Spectrophotometric Determination of Trimethylamine-nitrogen in Cadaver Tissues for the Estimation of Late Postmortem Interval:A Pilot Study

To study the relationship between the late postmortem interval （PMI） and trimethyl-amine-nitrogen （TMA-N） in postmortem tissues of cadaver, TMA-N in muscles, livers and kidneys of rats was measured at different postmortem intervals （PMI） by using a modified spectrophotometric method. The results indicated that the detection sensitivity of TMA-N was 1 mg/L, and there was a good linear correlation between the value of absorbance （A value） and TMA-N at the concentration of 1-10 mg/L （R2=0.9991）. Although TMA variation in muscles was different from that in inner organs during the time since death, TMA-N changes in cadaver tissues was positively correlated with PMI. During 2 to 7d since death, the best correlation between PMI and TMA-N concentration was found in muscles. With PMI as an independent variable, the cubic polynomial regression equation was y=-0.457x3 ＋6.519x2-24.574x＋27.207 （R2=0.969）. During 3 to 8 days since death, PMI was best correlated with TMA-N concentration in inner organs. With PMI as the independent variable, the cubic polynomial regression equation was y=0.509x3-9.153x2＋55.727x-95.819 （R2=0.953）. It was concluded that TMA-N in tissues could be used as a new estimator for late PMI. The method used in this study offered advantages such as accuracy, sensitivity, little samples required and wide PMI estimation.

Characterization of Protein in Old Myocardial Infarction by FTIR Micro-spectroscopy

The aim of the present study was to assess whether Fourier transform infrared spectrometry (FTIR) micro-spectroscopy could produce distinct spectral information on protein of old myocardial infarction (OMI) and to set them as molecular markers to diagnose atypical OMI. Paraffin-embedded heart samples were derived from victims dying of OMI. In combination with histological stain, FTIR and infrared micro-spectroscopy, the characteristics of OMI were analyzed morphologically and molecularly. The most relevant bands identified were the amide A, B, Ⅰ and Ⅱ, showing crucial spectral differences between apparent normal region and OMI region, including the peak position blue shift and the increased intensity of OMI, moreover relative increase in α-helix and decrease in β-sheet of protein secondary structures in OMI. Comparing to single spectral band, the I1650/I1550 ratio was increased and rationally used as a molecular marker for diagnosing OMI. These novel preliminary findings supported further exploration of FTIR molecular profiling in clinical or forensic study, and were in accordance with histopathology.

Forensic Significance of Messenger RNA and Protein Expression of Genes Downstream of Hypoxia Inducible Factor 2 in Myocardial Tissue for Death Discrimination

Background: As a heterodimeric transcription factor, hypoxia-inducible factor 2 alpha subunit (HIF2A), is an important member of the HIF family. It plays a significant role in the hypoxia adaptation process by regulating the different types of downstream transcription factors and auxiliary regulatory factors. HIF2A-related factors are believed to participate in the progression of myocardial injury or myocardial ischemia, support the protection of ischemic myocardium, and provide guiding significance for the diagnosis and discrimination of sudden cardiac death in forensic pathology. Aim and Objectives: This study aimed to explore the discriminability and applicability of HIF2A-related factors in myocardial infarction cases compared with other causes of death, provide further insights for the forensic diagnosis of heart failure (HF) cases with myocardial infarction, and support the clinical treatment of patients with HF after myocardial infarction. Materials and Methods: The relative expression levels of HIF2A, amphiregulin (AREG), potassium large conductance calcium-activated channel subfamily M β1 (KCNMB1), peroxisome proliferator-activated receptor α (PPARA), vascular endothelial growth factor (VEGF), and VEGFR2 messenger RNAs (mRNAs) in myocardial tissue samples were performed using quantitative reverse transcriptase-polymerase chain reaction. A partial least squares-discriminant analysis model was constructed to select the indicators with better identification effects for myocardial infarction cases. The protein levels of HIF2A, AREG, KCNMB1, and PPARA were further detected by immunohistochemistry. The forensic autopsy cases (27 cases in total, postmortem interval <72 h) included seven cases of acute myocardial infarction and ten cases of myocardial ischemia. There were ten cases in the control group, including four cases of traffic injury, one case of injury by fall from height, and five cases of blunt force injury. Results: Characteristic results were observed in the myocardial ischemia/infarction samples. Compared with the control group, the relative mRNA expression levels of AREG, KCNMB1, and PPARA were significantly increased during the progression of myocardial ischemia, but this was not observed for HIF2A, VEGF, or VEGFR2 mRNA. Immunohistochemistry assays further verified the expression levels of the related factors at the protein level, and H and E staining showed signs of angiogenesis and inflammation in the ischemia/infarction group. Conclusions: By controlling the expression of downstream target genes (AREG, KCNMB1, and PPARA) during myocardial cell hypoxia adaptation, HIF2A has a potential significance in the diagnosis of myocardial infarction in forensic medicine. We believe that HIF2A, AREG, KCNMB1, and PPARA can be used as molecular pathological biomarkers for the discrimination of causes of death in myocardial infarction cases.

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.

Identification of Half‑Sisters from Different Mothers by Autosomal and X Chromosomal Short Tandem Repeats:A Case Study

Complex kinship identification such as half‑sibling identification is a difficult task in forensic biology Here we represented an approach in dealing with half‑sisters from different mothers,with the combination of autosomal and X chromosomal short‑tandem repeats(STRs)data.X chromosomal STRs can offer additional information,especially in some cases where autosomal STRs alone may not provide enough information for an accurate opinion.In this case,half‑sister or unrelated relationship between two women(S_(1)and S_(2))with different mothers were distinguished.23 autosomal and 31 X chromosomal STRs of S_(1),S_(2),S_(1)’s mother(M1),S_(2)’s mother(M2)and S_(1)’s grandmother(G1)were profiled with three different commercial kits.As to X‑chromosome STRs,likelihood ratios(LRs)were calculated by FamLinkX with consideration of linkage,linkage disequilibrium,and mutations.When only the profiles of the two individuals(S_(1)and S_(2))were available,LRs between S_(1)and S_(2)were 1.1110×10^(2)based on 23 autosomal STRs and 3.2257 om107 based on 31 X chromosomal STRs.When the maternal genotypes were taken into consideration,LRs increased to 2.5297×10^(3)and 3.0563×10^(18).Therefore,both the DNA profiles of each mothers and X chromosomal STRs are important in dealing with the identification of half‑sisters from different mothers.

Study of Autosomal Short Tandem Repeat Loci Using ITO Method in Full‑Sibling Identification

This study aimed to investigate the application of autosomal short tandem repeat(STR)loci using the ITO method and discriminant function algorithm for full‑sibling(FS)identification.A total of 342 pairs of full siblings(FSs)and 3900 pairs of unrelated individuals(UIs)were genotyped at 51 STR loci.The groups were in accordance with discrimination power(DP)values and the number of loci,and the values of FS index(FSI)of FSs and UIs were calculated by the ITO method.The discriminant functions of FS–UI were established using the Fisher’s discriminant analysis method with SPSS 19.0 software.All the lgFSI values in the FS and UI groups followed a normal distribution,and there were significant differences between the two pairs.A higher average DP value was associated with a more significant difference,as was a greater number of STR loci detected.Receiver operator characteristic curves showed that the accuracy of FS identification can be affected by both locus polymorphism and the number of loci detected.Comparing the rate of false positives and false negatives of discriminant function between the two groups,a higher average DP value and larger number of loci detected were associated with a lower rate of miscarriage of justice and were more helpful for FS–UI identification.The ITO‑based discriminant analysis method has high applicability in FS–UI tests.Testing of a greater number of STR loci promotes FS identification.

Degradation ofβ‑Actin mRNA and 18S rRNA in Mouse Spleen Cells after Death

We observed degradation ofβ‑actin mRNA and 18S rRNA in mouse spleen cells under constant temperature conditions in the different temperature group during postmortem intervals(PMIs)of 0-72 h.Thirty‑nine mice were sacrificed by cervical dislocation and kept at constant temperatures of 10℃,15℃,20℃,25℃,and 30℃.From 0 to 72 h after death,total RNA in spleen cells was extracted every 6 h.The cycle threshold(Ct)values ofβ‑actin mRNA and 18S rRNA were obtained by real‑time‑quantitative polymerase chain reaction.The results showed that,under the conditions of different and constant temperatures after mouse death at 72 h,the Ct values ofβ‑actin and 18S,Ct ratios ofβ‑actin to 18S,and relative ratios ofβ‑actin to 18S were significantly correlated with PMI.In addition,the relative degradation rates ofβ‑actin and 18S appeared to change from fast to slow with the increase of temperature.By interpolation and fitting analysis of the data,we obtained a ternary quintic equation of the relationship between the change in the relative ratios and PMI,which can be used to infer PMI within a certain temperature range(10℃-30℃).

Research on Several Inspection Methods to Determine the Sequence of Photocopying and Stamping

Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depends on the relationship between the generation time of the document?s content and its stamping.Usually,a formal(legal)document would become effective once a seal is affixed,and normally,the content of the document is generated first and then subsequently stamped after being approved by the relevant personnel.Therefore,correctly identifying the sequence used to produce a document is necessary to detennine whether it is authentic or whether it may have been forged.However,because of the interference of many factors,the identification of such kind of forged documents has long been considered one of the most difficult technical issues in the field of questioned document identification.In this work,four nondestructive approaches to determine the order of photocopying and stamping were investigated:The stereomicroscope method,fluorescence microscopy,the three-dimensional pseudo-color method,and the contour ring method.Each method is associated with its own advantages and disadvantages,but all have been shown to produce some useful results relevant for determining the sequence of photocopying and stamping.

Fundamental Frequency Statistics for Young Male Speakers of Mandarin

In forensic speaker comparison(FSC),it is essential not only to evaluate the similarity between two(or more)samples,but also the typicality of the features in the relevant population.For the typicality,it is necessary that the population statistics related to the phonetic parameters be available.This article presents the statistics for the fundamental frequency(F0)of 100 young Chinese male speakers producing both reading and spontaneous speech.Five descriptive statistics of long‑term F0,namely mean,median,mode,standard deviation(SD),and coefficient of variation(CV=SD/mean),are shown in histograms and scatter diagrams.Results show that the distributions of the five statistics are near normal.The findings are compared with the literature and discussed with respect to forensic phonetic implications.This article concludes that the results for the F0 statistics in the present study can be used in FSC casework as reference data on F0 for the young male Chinese population.

Importance and Guidelines of Postmortem Examination on COVID-19 Cases:An Overview

Since the outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)occurred in December 2019,in Wuhan,China,the COVID-19 has spread to 216 countries,areas,and territories and killed more than 400,000 people worldwide.On March 11,the World Health Organization(WHO)declared COVID-19 a pandemic.The pathological findings of COVID-19 by postmortem biopsy were first reported in April 2020.Since then,there have been many publications regarding the postmortem pathological findings of different organs of COVED-19 patients.Well-performed systemic autopsy examination on patients with related diseases,acute respiratory distress syndrome coronavirus(SARS-CoV),and Middle East respiratory syndrome coronavirus has provided critical infomiation for better understanding the pathogenesis of the emerging infectious diseases in the past Au overview on the importance and guidelines of postmortem examination on suspected or confirmed COVID-19 patients is presented.

Genetic Diversities of 23 Y‑Chromosome Short Tandem Repeat Loci in a Han Population in the Beijing Region

We investigated the polymorphisms of 23 Y‑short tandem repeat(STR)loci in a Han population in the Beijing region.Blood samples were collected from 255 unrelated Han males.DNA templates were amplified using the PowerPlex®Y23 system,and the amplification products were detected with a 3130 genetic analyzer.A total of 254 haplotypes were detected from the 255 unrelated Han males in the Beijing region.The gene diversity of these 23 Y‑STR loci was 0.3952–0.9721.The haplotype diversity was 0.99996 and discrimination capacity(DC)was more than 99.6%.The 23 Y‑STR loci used in this study are highly polymorphic in Han individuals in the Beijing region and are therefore suitable for paternal kinship identification.Studying allelic deletions such as DYS448 and DYS549 are important for examining Y‑STR polymorphisms and forensic testing.

Suicide Deaths in China:An Analysis of Forensic Cases

Suicide cases are often encountered during death investigations in forensic medicine.In this study,through a comparative analysis of our own data of 98 suicide cases and previous reports from various forensic institutions in China,we analyzed the risk factors of Chinese suicides and explored the implications thereof from a forensic point of view.Moreover,the age and sex differences,means,causes,and other concerns regarding suicide are discussed along with a review of the literature.

Image Analysis on Corneal Opacity:A Novel Method to Estimate Postmortem Interval in Rabbits

Corneal opacity is one of the most commonly used parameters for estimating postmortem interval （PMI）. This paper proposes a new method to study the relationship between changes of corneal opacity and PMI by processing and analyzing cornea images. Corneal regions were extracted from images of rabbits＇ eyes and described by color-based and texture-based features, which could represent the changes of cornea at different PMI. A KNN classifier was used to reveal the association of image features and PMI. The result of the classification showed that the new method was reliable and effective.

Quantitative Analysis of Kruppel‑Like Factor 5‑Related Messenger RNA Transcripts in Ischemic Myocardium for Discrimination of Death Causes

Background:Accumulated studies have demonstrated that Kruppel‑like factor 5(KLF5),a transcription factor,plays an important role in regulating cell proliferation and tissue remodeling through the expression of its downstream genes.KLF5‑related factors are expected to be involved in the healing process after myocardial injury or myocardial ischemic changes,especially for the forensic diagnosis of myocardial ischemic physiopathology.Aim and Objectives:This study aimed to explore the discrimination ability and applicability of KLF5-related factors in SCD caused by MI compared with other causes of death to provide further insights into the forensic diagnosis of myocardial ischemic pathology.Materials and Methods:The relative quantification of F‑Box and WD Repeat Domain Containing 7(FBW7),KLF5,factor‑binding protein(FGFBP)1,and FGFBP2 messenger RNAs(mRNAs)in myocardial tissue samples was performed using real‑time fluorescence quantitative reverse transcription polymerase chain reaction.KLF5 and FGFBP1/2 protein levels were examined using immunohistochemistry(IHC).The forensic autopsy cases(27 in total,autopsy within 72 h postmortem)included seven cases of acute myocardial infarction and 10 cases of acute myocardial ischemia.There were 10 cases in the control group,including four cases of traffic injury one case of injury by fall from height,one case of electric death,and four cases of blunt force injury.Results:Characteristic results were found in myocardial samples from three groups of deaths:KLF5 and FGFBP1 mRNA levels were significantly elevated in the infarction and ischemia groups,while FBW7 mRNA levels were significantly decreased.FBW7 is an important ubiquitin ligase that can mediate the degradation of KLF5 protein.In addition,FBW7 and FGFBP2 mRNA levels were decreased in the infarction group compared with the ischemia group.The IHC results were consistent with the observed mRNA expression patterns.Conclusions:Quantitative detection of FBW7,KLF5,FGFBP1,and FGFBP2 mRNA transcripts in myocardial tissues supports the pathophysiological study of myocardial ischemic diseases and provides molecular pathological evidence for forensic discrimination of death causes.

Forensic Examination of Abusive Head Trauma in Child Abuse Cases

Abusive head trauma(AHT)in child abuse cases is rarely encountered in the practice of forensic examination in China,and such cases are rarely reported.The authors reviewed a large number of relevant domestic and foreign studies to differentiate between the definitions of AHT and shaken baby syndrome;determine the relationship between the two;and discuss their epidemiology,mechanism,and symptoms.In addition,the main points in forensic examination and strategies for preventing AHT are also summarized to help forensic workers and clinicians identify and prevent such injuries.

Forensic Investigation of Atypical Asphysia

Smothering,choking,confined spaces,traumatic asphyxia,positional asphyxia,and other kinds of atypical mechanical asphyxia are not rare in forensic practice.However,these are not commonly well demonstrated in forensic monographs worldwide.The authors researched related works and literatures and summarized these with a view to contribute to the existing teaching resources and provide help to forensic practitioners who are involved in scene investigation and identification of such deaths.

A general powder dusting method for latent fingerprint development based on AIEgens

Powder dusting method is the most practically useful approach for latent fingerprint development in the crime scene. Herein, a general powder dusting method has been explored for latent fingerprint development based on aggregation-induced emission luminogens(AIEgens). A series of tetraphenylethene(TPE) derivatives with multiple diphenylamine(DPA), namely, TPE-DPA,TPE-2 DPA and TPE-4 DPA, were selected as candidates to dope with magnetic powders and applied for latent fingerprint development. After screening, the magnetic powder 3 doped with TPE-4 DPA proves to be the best, in terms of fluorescent intensity, resolution and adhesiveness. Afterwards, the magnetic powder 3 was applied for visualization of latent fingerprint on various smooth and porous substrates, including glass, stainless steel, leaf, ceram, plastic bag, lime wall, wood and paper money.Specific details, such as island, core, termination and bifurcation, can be clearly observed for the fluorescent fingerprint images.

尸检样本乙醇分析结果的解释策略

由于死后各种复杂的人为现象的存在,使得建立死后血液酒精含量(BAC)和死亡时醉酒状态之间的关系十分困难。在日常检案中必须考虑细菌污染、发酵是否引起死后乙醇再合成,死亡时胃中未被吸收的乙醇是否向周围组织以及血中扩散等问题。本文总结了关于死后乙醇分析及结果解释相关问题的研究文献,旨在为从事法医毒物学乙醇分析的同行在调查此类案件时提供良好的开端。

Sudden Cardiac Death in Forensic Medicine

Sudden cardiac death(SCD)is a major public health problem and a devastating event for the family and for the community as well.It is estimated that approximately 544,000 SCDs each year in China.^([1])The etiology of SCD has been extensively studied.^([2,3])Ischemic heart disease is responsible for up to 70%of SCDs,whereas other structural heart diseases and primary arrhythmia account for the majority of the remaining SCDs.Postmortem diagnosis of SCD has been challenging for forensic pathologists,and SCD is a hot field of forensic research.^([4])