涉及死亡原因和死亡性质的信访案件数量一直位居公安机关所有信访案件首位。尽管公安机关各级刑侦部门不断规范工作方式、加大工作力度,仍然难以避免出现越访、重访、缠访。本文所指的刑侦疑难信访案件,是指涉及死亡原因、死亡性质的非正常死亡事件,经基层县、市两级公安机关刑侦部门核查,但信访人仍然不断信访的案件。笔者长期从事现场勘查、法医鉴定和刑事侦查工作,接触并办理了大量涉及刑事侦查和检验鉴定方面的信访案件,其中 The number of letters and petitions involving the cause of death and the nature of death has always been the highest among all petition cases handled by public security organs. Although the public security organs at all levels of criminal investigation departments continue to standardize their work methods and increase their efforts, it is still hard to avoid the more visits, revisit, and interviews. This refers to the criminal investigation suspicious case refers to refers to the cause of death, the nature of the death of an unnatural death by the grassroots counties and municipal public security organs criminal investigation department verification, but petitioners are still letters and visits. The author has long been engaged in on-the-spot investigation, forensic examination and criminal investigation work, contacted and handled a large number of petition cases concerning criminal investigation and examination and appraisal, among which