Objective To evaluate the sensitivity,repeatability,anti-degradation ability,in vivo temporal stability,and tissue specificity of the DNA methylation sequencing panel constructed in our previous study for height inference,so as to provide a reference for forensic application.Methods Sensitivity:different initial template quantities(50 ng,40 ng,30 ng,20 ng)were set for sequencing.Repeatability:DNA from the same sample was sequenced three times.Anti-degradation ability:whole blood was used to make blood stains,and DNA was extracted and sequenced at 0,3,6 and 9 months,respectively.In vivo temporal stability:the blood was collected at 0,3,6,and 9 months for sequencing.Tissue specificities:published data and findings were used to analyze the tissue specificities of CpGs in the panel.Results The sensitivity test showed that the initial template quantities of 20 ng detected all the CpG sites and still obtained accurate prediction results.The results of the three repeated predictions of the same sample are stable,and the differences are mainly due to the randomness of the DNN model,indicating good detection repeatability.A complete methylation profile was obtained for the blood stains left at room temperature for 9 months,and the predicted results showed a small range of fluctuations.The three samples were predicted to fluctuate within a range of 1.5 cm or less over nine months.Tissue-specific analyses showed a high correlation between blood and saliva,but can not apply to other tissues.Conclusion The DNA methylation detection system we developed in our previous study has good sensitivity,repeatability,anti degradation ability,in vivo time stability,as well as strong tissue specificity,making it suitable for height inference of blood samples.This supports the feasibility of using targeted DNA methylation analysis on whole blood samples to infer height in the field of forensic science.

Objective To investigate the value of MRI of the sternal end of clavicle in bone age assessment in Chinese population,especially its applicability in the determination of criminal responsible age.Methods A total of 431 patients aged from 10.00 to 29.99 years with neck or chest MRI were retrospectively collected.According to the Schmeling grading method,the epiphyseal development of the clavicle MRI was divided into five grades.The consistency of methods was evaluated.The correlation and general descriptive analysis between MRI grades and age was analyzed.The sex difference was analyzed.Curve fitting was used to establish a nonlinear model between age and grades.Results The grades of clavicle MRI showed a significant age-related trend(Figure 2),and the correlation was 0.861(0.887 in males and 0.840 in females).Except for grade 1,there was no significant difference between males and females in other grades.The minimum age of male grade 3 was greater than 14 years old,and the minimum age of female grade 3 was greater than 16 years old.The minimum age in grade 4 and grade 5 was over 18 years old in both sexes.The best curve fitting model was cubic model for both sexes(R2=0.805 for men and 0.722 for women).Conclusion Clavicle MRI can be used for the assessment of bone age in Chinese population.Complete epiphyseal plate closure can be used as a reliable indicator for the determination of age at 18 years old,and it is expected to achieve radiation-free forensic bone age assessment.

Objective To detect diatoms in tissues and water samples from drowning cases by gene array,and explore the application value of DNA microarray.Methods Diatoms in the lung,liver,kidney samples,and on-site water samples from 19 drowned corpses that appeared in the rivers of Zhongshan City between July 2021 and April 2022,were detected by gene arrays.Moreover,diatom detection was also performed on 28 samples from 7 corpses by microscope.Then the testing results were compared and analyzed.Results For those 28 samples,diatom types in both tissue and water samples by gene detection were more than those detected by microscopy,the detection was statistically significant(P<0.05).However,there was no statistically significant difference(P>0.05)in the detection of diatom types between tissue samples and water samples both using gene arrays.In terms of tissue samples,diatoms were easier to be detected in lung than liver or kidney,and there were also more types of diatoms detected in lung.Diatom detection by gene arrays showed that the diatom types showed a decreasing trend as the tissue was further away from the entrance of body,and the difference of diatom types increased among tissues.Conclusion The gene array can effectively detect the diatom types and distribution characteristics in drowned corpses,and has great potential in the research of the traceability analysis of corpses found in water and the causes of death.

Objective To establish a 103-plex InDel-SNP composite marker amplification system based on Ion Torrent PGM/S5 sequencing platform targeting fragment length less than 175bp,providing an efficient analytical tool for forensic individual identification and paternity identification.Methods Using the human genome GRCh38 as the reference sequence,InDel-SNP composite marker loci suitable for Chinese population were screened from 22 pairs of autosomes and sex chromosomes by using dbSNP database with East Asian population as the target population.Population genetic data of 267 unrelated individuals of Han nationality in Shandong province were investigated,and genetic relationship was verified using 16 real triplet families.Results The 103-plex InDel-SNP composite marker detection system developed in this study,based on the second-generation sequencing platform,exhibits notable features including high sensitivity,excellent stability,strong specificity,and wide applicability to conventional test materials.It effectively enables the determination of typing results for degraded and mixed samples.Conclusion All 16 parent triplet pairs demonstrated adherence to Mendelian inheritance law without any observed allelic dropout or mutation.This detection system holds significant value for forensic individual identification and paternity testing.

Errors in forensic medical examination have been reported both domestically and internationally,leading to criminal wrongful convictions.As the ancients said,"No one is a saint without faults".No one is perfect,and people will make mistakes.Errors in forensic medical examination are an objective phenomenon,and we should have a correct understanding of them.There are many reasons that can cause errors in forensic medical examination,including the eligibility,competence and cognitive bias of forensic medical examiner.Errors in forensic medical examination are subjective,multidimensional,and relative.The evaluation criteria for errors in forensic medical examination should be based on three aspects:errors related to human behavior,errors caused by technical errors involving instruments,and errors related to more fundamental methodological factors inherent in the relevant field.A quality management system for forensic medical examination should be established,and a fault-tolerant mechanism for actively detecting,reporting,and correcting errors should be established.Training for forensic medical examiners should be strengthened,and a forensic communication mechanism between forensic medical examiner and relevant parties should be established to minimize the occurrence of errors in forensic medical examination.

Through a comprehensive analysis of four cases involving repeated forensic clinical identification on the degree of human injury,disability grade,causal relationship of injury and disease,medical damage liability dispute,the reasons for the emergence of different appraisal opinions are explored.According to the reasons for the disputed conclusion,the deviation or error of the appraisal opinion can be classified in a variety of ways.Among them,the inherent limitations of theories and methods used as appraisal bases,the lack of operational skills or cognitive ability of appraisers,the unclear provisions of appraisal standards and the lack of adequacy and validity in the process of analysis and reasoning are the key reasons for the deviation or error of appraisal opinions.In light of these findings,it is necessary to strengthen the review of expert opinions in judicial practice and form a powerful error correction mechanism.

There are quality deficiencies,disagreements,and even errors in forensic medical examination and identification,especially in fields that rely mainly on professional judgment,where subjective factors heighten vulnerability to,quality issues.In this situation,the most effective way to reduce quality defects and errors is to construct and apply systematic targeted quality control methods reasonably.This study focuses on the field of forensic medical examination and identification,which is mainly based on professional judgment.By summarizing the quality control methods provided in international standards and the existing experience and research results in the field of forensic science,it provides quality control methods for personnel competency,cognitive bias,standardized documentation,and expression of opinions.It also discusses key considerations for carrying out quality control activities,providing reference for preventing quality problems and opinion errors in forensic medical examination and dentification activities.

Objective To investigate a rapid detection method for compressed Nitrous oxide(N2O).Methods The GC-MS system was employed under conventional chromatographic conditions(without replacing standard columns or utilizing headspace sampling)by directly injecting a small gas sample for analysis.N2O identification was performed via NIST spectral library matching,while qualitative and quantitative purity assessments were achieved by monitoring the relative abundance variation of the characteristic fragment ion m/z 30 to eliminate CO2 interference.Results The fragment ion m/z 30 demonstrated specificity for N2O identification.A linear correlation was observed between the peak area of m/z 30 and N2O purity(y=22.741x-1.4565,R2=0.912 6),enabling quantitative purity determination.Additionally,the abundance of m/z30 exhibited a correlation with N2O in CO2 mixtures(y=0.7787x-0.0387,R2=0.722 2).Conclusion Conventional N2O identification typically requires dedicated GC-MS systems,gas-specific chromatographic columns,and headspace sampling.This study successfully utilized routine chromatographic conditions for organic toxicant screening to achieve rapid N2O analysis.The proposed method holds practical significance for compressed N2O identification in forensic and analytical applications.

Objective To establish a purification,enrichment and test method of tetrodotoxin in blood.Methods Through the investigation of various hydrophilic chromatographic columns,the comparison of extraction effects of different types of solid phase extraction columns and the interference analysis of mixed peaks on qualitative ion pairs,the matrix influence of tetrodotoxin was reduced,and the detection sensitivity and qualitative accuracy were improved.Results Tetrodotoxin is highly polar and easily inhibited by the matrix,while conventional precipitation protein method has low sensitivity and isomer double peaks,and the C18 column is not reserved.After comprehensive comparative analysis,the weak cation exchange column PWC column is finally used for purification and enrichment.Complete elution was achieved using 0.5 mL 10%formic acid and 50%acetonitrile aqueous solution.Seperation was performed on an Atlantis HILIC column,with qualitative ion pairs set at m/z,320.10>162.15 and 284.15.The detection limit of the method was 0.061 ng/mL.Conclusion The established PWC solid-phase extraction-LC/MS detection method demonstrates significant purification efficacy,minimal matrix influence,unobstructed chromatographic peaks,markedly improved detection sensitivity.This approach is operationally simple,and applicable to forensic casework.

Objective To develop a method of pulsed direct current electrospray ionization mass spectrometry(pulsed-dc-ESI-MS)for rapid detection of 4 kinds of amphetamines in saliva.Methods Saliva samples were adjusted to optimal pH using NaOH,followed by protein precipitation with anhydrous magnesium sulfate and liquid-liquid extraction with ethyl acetate.The supernatant was then analyzed via pulsed-dc-ESI-MS.Results The limits of detection were 0.01～0.5 ng/mL and the limits of quantitative were 1.0～5.0 ng/mL.In addition,in the concentration range,4 amphetamines have good linear relationships,the correlation coefficients(R2)were all greater than 0.999,the recoveries of 97.21%～104.70%and the relative standard deviations(RSDs)were less than 10%.Conclusion The method has the advantages of simple operation,fast detection,high sensitivity,selectivity and good stability.It can be used for on-site rapid detection of amphetamines in saliva.