A method was developed for the determination of etomidate and its metabolite etomidate acid in hair and urine by high performance liquid chromatography-triple quadrupole tandem mass spectrometer (HPLC-MS/MS). The hair samples were ground and extracted by ultrasonic extraction with methanol. After protein was precipitated by acetonitrile, the urine samples were centrifuged at high speed and passed through 0.22 μm filter membrane, and then Agilent Eclipse Plus C18 RRHD (3.0 mm×150 mm×1.8 μm) column was used for analysis. Gradient elution was performed with 0.1% formic acid aqueous solution-acetonitrile as mobile phase at the flow rate of 0.5 mL/min. Electrospray ion source and multiple reaction monitoring (MRM) positive ion mode were selected. The results showed that the linear relationship of the two compounds exhibited good linearity in the concentration range of 0.5 to 50 ng/mL in urine and 0.025 to 2.5 ng/mg in hair, and the R² value was greater than 0.992 5. The extraction recoveries ranged from 91.0% to 107.5%, and the intra-day and inter-day precision RSD was 0.4% to 7.4%, while the intra-day and inter-day accuracy was 91.5% to 110.8%. In the actual cases, six hair samples and 4 urine samples were tested, and the test results showed that etomidate was detected in all six hair samples, and the metabolite etomidate acid was detected in two hair samples, but the concentration was much lower than the original. Etomidate and metabolite etomidate acid were detected in two urine samples, and the metabolite concentration was much higher than the original. In conclusion, this method can be used for rapid qualitative and quantitative analysis of etomidate and its metabolite in the hair and urine of etomidate users.

In this article, the Raman spectrum inspection performance of six drug seizures at three different excitation wavelengths (532, 785, and 1 064 nm) is compared using Raman spectroscopy. Three to five distinctive scattering peaks in the Raman fingerprint area (100-1 800 cm^-1), with greater scattering intensity and no interference from typical adulterants, were chosen as the bass for the qualitative matching of the drug seizures when compared to the Raman spectra of the drug standards. It was discovered that in order to perform a Raman investigation of drug seizures, appropriate excitation wavelengths must be chosen based on the kind of drug involved. Additionally, if the drug seizures contain adulterated substances, the distinctive peaks of the pharmaceuticals that escape adulteration should be chosen for comparison. For seized heroin (HER), caffeine (CAF) and 3,4-methylenedioxymethamphetamine (MDMA), the near-infrared (NIR) excitation wavelengths of 785 nm and 1 064 nm are better than that of 532 nm for the Raman test, in which the 1 064 nm significantly reduces the background fluorescence of the HER seizure; for seized methamphetamine (MAMP) and ketamine (KET), the effect of the change of excitation wavelength was small, and the Raman response was good at three different excitation wavelengths, and the relative intensities of the Raman peaks in the fingerprint region and the functional group region (2 500 to 3 200 cm^-1) showed regular changes; for the Raman analysis of Magu, the excitation wavelength of 785 nm was superior, with a higher spatial resolution, which could observe more characteristic peak information while avoiding the fluorescence effect. This research work is based on Raman spectroscopy, which will provide a strong reference and basis for drug enforcement.

The aim of this study is to provide guidance and reference for further research in related fields by analyzing in-depth the current research status, emerging themes and future development trend of forensic entomology. In order to achieve this goal, the authors systematically searched the literature related to forensic entomology from CNKI (China National Knowledge Infrastructure), Wanfang database, and Pubmed database during the period from 2003 to 2023. Using CiteSpace 6.2.R4 Advanced software, the authors visualized and analyzed these literatures in terms of annual publication trends, authors, countries, institutions, and keywords. After rigorous screening, a total of 499 domestic and 2 137 foreign literatures, totaling 2 636 articles, were included in this study. The analysis results showed that although China has made some progress in the field of forensic entomology, there is still much room for improvement in international cooperation and exchange. Meanwhile, the inference of the time of death (PMI) of corpses is a research hotspot of common concern at home and abroad, but there are differences in research focus among countries. We conclude that China must strengthen empirical research and field investigation, focus on the combination of theory and practice, improve the application value and influence of research, and enhance communication and cooperation between scholars internationally to jointly promote the development of forensic entomology.

From Sanger sequencing to high-throughput sequencing, the rapid development of sequencing technology has been providing better technical support for combating crime through forensic DNA analysis. In recent years, the third-generation sequencing technology, mainly based on nanopore sequencing technology, has been widely applied in life science research, in vitro diagnosis, public health, food safety and other fields. Nanopore sequencing technology with super-long reading and real-time sequencing has great potential in the field of forensic genetics. Many authorities and experts have already realized the great potential of nanopore sequencing applications for forensic purposes, although its application in forensic science is still in its infancy. There is little relevant research literature in the field of forensic science, and we should research and explore it further. In this article, the authors attempt to describe the basic principle and characteristics of nanopore sequencing technology, and share the updates of nanopore sequencing-based STR typing, MH typing, mtDNA, DNA methylation and RNA sequencing during the past several years. Meanwhile, non-human genetic material can provide medical examiners with special evidence and clues. The past decade has witnessed the enormous potential of nanopore sequencing technology in non-human forensic genetics. Especially in the areas of microorganisms, plant, and animal forensics, the application of nanopore sequencing to species identification can exert a huge implication, and provide the vital evidence and clues for the public security. In addition, nanopore sequencing has been used to detect viruses at the scene. In the field of forensic genetics, the nanopore sequencing with portability and real-time sequencing makes it most likely to sequence directly of biological samples at the crime scene. This development of the nanopore sequencing has opened up new possibilities by bringing “the laboratory into the field”. This draw the incomparable attraction to the practical application in public security. Moreover, several problems with nanopore sequencing in forensic genetics are discussed, including complex data analysis, high error rate, high sample quality requirements, and analytical methods, and there is a certain distance from the daily application of forensic genetics, which need in-depth research. Finally, we hope that this review can provide a reference for related research and applications, opening up ideas for relevant personnel.

The synthesis of three β-substituted ninhydrin derivatives and their application to the development of latent fingerprints on paper surfaces were investigated. Under the same concentration, the effects of β-OMe, β-NO₂, β-Me ninhydrin were compared through latent fingerprint developments on different papers with multiple dimensions, respectively, and their effects were also compared with ninhydrin to analyze the advantages and disadvantages. Three β-substituted ninhydrin derivatives could develop fingerprints on different papers. The effect of β-NO₂ ninhydrin was slightly inferior to the others as its solution was brown at the same time the displayed fingerprint was dark brown; the effect of β-OMe, β-Me ninhydrin was equivalent to ninhydrin in many dimensions and the sensitivity was slightly higher than ninhydrin, as well as the stability of Ruhemann’s purple. The modification on β-position could change the fingerprint development effect of ninhydrin; the substitution of electron-donating groups could improve the fingerprint development effect of ninhydrin; the fluorescence performance of these compounds was not directly related to the visual effect of fingerprint display.

In the process of investigating telecommunication network fraud cases, especially in cases such as click farming, investment and financial management fraud and naked chat, APP and URL forensics analysis are the focus of network-side investigation. Because of the need to realize functions such as chatting, picture uploading and voice calling in the APP involved, the APP developed based on IM framework has become the mainstream, among which NetEase Yunxin IM is the most common third-party IM framework in the current fraud cases. However, as criminals continue to hide their means of committing crimes, for example, encrypting APPs or encrypting chat content end-to-end, direct analysis cannot obtain the key value of IM interface, or only the encrypted garbled code can be obtained, and chat content cannot be viewed. Based on this kind of cases, this paper introduces the principle of IM framework, the encryption technology and decryption method of APPs and chat content. Through in-depth reverse analysis and encryption algorithm analysis of this kind of APPs, the efficiency of clue mining and investigation and evidence collection of single fraud cases can be fully improved, which provides strong support for the detection of related cases.

In this paper, the specific structures of two first-phase metabolites of 2-fluoro-deschloroketamine except nor-2-fluoro-deschloroketamine were determined, and a detection method of 2-fluoro-deschloroketamine, nor-2-fluoro- deschloroketamine, cis-Dihydro-2-fluoro-deschloroketamine and trans-Dihydro-2-fluoro-deschloroketamine in urine was estabished using HPLC-QQQ MS/MS. Through HPLC-HRMS screening, two metabolites of 2-fluoro-deschloroketamine, namely cis-Dihydro-2- fluoro-deschloroketamine and trans-Dihydro-2-fluoro-deschloroketamine were determined and then were synthesized specifically. The structures were identified by ¹H NMR, ¹³C NMR and 2D NOE NMR. The HPLC-QQQ MS/MS method for the detection of 2-fluoro-deschloroketamine, nor-2-fluoro-deschloroketamine, cis-Dihydro-2-fluoro- deschloroketamine and trans-Dihydro-2-fluoro-deschloroketamine in urine was established, which possesses a good linear relationship for 2-fluoro-deschloroketamine and its three main metabolites at the concentration range of 0.5~200 ng/mL, with the linear correlation coefficients all greater than 0.996 3, and the recoveries ranging from 81.60% to 119.33%. The quantitation of 2-fluoro-deschloroketamine and its three metabolites in actual urine samples was detected by the established method. This study determined the specific structures of two first-phase metabolites of 2-fluoro-deschloroketamine. The developed testing method has low detection limit, high recovery, and good reproducibility, which can be used in the qualitative and quantitative detection for the stable metabolites of 2-fluoro-deschloroketamine.

This paper explores the progress of artificial intelligence technology in the identification and reconstruction of crime scene elements. With the development of information technology, there are challenges faced by crime scene element identification and reconstruction. The paper discusses the application benefits of artificial intelligence, the relevant applications of artificial intelligence in forensic examination, and outlines the key steps of artificial intelligence in crime scene element identification and reconstruction, to explore the possibility of applying this method to crime scene element identification and reconstruction. Finally, the paper looks forward to the future development of artificial intelligence in forensic examination and suggests that it may play an important role in improving the intelligence level of crime scene examination and increasing the efficiency of case investigation. It is hoped that relevant research will provide a solution for the technical transformation of crime scene examiners and lay a foundation for the intelligent and digital development of forensic technology.

Objective and accurate forensic genetic analysis results are the basis for making accurate identification opinions. With the increasing sensitivity of testing equipment and amplification kits, the pressure to prevent laboratory pollution is increasing. Among them, the contamination of PCR amplification products is the most difficult type of pollution to prevent. This research introduces an anti-pollution amplification kit, which contains 16 short tandem repeats (STR) locus, one sex identification locus (Amel) and one Y chromosome insertion deletion locus (Indel). Anti-pollution amplification kit can obtain DNA fragment containing uracil base through STR multiplex amplification, and this type of DNA fragment can be efficiently hydrolyzed by uracil DNA glycosylase (UDG enzyme) at 50℃. An additional 50℃ incubation before each new round of PCR amplification can completely eliminate the pollution threat of previous amplification products to the results. After testing, the anti-pollution amplification kit has excellent anti-pollution ability, and uracil base does not change the DNA typing results. Its detection sensitivity does not decrease; the stability of DNA product fragments does not decrease; and subsequent electrophoresis analysis is not affected. This reagent kit can effectively eliminate contamination of amplification products.

Artificial intelligence (AI) is a comprehensive new region developed by computer science, neuroscience, linguistics and other disciplines. It is an intelligent solution based on big data, machine learning and other technologies, which can improve morphological recognition ability, diagnostic efficiency and quality. With the rapid development of science and technology, AI technology has made great progress and been widely used, providing new solutions for solving various practical problems. “AI+” has been widely used in all walks of life and achieved excellent results, among which, a number of excellent research results have emerged in the field of forensic medicine. In recent years, forensic scholars at home and abroad have studied the application of AI technology in many aspects, such as postmortem interval estimation, diatom test, age and sex estimation, DNA map analysis, poison test and injury mechanism determination. The achievements have greatly promoted the progress of forensic science and demonstrated the advantages of applying AI technology to solve traditional forensic problems. This paper summarizes the literatures in recent three years, hoping to provide new ideas for the research of forensic pathology, clinic, anthropology and toxicology.

Kinship analysis of grandparents and grandchildren is an important content in the field of forensic identification, which includes three subtypes: double grandparents and biological mother test (DGBM), double grandparents and alleged mother test (DGAM), and double grandparents test (DG). Until now, no systematic formula has been reported in grandparent index (GI) calculation of grandparent identification in the presence of mutation, apart from few simple calculation methods of partial gene combination in DGBM. In this study, we first created a simplified representation model of grandfather and grandmother in 5 subtypes, in the form of a set of genotypes. The general probability formula of mutation of parent genotype into child genotype (P_(DG→Z)) was derived in 12 subtypes. Furthermore, the general formulas of GI under three conditions were derived: GI of double grandparents and biological mother (GI_DGBM), GI of double grandparents and alleged mother (GI_DGAM) and GI of double grandparents (GI_DG). The detailed formulas were further refined according to genotypes of double grandparents, mother and grandchild. In addition, the percentages of mutations of 5 genetic types in the group of unrelated individuals on 30 STR loci of the EX30 kit were calculated. Finally, models of simulated kinship groups and unrelated individual groups were established respectively. The geometric mean (Π) and 95% confidence interval (CI) of CGI, the percentages of cases where CGI<10 000 in kinship groups, and the percentages of cases where CGI>0.000 1 in unrelated individual groups were calculated in the same 30 STR loci. In this study, the novel formulas can be used to calculate all kinds of GI in the presence of mutation under three conditions. The genotype combinations in all mutation cases were reviewed. Among them, the occurrence rate of both paternal and maternal mutation groups was 13.31%, which could not be ignored. In EX30 kit, the formulas can achieve firm conclusions in DGAM cases for both the kinship group and unrelated individual group; in DGBM cases identifications, all cases in the kinship group and 99.89% cases in the unrelated individual group could be correctly identified; and more genetic markers should be added for DG cases. The geometric mean of CGI in kinship groups sorted by value were as following: Π_DGAM>Π_DGOM>Π_DG, and the rule in unrelated individual groups were as following: Π_DGAM<Π_DGOM<Π_DG. The results of this study show that the here-derived GI formulas could be applied to kinship analysis of grandparents and grandchildren in the presence of mutation under three conditions, which is of high application potential.

In this paper, the characteristics of allele typing deletion of Y-STR loci and its correlation with AZF (azoospermia factor) deletion were discussed, which could provide reference for forensic practice. Y-STR kits (Yfiler Platinum, SureID PathFinder Plus) were used to analyze the blood samples of 23 461 male family members. A total of 14 cases with 4 or more Y-STR allele-dropout samples were found. Meanwhile, Sequence-tagged site (STS) was detected with Y chromosome microdeletion detection kit, and the deletion of AZF region of Y chromosome was evaluated according to the deletion STS. The results showed that the proportion of multiple Y-STR typing missing was 0.059 7% (14/23461), with 1 case of short arm and 13 cases of long arm, which were from different families with different types. STS deletion was detected in the AZF region in 13 long arm multiple typing deletion samples, and no abnormality was detected in 1 short arm multiple typing deletion sample. This study suggests that there is a correspondence between multiple STR allele dropouts in the long arm of Y chromosome and microdeletions in AZF region, and the biological basis of sterility exists in these typing individuals.

New synthetic opioids are on the growing list of illicit drugs and pose a serious threat to human health. Some examples of NSOs include AP 237, piperidine, bromomorphine and a variety of 2-benzyl benzimidazole opiates. 2-benzyl benzimidazole opioids, also known as “Nitazenes”, many of which are regulated by the United Nations Commission on Narcotic Drugs, have become internationally prevalent in recent years. Metonitazene is an emerging potent synthetic opioid that first appeared in the recreational drug supply in mid-2020 and began to surge by the end of the decade, raising increasing public health concerns. In this study, we presented a method for the identification of a novel synthetic opioid metonitazene seized for the first time in China by gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography-quadrupole/electrostatic field Orbitrap-MS (UPLC-Q- Exactive Orbitrap-MS). The unknown samples were extracted by methanol, and the supernatants were analyzed by GC-MS and UPLC-Q-Exactive Orbitrap-MS respectively. Isotonitazene was analyzed as a contrast. By GC-MS detection, the main characteristic ion peaks of the mass spectral fragments of unknown component with retention time of 15.167 min were m/z 86.1 (base peak), 58.05, 121.1, 205.05, 236.05 and 248.1. UPLC-Q-Exactive Orbitrap-MS detection showed that the excimer ion peak of unknown component with retention time of 7.35 min was m/z 383.207 7. The main ions of secondary mass spectrum were m/z 310.118 2, 264.125 2, 121.064 9, 100.112 1 and 72.080 8. Due to the lack of reference substance, the target was identified as metonitazene by retrieval of SWGDRUG and Cayman database, comparison of information in reported literatures and analysis of high-resolution mass spectrometry data. The method is simple, rapid and has good application prospect. It can be used in real case detection.

Physical evidence is the lifeline of investigation, and scientific and effective examination and identification of physical evidence can provide crucial support in reconstructing cases or events. In the context of fire scene evidence, the focus revolves around the nature of the fire and the analysis and determination of the fire’s causes. Particularly in the determination of the fire’s causes, identifying the ignition source, the fuel, and the conditions that lead to ignition are the key factors in the final analysis of the fire’s origin. During the investigation of a complex fire incident in a production workshop, difficulties were encountered in identifying the fuel and the ignition conditions. Through the application of simultaneous thermal analysis techniques to analyze the thermal properties of relevant physical evidence, parameters such as the thermal decomposition initiation temperature were determined. Upon identifying the point of origin, the heat of ignition was determined through the melting point temperature, and the material first ignited was identified through the pyrolysis temperature. Even though the pyrolysis temperature differs from the ignition temperature, the majority of combustion occurs in the gaseous phase, and combustible gas forms the basis of the combustion process. For polymeric materials, the generation of combustible gas must occur through pyrolysis, making pyrolysis a prerequisite for ignition. Only when the combustible material undergoes pyrolysis and produces a sufficient concentration of combustible gas can combustion potentially occur. Materials were collected from the point of origin in this fire investigation, and using thermal analysis techniques, the initial pyrolysis temperature was theoretically used to reasonably infer and identify the material first ignited, offering crucial reference for the analysis and identification of similar fire incidents.

Currently, capillary electrophoresis-based Y-STR genotyping kits can detect up to 40 Y-STR loci simultaneously. However, these kits only report length-based genotypes and are unable to provide STR sequence information. The STRSeqTyperY68 kit, designed for forensic male pedigree differentiation using next-generation sequencing technology, excels at genotyping 67 Y-STR loci plus a sex-determinant locus in a single-tube reaction on the MiSeq FGx sequencing platform. It simultaneously provides both length and sequence polymorphism genetic information, simplifies testing procedures, enhances efficiency, and facilitates precise differentiation of male family lineages. The ITO method is commonly used to calculate the kinship index of two individuals’ biological relationship based on Mendel’s law of genetic segregation. Additionally, it evaluates consanguineous relationships within five degrees of kinship between two individuals. The combination of next-generation sequencing technology and the ITO method can effectively narrow down the range of potential families. This paper documents a rape and murder case that remained unsolved for eight years. By cooperatively utilizing the STRSeqTyperY68 kit and the ITO method, the potential connection between crime scene evidence and reference samples was evaluated. Gradually, the investigative leads were narrowed down, leading to the resolution of the case.

Differences in handwriting composition are crucial for recognizing the existence of alterations in questioned document examination. The ambient ionization mass spectrometry is increasingly being recognized for its utility in detecting ink changes, due to its benefits such as high speed, rich information, minimal destruction of the sample. In this paper, the desorption electrospray ionization mass spectrometry imaging (DESI-MSI), a prominent technique within ambient ionization mass spectrometry, was used to examine the suspicious handwriting to determine whether the document was altered. The authenticity of the number “1”, suspected of being added to change“2”into“12”, was scrutinized. The mass spectra of strokes of ink were obtained, and the suspicious“1”could differentiate from other numbers. Based on the MS data, the questioned part could be visualized through imaging, clearly demonstrating the evidence of tampering. Additionally, chemometrics were applied to cluster the handwriting composition data, aiding in the identification of the alteration fact. Compared with the traditional optical detection and spectroscopic method, DESI-MSI offered a more comprehensive analysis of the handwriting’s material properties, showcasing its potential for practical application. This technique provides an innovative perspective for examining such cases.

To solve the disputes on road rights caused by the invasion of traffic width by different traffic participants in the mixed traffic network, a method for measuring road surface distance in videos based on direct linear transformation theory is proposed. This method uses a one-dimensional direct linear transformation algorithm and relies on three characteristic points in the video that are collinear with the point to be measured to determine the direct linear transformation relationship between the image-side distance and the object-side distance, and then calculate the target distance. The measurement errors of this method are evaluated using the measurement values obtained from on-site scanning by Faro Focus^3D laser 3D scanner. Experimental results demonstrate that this method can effectively measure the road distance in videos, with a measurement accuracy reaching the centimeter level, and it is equally applicable to video images taken from different shooting angles. The application of this method can determine the traffic width of different parties involved in accidents in the mixed traffic network through video images, providing technical support for judicial appraisal and accident handling.

As one of the most commonly used reagents for amino acid detection, ninhydrin has a wide range of applications in forensic science and is a classic and effective method for displaying old fingerprints on permeable objects. However, the traditional ninhydrin display method still needs further improvement in the display effect of latent fingerprints on objects with complex background colors. Based on a review of relevant research results at home and abroad, a brief review was conducted on the composition of fingerprint substances, the mechanism of ninhydrin in fingerprint development, and the improvement of traditional ninhydrin development methods. A detailed review was also provided on the methods for enhancing the development effect since ninhydrin was applied in the field of fingerprint development. The innovation of the traditional ninhydrin solution method for enhancing visualization mainly manifests in three aspects: 1) optimization of ninhydrin solution method reagent formula, such as screening of the best solvent, exploring the optimal concentration, and discussing the influence of pH value on visualization effect; 2) The innovation of ninhydrin display methods, such as solid medium method, ninhydrin vacuum fumigation method, spray display method, etc., mainly solves the problems of carbonization interference and background ink interference in thermosensitive paper; 3) The fingerprint enhancement treatment using ninhydrin, mainly includes metal salt enhancement, rare earth-Ruhmann’s Purple violet coordination compound enhancement, and trypsin enhancement. The metal salt enhancement method and the rare earth-Ruhmann’s Purple coordination compound enhancement method have great research potential in the future development trend of latent fingerprints.

With the rapid development of the Internet of Things and artificial intelligence, people’s dependence on data in their work and life is increasing day by day, making efficient and secure storage of data increasingly important. As an effective solution for organizing multiple disk storage, RAID (redundant array of independent disks) has been widely used in recent years and is also a data storage method that public security organs pay great attention to when extracting data during the process of handling cases. However, in the process of investigation and evidence collection, investigators often need to restore the content and structure of RAID data damaged by suspects, and correctly restructuring RAID disk arrays has become an important prerequisite and necessary link for involved website reconstruction analysis and forensics. This article shared a case of illegal transaction website reconstruction based on RAID recombination, detailed the process of RAID restructuring, explained the simulation restoration method for restoring the original server environment after successful RAID restructuring, and provided the operation process for connecting the website and database in a virtual machine environment, and hopes to provide useful reference for electronic data forensics of similar cases.

Objective and accurate assessment of visual impairment has been one of the challenging tasks in forensic identification. In forensic practice, visual impairments are commonly seen as caused by physical factors, but rarely by chemical factors such as methanol poisoning. Methanol and its metabolites can directly damage eye tissues and cause vascular paralysis and dilatation, damaging the nervous system. Visual impairment can appear after a few hours to 2~3 days of poisoning, manifesting as diplopia, blurred vision, and eyeball swelling and pain, followed by rapid vision loss and even blindness. Ophthalmologic examination reveals dilated and fixed pupils and diminished or absent light reflexes. Funduscopic examination reveals dilated veins, optic nerve papilla congestion, and edema, followed by pallor or optic nerve atrophy. Optic nerve damage rarely returns to normal completely. The mechanism of visual function impairment in methanol poisoning is mainly its metabolite formic acid or format, which is excreted very slowly in vivo and has a selective affinity for the eye’s neural tissues, inhibiting the oxidative phosphorylation process, affecting cellular respiration, and inhibiting ATP synthesis in mitochondria, leading to tissue toxicity and hypoxia and then degenerative changes of the cells, oligodendrocytes and astrocytes swelling myelin sheath loss, optic nerve edema and pressure on the optic nerve in the posterior sieve plate region, thus resulting in toxic optic neuropathy. Toxic optic neuropathy occurs when the optic nerve is compressed in the posterior region of the sieve plate, etc. Optic nerve atrophy often occurs after 1 to 2 months, and irreversible damage to the optic nerve and visual function can occur at a later stage. Two injury degree identification cases of visual impairment after methanol poisoning were reported. The methanol poisoning confirmation, the objective assessment of visual impairment, as well as the causal relationship between methanol poisoning and visual impairment, were discussed and comparatively analyzed, with a view to similar cases to provide a reference clue.

Detecting abnormal behavior is crucial for maintaining public security, especially in densely populated critical areas. Traditional target detection algorithms often struggle to deliver satisfactory results under these conditions due to challenges like dense target distribution, significant scale variation, and complex backgrounds. YOLOv8 is one of the better perforing detection models effect among the object detection models. This study introduces a novel approach to improve detection accuracy by integrating advanced mechanisms into the YOLOv8 backbone network. Firstly, the coordinate attention (CA) mechanism is incorporated into the C2f module of the backbone network. This enhances the network’s focus on targets amidst complex backgrounds by emphasizing relevant features and suppressing noise. Secondly, the swin transformer model is integrated into the YOLOv8 backbone. The swin transformer facilitates greater information interaction across the feature map, effectively utilizing the background information and improving object detection accuracy under complex scenarios. The datasets used in the experiments are described, the evaluation indexes of P, R, AP and mAP are listed, and ablation experiments and comparative experiments are carried out. Experiments demonstrate the feasibility and effectiveness of these improvements. The enhanced network is compared with several mainstream networks, showing a significant improvement in average accuracy, reaching 95.1%. Compared to the basic network YOLOv8, the average precision has been improved by 2.4%, which proves the effectiveness of this method. In summary, the innovative integration of the CA mechanism and Swin Transformer model into the YOLOv8 backbone network addresses key challenges in detecting abnormal behavior in densely populated and complex environments. These enhancements lead to improved detection accuracy, making it a promising approach for public security applications.

With the intensive integration of deep learning and computer vision, a series of advanced technologies such as facial recognition, image (video) generation, and image classification, have made rapid progress. However, deep learning models are considered “black box models” due to their difficulty in explaining internal processes and predicting results, which poses a serious challenge to the interpretability of image evidence in the field of forensic science. Based on this, this review outlines an overview of interpretability issues based on deep learning. Emphasis was placed on the theoretical and methodological research on the interpretability of facial features based on deep learning both domestically and internationally, such as saliency maps method, perturbation-based method, and score/statistics-based method. Their applications in facial recognition and other related fields, especially in the field of forensic science portraits, were summarized. This review proposes the problems of facial feature interpretability methods based on deep learning models, and looks forward to the future development direction of facial feature interpretability based on deep learning.

With the swift progress of artificial intelligence (AI), the field of forensic DNA examination is witnessing a technological transformation. AI has been integrated into multiple facets of forensic DNA analysis, encompassing intelligent DNA expert systems, AI-assisted optimization of examination procedures, innovative AI-assisted DNA statistics and analysis, rapid electrophoresis data analysis powered by AI, complex mixture sample analysis, and big data inference models. These advancements have significantly enhanced the precision and efficiency of forensic DNA testing. However, the integration of AI has also introduced challenges such as data privacy, model interpretability, algorithmic bias, and legal regulation. Addressing these issues necessitates close collaboration among forensic DNA experts, bioinformatics specialists, and AI professionals. Additionally, it requires the establishment of appropriate legal and regulatory frameworks to ensure that AI applications adhere to ethical standards and effectively support judicial fairness. This article provides an in-depth examination of the application of AI in forensic DNA analysis and the challenges it presents. It analyzes specific case studies to illustrate how AI contributes to the automation and intelligence of forensic DNA analysis, while also highlighting potential risks and challenges. The paper aims to offer guidance and references for the application of AI in the forensic DNA field.

Rapid non-destructive testing of the formation time of blood stains at different dilution ratios under common temperature and humidity conditions was developed using UV visible reflectance spectroscopy. Dilute fresh blood with anticoagulant by 2, 4, 8, 16, and 32 times with tap water. Take 20 μL diluted blood and drop it in the center of a white cotton cloth. After drying, use the reflection accessory of a UV visible spectrophotometer (UV-2450 type) to collect the reflection spectrum, and Excel was used to do regression analysis of trough values and formation time of blood stains at different concentrations. As time increased, there was a significant blue shift in the reflected wave troughs of normal and diluted blood stains near 577.0 nm and 540.0 nm. The values of R² of the regression equation were all greater than 0.800 0, and there was a good linear relationship between the trough blue shift and the formation time of blood stain. The average speed of the trough blue shift increased with the increase of dilution ratio. Conclusion: The blue shift in the reflected wave valleys at 577.0 nm and 540.0 nm can serve as a basis for determining the formation time of normal blood stains, and combined with visual observation, it can also serve as a reference for determining the formation time of diluted blood stains.

In recent years, with the continuous improvement of public security conditions, the incidence of homicides has significantly decreased, but the occurrence of unnatural deaths remains high and is showing a growing trend. Death from hanging is one of the common causes of unnatural death cases, the key point is identifying suicide or homicide and the difficulty is to judge the manner of death. Homicide from hanging is uncommon. This article introduces the situation of body damage and scene investigation about a typical case of homicide from hanging yet being pretended of suicidal, analyzes the characteristics of suicide and homicide from hanging, and discusses the key points for handling similar cases to provide reference for judgment of death cause, determination of manner of death, and identification of investigation direction in handling related cases.

Calculation of the degree of lung compression by Mimics software remains the “gold standard”. In the forensic sphere, due to the complexity of the Mimics software, many people do not utilize this method in forensic practice. They may calculate degree of lung compression by visual observation, represent the result of degree of lung compression by some slicer of CT. These factors will lead to inaccuracies of calculated results. The aim of this study is to develop a model for automatic calculation of lung compression degree based on deep learning semantic segmentation technology, and explore the feasibility of deep learning for lung compression measurement by comparing the results of automatic calculations with Mimics software. In this study, 42 cases of the computed tomography (CT) data including pneumothorax diagnosis in DICOM format were collected each cases has about 350 images with a thickness of 1 mm. Among them, 32 cases used for training and 10 cases used for validation. The air-containing regions of 1943 images were manually annotated. An additional five chest CT cases were selected for external testing. The degree of lung compression was calculated by both the deep learning model and Mimics software, and the correlation between the results of the two methods and the calculation errors were analyzed. In the validation set, the average error between the deep learning model calculation results and the manual method was 2.4%, and the model processed an average of 356 per case with an average time of 60.04 s, while the average error in the test set was 4.4%. The aforementioned results lead to the following conclusions: The deep learning model constructed in this study has the potential to be applied in the automated measurement of the lung compression degree due to pneumothorax, which can provide a reference for the calculation of the lung compression degree due to pneumothorax in forensic practice.

Fingerprint, one of the most reliable and valuable evidence in the crime scenes, has long been recognized as a powerful tool for personal identification and worldwide law-enforcing departments to fight against relevant crimes. For many years, in practice, fingerprint analysis has been developed based on the latent fingerprint visualization, primarily. However, most of these fingerprints in crime scenes have been ambiguous, deformed or fragmentary, which contributed to the difficulty in fingerprint analysis. So, recently, some researchers have gradually paid increasing attention on the fingerprint age for fingerprint analysis, though their researches were almost taken placed in the lab. To improve the accuracy and reliability of fingerprint age analysis, and effectively promoting the application of fingerprints age in practice, in this article, according to these researchers’ reports, the morphological characteristics of fingerprints related to the fingerprint age, including two-dimensional (2D) morphological characteristics (e.g. ridge widths and color contrast between ridges and furrows) and three-dimensional (3D) morphological characteristics (e.g. ridge heights), were reviewed, respectively. Furthermore, fingerprint residues which are transferred onto the object surfaces when fingertips touch object surfaces, reveal a wealthy of information, especially fingerprint age. Therefore, the changes of fingerprint residues involving electrical effect, the optical characteristics, as well as the change of compositions such as squareness, wax esters and fatty acids, were also comprehensively summarized in this review. Particularly, the future research directions and prospects were discussed about the methods and the reagents of latent fingerprint development, the equipment and the technologies of fingerprint detection, the composition and the degradation rates of fingerprint residues, and the influencing factors model of age determination of fingerprint.

Body fluid stains are common biological materials at crime scenes. The accurate determination of their tissue sources can help with crime scene reconstruction, case nature determination and trial. The analysis of cell-specific mRNA expression has been proposed as promising method for the identification of body fluids. Conventional strategy of mRNA profiling requires reverse transcription, PCR amplification, and electrophoresis. The one-step RT-PCR detection technology can complete reverse transcription and PCR of mRNA in one reaction, which can reduce experimental time and simplify experimental operations. In this study, we subjected the one-step multiplex reverse transcription PCR strategy to mRNA profiling with the inclusion of 10 tissue specific biomarkers in the F13plex system targeting peripheral blood (HBA, HBB), menstrual blood (MMP7, MMP10), vaginal secretion (HBD1, CYP2B7P), saliva (STATH, HTN3) and semen (PRM2, SEMG1), and 3 housekeeping genes (ACTB, GAPDH and RPL19). We verified the system’s specificity, sensitivity, and ability to detect mixed and aged samples. In terms of specificity, most of the selected genes had good specificity, but there were some cross-reactions that were hard to avoid. In order to ensure the accuracy of identification, we determined that the target body fluid was contained only when the three housekeeping genes and two specific mRNA markers were simultaneously detected. In terms of sensitivity, we found that different types of samples had different sensitivities. For example, when using 10 ng RNA for vaginal secretions and menstrual blood samples, some specific target genes were not detected and could not be correctly determined; for blood samples, even when 0.01 ng RNA was used, the RFU value of the target gene is still above 10 000. However, there are only a small amount of test materials in actual cases; it is difficult to quantify the extracted RNA. For five kinds of body fluids, 2 μL of RNA extracted from a 1 mm2 sample could all detect housekeeping genes and corresponding target genes, and the correct body fluid could be determined (Except 1 vaginal secretion sample). The target genes of the mixed components were detected in all 16 mixed samples, and correct mixed component determinations could be made, proving the system’s good ability to identify mixed samples. Almost all housekeeping genes could be detected in 14 aged samples, but only 7 were correctly identified. Because no specific target genes were detected in the remaining samples, correct determinations could not be made. Consequently, the system needs to be further optimized. For HBD1 and MMP7 with poor specificity, other vaginal secretion and menstrual blood-specific genes will be screened and verified for replacement. The instability of mRNA results in relatively poor test results for aged samples. In practical applications, other genetic markers with better stability should be used to determine the results. In general, lots of studies have been demonstrated the usability of mRNA profiling to the identification of forensic relevant body fluid. According to the comprehensive assessment of the one-step RT-PCR strategy in this study, the one-step profiling assays can be a reliable and economical method for the simplified, accurate, and simultaneous analysis of tissue-specific biomarkers for the discrimination of body fluid origin. It shows good application potential in forensic body fluid identification work.

基于传统毛细管电泳技术的STR检验仅关注长度多态性，不能报告STR等长等位基因间的SNP、InDel等序列差异信息。二代测序技术可以检出更丰富的STR序列多态性，既包括重复区的重复序列和非重复间隔序列信息，也包括侧翼区的序列信息，支撑更精准的比对分析。本文报道一起长达21年未破的入室杀人案，用传统Y-STR检测方法得到了38个Y-STR基因座长度多态性分型。通过二代测序方法，使用STRSeqTyperY68试剂盒检验1份现场物证和8份比对样本，均得到了全部67个Y-STR基因座序列多态性分型，其中DYS448基因座N42“折叠序列”中的一个单碱基变异为案件指明方向，提供了关键的技术支撑。本文进一步探讨了DYS448基因座N42“折叠序列”在不同人群中的序列变异情况，以及STRSeqTyperY68试剂盒中具有“折叠序列”的基因座详细信息，为相关研究和案件应用提供参考。

The aim of this study was to establish a comprehensive forensic reference for calculating likelihood ratios of different genetic relationships in the Chinese Han population. To achieve this, frequency parameters for 36 X-STR loci were determined. A notable limitation of previous literature reports was their reliance on small sample sizes, typically consisting of only 200-300 individuals. In contrast, our analysis incorporated data from over 1000 individuals sourced from 16 literature references, thereby ensuring a more robust and representative sample. The obtained allele frequency data for the 36 X-STR loci proved invaluable in forensic cases involving the Chinese Han population. This data was derived from an extensive collection of samples encompassing a total of 8 767 unrelated individuals hailing from diverse regions such as Guangdong, Henan, Yunnan, Beijing, Guzhou, Sichuan, Hainan and Hebei. Gene frequency parameters were carefully selected from these 16 literature sources to accurately represent the Chinese Han population. Multiple kits including Argus X12, Goldeye 17X，AGCU X19, Microreader X19, and Typer X19 were employed during data collection to ensure comprehensive coverage and accuracy. Across the 36 loci analyzed (including DXS6807, DXS9895, DXS10148, DXS10135, DXS8378, DXS9902, DXS6795, DXS6810, DXS10159, DXS10162, DXS10164, DXS7132, DXS10079, DXS10074, DXS10075, DXS981, DXS6800, DXS6803, DXS6809, DXS6789, DXS7424, DXS101, DXS7133, GATA172D05, GATA165B12, DXS10103, HPRTB, DXS10101, GATA31E08, DXS8377, DXS10134, DXS7423, DXS9907, DXS10146, DXS6797, DXS6804), a total of 572 alleles were identified with certain loci exhibiting notable increases in allele numbers such as DXS10135, DXS10134, DXS10148, and DXS10079, which indicated an increase by more than 5 alleles. To calculate allele frequencies across all 36 loci, a varying number (ranging from 1193 to 8767) of unrelated individuals were included in this study. DXS9895 and DXS6797 utilized a sample of 1193 unrelated individuals while HPRTB utilized 8767 unrelated individuals. This study significantly contributes to improving the diversity and accuracy associated with the 36 X-STR allele types. Moreover, the findings of this study provide an essential reference for calculating likelihood ratios in X-STR kinship analysis, consequently enhancing the reliability and credibility of kinship determination within the Chinese Han population.

The AGCU X Plus STR system is a newly developed multiplex PCR kit that detects 32 X-chromosomal STR loci simultaneously. These are DXS6807, DXS9895, linkage group 1 (DXS10148, DXS10135, DXS8378), DXS9902, DXS6795, DXS6810, DXS10159, DXS10162, DXS10164, DXS7132, linkage group 2 (DXS10079, DXS10074, DXS10075), DXS981, DXS6800, DXS6803, DXS6809, DXS6789, DXS7424, DXS101, DXS7133, GATA172D05, GATA165B12, linkage group 3 (DXS10103, HPRTB, DXS10101), GATA31E08 and linkage group 4 (DXS8377, DXS10134, DXS7423). A major advantage of this kit is that it takes into account linkage between loci, in addition to detecting more X-STR loci. In order to evaluate the forensic application of 32 X-STR fluorescence amplification system, PCR settings, sensitivity, species specificity, stability, DNA mixtures, concordance, stutter, sizing precision, and population genetics investigation were evaluated according to the Scientific Working Group on DNA Analysis Methods(SWGDAM) developmental validation guidelines. The study showed that the genotyping results of each locus were significantly accurate when the DNA template was at least 62.5 pg. Complete profiles were obtained for the 1∶1 and 1∶3 combinations. A total of 209 unrelated individuals from Southern Chinese Han community, consisting of 84 females and 125 males, were selected for population studies, and 285 allele profiles were detected from 32 X-STR loci. The polymorphism information content (PIC) ranged from 0.272 1 in DXS6800, to 0.910 5 in DXS10135, with an average of 0.679 8. DXS10135（PIC = 0.910 5）was the most polymorphic locus, with discrimination power（DP）of 0.916 4 and 0.987 1 for the male and female. The cumulative PD_F, PD_M, MEC_trio and MEC_duo values were all greater than 0.999 999 999. There were 78 different DXS10103-HPRTB-DXS10101 haplotypes among the 125 males, and the haplotype diversity was 0.9810. There was no significant difference in the cumulative PD_F, PD_M, MEC_trio and MEC_duo values whether considering linkage or not. In summary, the new X-STR multiplex typing system is effective and reliable, which can be useful in human genetic analysis and kinship testing as a potent complement to autosomal STR typing.

A gas chromatography-tandem mass spectrometry (GC-MS/MS) based method was developed for the determination of etomidate and metomidate in e-cigarette liquid. The samples were extracted with methanol and separated on a HP-5MS column (30 m×0.25 mm×0.25 μm). Etomidate and metomidate were detected by GC-MS/MS under multiple reaction monitoring (MRM) mode, and quantified by an internal standard method. The mass spectrometry parameters, including parent ions, product ions, and collision energy, were optimized in this experiment. The results showed that etomidate and metomidate exhibited good linearity within the range of 0.1 to 10 μg/mL, with R² no lower than 0.999. The recovery rates of spiked matrix were between 98% and 107%. The relative standard deviations (RSDs) for intra-day and inter-day precision were less than 8.83% and 9.34%, respectively. The concentrations of etomidate and metomidate in seven e-cigarette liquid samples ranged from 4.96% to 18.48%. This method is simple, easy to operate, with high extraction recovery, good reproducibility, and high sensitivity. It can be used for the detection and analysis of etomidate and metomidate in e-cigarette liquids.

This article introduces a case of asphyxial death caused by using plastic ties to tie (strangle) the neck. The deceased was a teenage female who lost contact with her family while climbing the mountain alone. The body was found on the mountain the next day. The deceased’s hands, feet, and neck were tied with plastic ties. After removing the ties, a 0.8cm wide circular closed cable groove was exposed on the neck. Mild congestion on the face of the deceased, patchy bleeding on the bulbar conjunctiva, more mushroom-like foam in the mouth, nose and trachea, no significant bleeding under the neck sulcus and muscles; Forensic histopathology revealed a decrease in the stratum corneum of the cervical sulcus skin, narrowing of cell spacing, elongation of cells and nuclei, pulmonary congestion and bleeding, focal interstitial bleeding in the heart, wave like changes in some myocardial fibers, edema of brain cells, and hypoxic changes in neurons; No toxic substances such as ethanol, barbital, phenobarbital, scobarbital, and tetramine were detected in the physical and chemical tests. Based on the above analysis, the deceased was found to have died from asphyxia due to external compression of the neck caused by plasticties. According to the analysis of signs such as more mushroom-like foam in the mouth, nose and trachea of the deceased, congestion in the face and mild bleeding, the neck bandage failed to completely close bilateral carotid arteries, veins and trachea, indicating that the death process of the deceased lasted for a long time. In addition, there is a difference of several hours between the estimated time of death using indicators such as the degree of digestion of gastric contents in this case and the time of crime confessed by the suspect. Through reviewing relevant literature, it was found that there is a significant error in using the degree of digestion of gastric contents to estimate the time of death in individual cases, which is related to factors such as personal constitution, on-site environment, and dietary conditions, It is suggested that forensic colleagues should not overly rely on a single indicator when inferring the time of death using early corpse phenomena. Instead, they should analyze factors such as the case, on-site environment, dietary conditions, and personal physique as comprehensively as possible.