Estimation Of Postmortem Interval By Decomposed Brain Tissue

Background:Due to climate reasons,there are nearly 500 cases of decomposed corpses every year in Guangzhou,the postmortem interval is more difficult to estimate than that of fresh corpses.The postmortem interval is related to the scope of case investigation,case arrangement,and postmortem interval is often can not be determined in the first time in the basic level work.According to statistics,the average time of solving murder cases in Guangzhou in 2016,2017 and 2018 was 9.3 hours,8.4 hours and 7.2 hours respectively.As for the research on the inference of the death time of corrupt bodies,the literature at home and abroad generally focuses on the micro-morphological changes of tissues and the analysis of molecular levels.Therefore,this topic focuses on the timeliness and convenience of the inference of the death time of decomposed corpses.By retrospective study of cases with decomposed corpses that we already knew the postmortem interval,we observed the brain,heart,lung,liver and kidney.We find out that decomposed brain softened and pulpified very differently in different postmortem interval,The environment of brain is relatively stable and less affected by other factors,and we can make use of it to estimate the postmortem interval of decomposed corpses.Objective:By retrospective study of cases with decomposed corpses that we already knew the postmortem interval and simulation experiment,to find the way to estimate the postmortem interval by decomposed brain.Methods:1.Retrospective study of casesWe collected 73 cases with decomposed corpses that we already knew the postmortem interval,and observed the Macroscopic signs of decomposed brain during the autopsy,classify the decomposed level by the Macroscopic signs.2.Simulation experimentWe collected the cases which just happened,The cause of death in the case taken was shock,craniocerebral injury,Sudden cardiac death,Mechanical asphyxia.Take the brain from top of forehead during the autopsy,rapidly transferred in vacuo and cold.Divide the same area into two,cut the brain to approximately 3 cm×3 cm×2 cm tissue blocks and put them in a closed,transparent container,then place in 25℃ and 35℃ incubator.Photo record in Oh,4h,8h,16h,24h,36h,48h,72h,96h and classify the decomposed level by the Macroscopic signs.Observe until the shape and size of the brain does not change and recording the time.Statistical analyses were performed by SPSS 25.0.Results:1.Retrospective study on decomposed corpsesAll cases were divided into five causes of poisoned,shock,sudden cardiac death,drowned,mechanical asphyxia.Get the first death time of each group,the data under the partial division were missing.According to the statistical results of the simulation experiment,the difference of postmortem interval of decomposed brain tissue has no statistical significance,that is,the cause of death has no influence on the degree of decomposed brain tissue under the same temperature conditions.Therefore,the time of death first in spring,autumn and summer to reach each degree was compared,and obvious differences were found.According to statistics.The decomposed brain tissue has reached 3 days of fourth degree,5 days of fifth degree,7 days of six degree in spring and fall.The decomposed brain tissue has reached 2 days of fourth degree,2 days of fifth degree,4 days of six degree in summer.2.Degree of simulation experimentCount the time taken to reach each degree in the same cause of death and take the average,Get the degree of shock,sudden cardiac death,craniocerebral injury,mechanical asphyxia in 25 ℃ and 35 ℃.At 25℃,postmortem interval used for the decomposed brain tissue in the sh℃k group:It takes 0 hours to reach first degree,18.7 hours to reach second degree,29.3 hours to reach third degree,36 hours to reach fourth degree,56 hours to reach fifth degree,80 hours to reach sixth degree.At 35℃,postmortem interval used for the decomposed brain tissue in the sh℃k group:It takes 0 hours to reach first degree,8 hours to reach second degree,16 hours to reach third degree,20 hours to reach fourth degree,32 hours to reach fifth degree,72 hours to reach sixth degree.At 25℃,postmortem interval used for the decomposed brain tissue in the crani℃erebral injury group:It takes 0 hours to reach first degree,10.7 hours to reach second degree,28 hours to reach third degree,40 hours to reach fourth degree,56 hours to reach fifth degree,96 hours to reach sixth degree.At 35℃,postmortem interval used for the decomposed brain tissue in the crani℃erebral injury group:It takes 0 hours to reach first degree,5.3 hours to reach second degree,16 hours to reach third degree,21.3 hours to reach fourth degree,32 hours to reach fifth degree,72 hours to reach sixth degree.At 25℃S postmortem interval used for the decomposed brain tissue in the sudden cardiac death group:It takes 0 hours to reach first degree,18.7 hours to reach second degree,32 hours to reach third degree,44 hours to reach forth degree,64 hours to reach fifth degree,88 hours to reach sixth degree.At 35℃,postmortem interval used for the decomposed brain tissue in the sudden cardiac death group:It takes 0 hours to reach first degree,6.7 hours to reach second degree,18.7 hours to reach third degree,22 hours to reach fourth degree,28 hours to reach fifth degree,72 hours to reach sixth degree.At 25℃,postmortem interval used for the decomposed brain tissue in the mechanical asphyxia group:It takes 0 hours to reach first degree,16 hours to reach second degree,36 hours to reach third degree,48 hours to reach fourth degree,72 hours to reach fifth degree,96 hours to reach sixth degree.At 35℃,postmortem interval used for the decomposed brain tissue in the mechanical asphyxia group:It takes 0 hours to reach first degree,5.3 hours to reach second degree,16 hours to reach third degree,18 hours to reach fourth degree,21.3 hours to reach fifth degree,52 hours to reach sixth degree.3.Time comparison of each degree in four death groupUsed statistical analysis about the time taken to reach each degree in Sudden cardiac death,mechanical asphyxia,shock,craniocerebral injury,there was no statistical difference between these four groups.At 25℃,It takes 24 hours to reach second degree in shock group,24 hours to reach second degree in craniocerebral injury group,24 hours to reach second degree in sudden cardiac death group,24 hours to reach second degree in mechanical asphyxia group.At 35℃,It takes 8 hours to reach second degree in shock group,4 hours to reach second degree in craniocerebral injury group,8 hours to reach second degree in sudden cardiac death group,4 hours to reach second degree in mechanical asphyxia group.At 25℃,It takes 36 hours to reach third degree in shock group,24 hours to reach third degree in craniocerebral injury group,36 hours to reach third degree in sudden cardiac death group,36 hours to reach third degree in mechanical asphyxia group.At 35℃,It takes 16 hours to reach third degree in shock group,16 hours to reach third degree in craniocerebral injury group,16 hours to reach third degree in sudden cardiac death group,16 hours to reach third degree in mechanical asphyxia group.At 25℃,It takes 41 hours to reach fourth degree in shock group,36 hours to reach fourth degree in craniocerebral injury group,48 hours to reach fourth degree in sudden cardiac death group,48 hours to reach fourth degree in mechanical asphyxia group.At 35℃,It takes 20 hours to reach fourth degree in shock group,20 hours to reach fourth degree in craniocerebral injury group,20 hours to reach fourth degree in sudden cardiac death group,20 hours to reach fourth degree in mechanical asphyxia group.At 25℃,It takes 48 hours to reach fifth degree in shock group,48 hours to reach fifth degree in craniocerebral injury group,72 hours to reach fifth degree in sudden cardiac death group,72 hours to reach fifth degree in mechanical asphyxia group.At 35℃,It takes 24 hours to reach fifth degree in shock group,36 hours to reach fifth degree in craniocerebral injury group,24 hours to reach fifth degree in sudden cardiac death group,24 hours to reach fifth degree in mechanical asphyxia group.At 25℃,It takes 72 hours to reach sixth degree in shock group,96 hours to reach sixth degree in craniocerebral injury group,96 hours to reach sixth degree in sudden cardiac death group,96 hours to reach sixth degree in mechanical asphyxia group.At 35℃,It takes 72 hours to reach sixth degree in shock group,72 hours to reach sixth degree in craniocerebral injury group,48 hours to reach sixth degree in sudden cardiac death group,48 hours to reach sixth degree in mechanical asphyxia group.4.Time comparison of each degree in 25℃ group and 35℃ groupUsed statistical analysis about the time taken to reach each degree in 25℃ group and 35℃ group in all cases within Sudden cardiac death,mechanical asphyxia,shock,craniocerebral injury.there was no statistical difference between these two groups.In all cases,At 25℃,It takes 16 hours to reach second degree in 25℃ group,8 hours to reach second degree in 35℃ group;It takes 36 hours to reach third degree in 25℃ group,16 hours to reach third degree in 3 5℃ group;It takes 48 hours to reach fourth degree in 25℃ group,20 hours to reach fourth degree in 35℃ group;It takes 72 hours to reach fifth degree in 25℃ group,24 hours to reach fifth degree in 35℃group;It takes 96 hours to reach sixth degree in 25℃ group,72 hours to reach sixth degree in 35℃ group.Conclusion:1.Decomposed brain tissue of softened and pulpified can be used to quantify and estimate the postmortem interval.2.The cause of death has no effect on the process of brain tissue decomposition,and the increase of temperature can accelerate the process of brain tissue decomposition.