尸体是一个瞬时生态系统，其中软组织、昆虫、微生物从微观到宏观发生了复杂的变化且相互影响，尸体腐解变成白骨，从不平衡变为平衡。进行死亡时间（PMI）推断就是对该系统演化的各类变量的评估，其中昆虫指标已被证明对于PMI有价值并已应用，但仍存在某些时间段无法推断的缺陷，我们以往研究发现的昆虫关键时间点能保证对尸体划分出一个PMI范围，而利用分子、影像可望实现对于昆虫幼虫及蛹年龄的精确推断进而实现最短PMI的推断；新测序技术使得大量非培养微生物得到检测从而证明了微生物对于PMI推断的潜在价值，而软组织中的RNA也有着有限的规律变化。本项目拟利用猪尸体建立完整的尸体生态系统，对其中昆虫、微生物及软组织RNA的动态变化采用形态、组织、分子、电子计算机技术进行全局的系统研究，最终结合电子计算机技术形成以昆虫学为主,以微生物和RNA为辅的的针对陆地及水域尸体晚期PMI综合推断的新方法。

The cadaver in nature is an ephemeral ecosystem. Complex changes and interactions have taken place between soft tissues, insects and microbes, from micro to macro, makes a body from fresh turn into skeleton, and this cycle makes energy from the unbalance into a balanced state. The postmortem (PMI) estimation is essentially an assessment of the various variables in the evolution of the ecosystem. Insect indicators have been proven to be of value to PMI and have been applied widely, but there are still some fatal flaws as some time periods cannot be estimated using entomological method. Our previous study found that ‘the insect key milestones' can provide a range of PMI for most cadavers, and the use ofmorphology， molecular technology is expected to provide a precise age of insects, and thus achieved a more precise PMI estimation; The next generation sequencing technology allows a large number of uncultured microorganisms to be tested, and the potential value of microorganisms for PMI estimation is preliminary confirmed. The RNA in soft tissue has been proved to have a limited regular change. In this project, we intended to employ large pig carcasses to establish the carrion ecosystems, and conduct a comprehensive study on the dynamic changes of insects, microbes and RNA of soft tissue using morphological, histological, molecular biological ，ecological pproaches. The ultimate goal of this project is to establish a new PMI estimation method on land and under-water cadaver by mainly using entomological methods, and use the changes of microbial and RNA as supplementary indicators to confirm and compensate the entomological methods.