波次,从而达到推断PMI的目的。本文对嗜尸性昆虫群落演替研究与应用进行了综述,并分析了未来研究趋势,希望能为相关研究和实践应用提供参考。     

应用嗜尸性昆虫推断死亡时间11例

目的检验嗜尸性昆虫推断死亡时间的可行性及准确度,为鉴定实践提供参考。方法筛选11例已破案证实且昆虫学证据比较完整的案件,对案件中出现的昆虫种类、推断结果及真实结果进行统计和对比分析。结果案发现场所发现的昆虫包括大头金蝇、绯颜裸金蝇、乌足锡蝇、丝光绿蝇、厚环黑蝇、厩腐蝇、麻蝇(未鉴定具体种类)、蛆症异蚤蝇、黑水虻、丽腐阎甲、大隐翅甲、白腹皮蠹和赤颈郭公甲共13种。11例案件死亡时间均落在推断的时间范围内,其中72.73%的案件推断结果及真实结果在同一天。结论嗜尸性昆虫可以简单方便地推断死亡时间,死亡时间在蝇类或甲虫发育一代时间内的案件,推断结果比较准确,超过此范围,准确度降低。     

呼和浩特地区夏秋季常见嗜尸性蝇类的研究

目的研究呼和浩特地区常见嗜尸性苍蝇种类及其出现规律。方法观察法研究7～10月份兔尸上嗜尸性苍蝇种类变化。结果该地区兔尸上出现的双翅目嗜尸性苍蝇3科8属10种,主要有蝇科的家蝇、舍蝇、开普黑蝇、刺足齿股蝇、厩腐蝇;丽蝇科的丝光绿蝇、大头金蝇、铜绿蝇;麻蝇科的棕尾别麻蝇、肥须亚麻蝇。上述蝇类在尸体上出现时间及部位表现出很强的规律性。结论研究结果有望成为法医在呼和浩特地区对尸体进行死亡时间推断的依据。     

欧洲第四届法医昆虫学大会介绍与分析

第四届欧洲法医昆虫学会在意大利巴里召开,来自17个国家的代表参加了该会议,大会共接受论文65篇,该次会议论文主要集中于利用昆虫学推断死亡时间的新方法,昆虫演替对死亡时间推断的影响、法医昆虫毒物化学、新技术的应用等方面,反映了欧洲法医昆虫学研究已达到相当高的水平并开始了应用。我国迫切需要借鉴相关的经验促进我国法医昆虫学的发展。     

The Nocturnal Ovipositing Behavior of Carrion Flies in Cincinnati, Ohio

Abstract:  The behavioral patterns of nocturnal oviposition represent a window of time that potentially has a large impact on postmortem interval estimations. We investigated the behavioral patterns of carrion flies at night by exposing euthanized rats between sunset and sunrise to see if carrion flies oviposited upon the carrion over two consecutive summers. We investigated urban and rural locations, in both lit and unlit conditions with n  = 125. We found that nocturnal ovipositing did not occur in the Cincinnati metropolitan area. We conclude that nocturnal oviposition is an unlikely event in the Cincinnati metropolitan area.     

Estimating the preappearance interval from temperature in Creophilus maxillosus L. (Coleoptera: Staphylinidae)

Abstract: Some carrion insects appear on carcasses late in decomposition. While using these late‐arriving taxa to estimate postmortem interval, it is vital to accurately estimate an interval preceding their appearance on a cadaver called the preappearance interval (PAI). This paper tests the possibilities of a PAI estimation from temperature in case of late‐arriving, predatory carrion beetle Creophilus maxillosus. The relationship between temperature and PAI of adult and larval C. maxillosus was modeled using the results of a large‐scale experiment on succession in forests of Central Europe. In both stages, PAI was found to be strongly, inversely related to temperature averaged for the duration of PAI. The PAI estimation from mean degree‐day accumulations (mDDA), estimated DDA, and “PAI*T” functions were tested using external successional data. The greatest accuracy of PAI estimates was achieved using an exponential “PAI*T” function.     

A test for carrion fly full siblings: a tool for detecting postmortem relocation of a corpse

We propose a genetic test for full sibship for a pair of carrion flies that could reveal the postmortem relocation of a corpse. A carrion fly larva is sometimes left behind when a corpse is moved. The discovery of full sibling larvae of approximately the same developmental stage at two locations would strongly suggest that a corpse was moved between those two sites. Distributions of pairwise comparisons of relatedness (R) coefficients were generated using amplified fragment length polymorphism profiles for nine samples of laboratory-generated full siblings as well as for a reference sample of nonfull sibling Phormia regina (Diptera: Calliphoridae). The mean relative R coefficient, a pairwise measure of the proportion of shared alleles, was 0.479 (±0.289 SD) for full siblings, close to the theoretical expectation of 0.5. A likelihood ratio (LR) test was based on observed distributions of R. R >0.55 corresponded to an LR >1000 favoring full sibship for that pair of individuals.     

Black soldier fly (Diptera: Stratiomyidae) colonization of pig carrion in south Georgia

The black soldier fly, Hermetia illucens (L.), is thought to colonize corpses 20-30 days postmortem. However, recent observations indicate this might not be true for all cases. Therefore, we conducted a study examining colonization by the black soldier fly and other Diptera on pig carrion in a plowed field in southern Georgia from 20 September through 21 February. Our data indicate black soldier flies could colonize a corpse within the first week after death. Knowing this information could prevent a serious mistake in estimating the time at which a corpse is colonized by this species. This study also represents the first record of Chrysomya rufifacies in Georgia.     

丽蝇生长发育与死亡时间的相关研究

目的探讨丽蝇的生长发育与死亡时间的关系。方法在室外自然条件情况下,观察尸体腐败过程中来蝇时间,蝇的群集时间,产卵时间,蝇蛆的生长情况及成蛹、羽化时间,并联系气候因素收集数据,进行统计分析。结果来蝇时间发生在死后0.2h,死后28h苍蝇群集,在44h时发现虫卵,幼虫孵出时间为死后60h,入土化蛹时间为死后112h,羽化时间为248h。结论在尸体上观察丽蝇的生长发育不同的时间节点可用于推断死亡时间。     

Comparison of Protocols for Measuring and Calculating Postmortem Submersion Intervals for Human Analogs in Fresh Water

Protocols for determining postmortem submersion interval (PMSI) have long been problematic for forensic investigators due to the wide variety of factors affecting the rate of decomposition of submerged carrion. Likewise, it has been equally problematic for researchers to develop standardized experimental protocols to monitor underwater decomposition without artificially affecting the decomposition rate. This study compares two experimental protocols: (i) underwater in situ evaluation with photographic documentation utilizing the Heaton et al. total aquatic decomposition (TAD) score and (ii) weighing the carrion before and after submersion. Complete forensic necropsies were performed as a control. Perinatal piglets were used as human analogs. The results of this study indicate that in order to objectively measure decomposition over time, the human analog should be examined at depth using the TAD scoring system rather than utilizing a carrion weight evaluation. The acquired TAD score can be used to calculate an approximate PMSI.     

A Forensic Entomological Analysis Can Yield an Estimate of Postmortem Interval,and Not Just a Minimum Postmortem Interval: An Explanation and Illustration Using a Case

Several authors claimed that a forensic entomological analysis can never be interpreted as the postmortem interval (PMI), but that it can be interpreted as a minimum postmortem interval (PMI_min), or dead for not less than X amount of time. Because in most instances, a PMI estimate should be a range, that is, the set of values from maximum postmortem interval (PMI_max) to PMI_min, objections to PMI estimation are objections to PMI_max estimation. The arguments for this position did not address the substantial body of literature describing estimation of both PMI_max and PMI_min using insect succession analysis. This report reviews the scientific issues and presents a recent homicide investigation in which several forensic entomology experts used the absence of carrion insects on the corpse, a kind of succession analysis, to estimate PMI or PMI_max.     

Insect Successional Pattern of a Corpse in Cooler Months of Subtropical Southeastern Texas

Abstract:  Here, we characterize the cool weather insect fauna found associated with partially skeletonized and desiccated human remains recovered from an abandoned house in an urban area of subtropical, coastal Galveston County, Texas, and use the information to conclude an approximate postmortem interval of 7–10 months. The predominant factors that allow for a confident assessment of the postmortem interval include climatological data, entomological data, and anthropological data. The documented insect fauna represents a unique assemblage present in a particular environment (an urban abandoned house in coastal Texas) at a particular time of year (winter) and includes expected forensically significant insects such as calliphorid flies, muscid flies, and dermestid beetles but also includes less commonly encountered insects such as an unusually dense population of live case-making clothes moths.