Characteristics of Mechanical Asphyxia:A Retrospective Epidemiological Study in Two Developed Cities in China

Background:Mechanical asphyxia(MA)is multi-classified.Some epidemiological characteristics are shared and the others different among different MA types.Aims and Objectives:To reveal the characteristics of different types of MA and provide reference data for forensic identification of MA.Materials and Methods:We analyzed 913 cases to reveal the epidemiological characteristics of MA in Dongguan and Guangzhou,China.Results:Seven types of MA were identified and strangulation accounted for up to 89.2%.Those aged 20-29 were the most susceptible to all types,except for traumatic and positional asphyxia.Suicide accounted for 96.6%of hanging cases,and accident was the main manner of death in cases of choking,traumatic,and positional asphyxia.Homicide was the most common in cases of ligature strangulation(LS),manual strangulation(MS),smothering,and asphyxia concomitant with lethal mechanical injury.The homicide rate in LS was positively correlated with the rate of female victims(P<0.001,OR=21.14).In MS,the ratio of female:male was 101:15 in homicide.Compared to native residents,migrant workers were more likely to suffer from LS and MS.Rope was used in 50.8%of hanging cases,while LS tools were evenly distributed.Ligature marks were mostly found above the thyroid cartilage in both hanging and LS cases.The U shaped marks were shown in 51.01%of hanging cases but absent in LS cases.In LS,ligature marks completely encircling the neck,discontinuous marks,as well as≥two marks,were more(P<0.001)than in hanging.In LS and MS cases,abrasion and subcutaneous hemorrhages on the neck were more frequent than in hanging cases(P=0.004 and P<0.001),but the difference in frequency of blister marks was opposite(P<0.001).Conclusion:In summary,this study revealed the epidemiological characteristics of the MA cases in Guangzhou and Dongguan cities.The characteristics of death scene and autopsy findings are important in differentiation of different types of MA,especially between suicide and homicide.

Analysis of Indirect Evidence in Hit-and-run Cases

For personnel handling cases in public security bodies,evaluation of evidence is key to discover the fact and then to settle disputes.The process of evaluation shall be confirmed to rules of logic.Rules of logic are a set of judgment rules for people to reflect,induce,and deduce the development of law worldwide.Thus,evaluation of evidence shall be built on objective and rational logic deduction.Rules of logic applied in the investigation and judgment of evidence can help in finding a direct or indirect link between the evidence and the facts of an accident,thereby providing support and assistance for accident identification.It is particularly necessary to apply rules of logic to evaluate the indirect evidence chain in the investigation of hit‑and‑run traffic accident cases.This article demonstrates the specific application of such rules in the investigation of a serious hit‑and‑run traffic accident case.In the investigation process through the comprehensive analysis of and logical thinking around all indirect evidence,such as site inspection data,video monitoring data,witness testimony,and expert conclusions,and the combining of this with the direct evidence of the parties’statements,a complete chain of evidence for identifying a suspect’s vehicle and the accident facts can be formed.The effective application of rules of logic in the evaluation of the indirect evidence chain in hit‑and‑run traffic accident cases provides more clues and narrows the scope of an investigation,improving its efficiency and accuracy,thereby helping to identify the facts of an accident.