[Research Progress on the Methodological System for Decomposition Stage Classification in Forensic Medicine]

Accurate classification of postmortem decomposition stages is a critical step in estimating the postmortem interval (PMI) and tracing the initial decomposition environment. Research on the decomposition staging methodological system is gradually shifting from empirical observation to the establishment of systems based on multidimensional quantitative indicators. This paper focuses on two key pathways, "macroscopic morphological evolution" and "microscopic molecular succession", and systema-tically reviews the evolutionary patterns and applicability of the decomposition staging system in three typical environmental media: surface exposure, burial, and aquatic systems. It also summarizes research progress in constructing stage classification models utilizing microbiome and metabolomic features. Furthermore, it highlights the integrated application of decomposition characteristic quantification techniques, multi-omics data integration, and machine learning algorithms in decomposition analysis systems. It analyzes the prospects and challenges of applying these approaches to build a standardized and practical decomposition staging system, aiming to provide theoretical support for establishing a decomposition staging system with high accuracy and strong adaptability to different environments.