Simulative explosion is usable for restoring the course of involving event and reconstructing the relevant case scene. Hence, three choices of LS-PrePost-based simulative modeling were here tried about explosion with spherical charging: the keyword *LOAD_BLAST-guided, the SPH-directed and the keyword *INITIAL_VOLUME_FRACTION_GEOMETRY- led, thus having their advantages and disadvantages analyzed along with the applicable scenarios. All the simulations were conducted under the optimal load of 1 kg TNT charged into three different shapes so that the generated blast air-shock waves (represented with peak overpressure) were able to unfold their variations. The finite element software LS-PrePost was utilized to put into a verified finite-element model for the explosion simulation to carry out, with every simulation only changing the shape parameter of charging. The ANSYS\LS-DYNA was the solver to respond the discrepant ways of spherical, columnar and square charging in turn, having obtained the peak overpressure at diverse scaling distances, acquired some representative simulation data and delivered a statistical chart to compare the differences between every group of peak overpressure data. It was shown that there was a closer peak overpressure generated from the columnar charging and the spherical with the scaling distance less than or equal to 1.0 m·kg^-1/3, while that from the square charging and the spherical tending to a bigger difference. If the scaling distance was increasing, the ratio of peak overpressures almost kept stable from the columnar charging against the spherical, while that from the square charging against the spherical revealing gradually increasing and changing a lot. Evidently, shape-different charging does impact the generated shock-wave peak overpressure, deserving of no ignoring. Therefore, when investigating the charging with an actual explosive case and the consequent destroying effect, the explosion simulation should be carried out with the charging shape as close to the actual cases as possible. For exploration about the problems approaching to an explosion simulation, it is also necessary to choose the appropriate modeling way and charging setup so as to ensure the accuracy and reliability of the analysis and results.

Presently, such an increasing demand emerges for the identification of complex genetic relationships in forensic practice that requires the combination of a variety of genetic markers, e.g., STRs, X/Y specific indicators, SNPs and mitochondrial DNA. Next generation sequencing (NGS) approach is able to integrate multiple genetic markers into one detection system, excelling the traditional capillary electrophoresis (CE) technology in overcoming the cumbersome operational procedures and experimental handling. Here, a typing panel, designated as DNATyper^TMNGSPanel v1.0, was developed with enclosure of human 29 autosomal STRs, 36 Y-STRs, 32 X-STRs, 71 Y-SNPs and the whole genome of mtDNA. Its validation was implemented under the guidelines of the Scientific Working Group on DNA Analysis Methods (SWGDAM), having evaluated the items of repeatability, accuracy, consistency, sensitivity, mixture and species specificity. For the developed DNATyper^TMNGSPanel v1.0, a consistency of 99.72% was shown to the detection with CE, plus the complete identical results coming true between the genic loci shared with it and the Forenseq™ DNA Signature Prep Kit. No allelic loss occurred to the DNA template of 0.5 to 10 ng, yet the respective 2 and 9 loci being lost with the 0.25 ng and 0.125 ng of template. Regarding to the mixture of male and female substances, the mixed ratio of 2׃1 had the the female’s begun to appear allelic loss, contrasting that the mixed ratios of 9׃1, 4׃1, 2׃1 and 1׃1 brought the positive detections to 54.72%, 81.13%, 98.11% and 100%; and the mixed ratio of 1׃4 made the male’s happen to allelic loss, opposite the mixed ratios of 1׃1, 1׃2, 1׃4 and 1׃9 rendering the positive detections to 100%, 100%, 90.24% and 82.93%. The test of species specificity proved that the developed DNATyper^TMNGSPanel v1.0 hardly amplified the DNA from pig, cattle, mouse, either the cynomolgus monkey or the rhesus one. In conclusion, the developed DNATyper^TMNGSPanel v1.0 is of high detection throughput, high sensitivity and stability, accurate and repeatable typing and good ability for mixed sample to detect. Also, it can deliver the genetic information related to paternity and maternity at the same time in just a single run of test with any common biological samples, hence eligible for boosting the capability of individual identification and efficiency of consanguinity determination.

As soon as ChatGPT came out, it attracted widespread attention. This article takes ChatGPT as an example, briefly describes the use, characteristics and advantages of large language models, and analyzes the current controversies, ethical dilemmas and information security risks. This paper focuses on the analysis of the possible applications of large language models in crimes, and discusses the use of ChatGPT to assist in the acquisition of criminal skills, the implementation of cybercrimes, phishing attacks, and the dissemination of false information. This paper also explores the use of ChatGPT at the law enforcement fields, including serving crime fighting, crime prevention, law enforcement decision-making, and law enforcement capacity building. This paper believes that law enforcement agencies should keep an open attitude, pay close attention to the impact of the application of artificial intelligence technology on crime, represented by ChatGPT. Law enforcement agencies should strengthen research and deal with ChatGPT from both aspects of “positive” and “negative” attitude, applying new technologies to help with law enforcement activities and improve efficiency.

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.

At present, most cases of guns misfire are caused by the old and loose gun parts and the failure of safety parts, which leads to guns misfire in the process of disassembly, wiping, touching and bumping. This paper introduces a case in which the naked firing trigger of the altered nail gun was hit by wrappage, causing death. Combining with the opinions of on-site investigation and autopsy, a simulation experiment was carried out to explore the formation mode of the shooting wound of the deceased and whether the gun misfire could be caused by hit. The whole process of gun misfire was restored by experiment, and the rules and characteristics of gun misfire were analyzed and discussed, which could provide reference for similar cases.

Identification of the cause of death is one of the essential tasks in forensic medicine. It is also the key for us to identify the nature of the case. An autopsy is a traditional method applied to find evidence of different causes of death. However, the traditional autopsy would damage the morphology of tissues and organs, affecting the morphological changes of injuries and diseases and leading to a bias in identifying the cause of death. Virtopsy is a novel technique developed in recent years. It is an amalgamation of forensic medicine and medical imaging. It has been known as a non-invasive autopsy method that uses imaging technology to obtain the surface and internal imaging information of the corpse to construct three-dimensional images of human organs and tissues, which provides imaging evidence to determine the cause of death, with the characteristics of non-invasiveness, objectivity, high efficiency, and storability. Virtopsy has been used to identify mechanical injury, traffic injury, asphyxia, disease, thermal injury, and so on. This paper reviews the application of virtopsy in identifying the cause of death and analyzes its advantages and disadvantages. We hope it will be the reference for forensic experts to determine the cause of death.

Fingerprint identification relates to relevant standards, involving specific features, developing technologies and the ever-exerting computer-based fingerprint automatic identification system (AFIS). For fingerprint features, those traditional level-2 ones play their roles in increasing juxtaposition to the level-3 ones with which the systematic basic researches have been already carried out on the related pores about their short-term tissue stability or the trackable others. Besides, the traditional level-2 features have been further subdivided and classified into some rare and more-detailed types. About AFIS, the existing version is facing many technical bottlenecks owing to its expansion of capacity and the recognition of numerous microscopic characteristics. Actually, the AFIS now available in China can only standardize the level-2 features, unable to effectively identify and compare those of level-3's. Even worse, the continuous enrollment of the fingerprint samples is causing the comparison accuracy of AFIS to decline, resulting in occurrence of the close-yet-nonmatched fingerprints which are indicative of two fingerprints, highly similar yet not homologous, commonly appearing more in the triangle zones. Such fingerprints are potential to cause a certain cognitive risk to identify incomplete fingerprints. Promisingly, a fusion algorithm has been developed about fingerprint's level-2 and level-3 features, realizing new functions such as the in vivo fingerprint detection. Furthermore, the rapid development of computer technology and establishment of fingerprint databases have made machine learning fulfilled to apply into fingerprint identification in academic and actual practice home and abroad. Usually, the machine learning takes large-scale fingerprint data as models for training and verification through different systems so that a likelihood ratio evaluation model is therewith developed to deliver the probability about fingerprint identity, hence bringing forth the fingerprint identification conclusion from absolute to relative. This paper summarizes the latest achievements related to the above aspects, putting forward the problems and envisioning the prospects for future progress trend regarding to fingerprint identification.

Synthetic cannabinoids are of hallucinogenic effect equivalent to or even stronger than that of cannabis, being listed under the first batch of new psychoactive substances controlled in China. There are many kinds of synthetic cannabinoids, among which MDMB-4en-PINACA and ADB-BUTINACA are recently the two ones of most active alkyl formyl indazole in the market. Such two synthetic cannabinoids have presumably not been reported about their metabolic researches in China. Thus, both the MDMB-4en-PINACA and ADB-BUTINACA were here probed into their metabolites from the blood and liver of rats. With 12 SD rats randomly divided into two equal groups: one for MDMB-4en-PINACA and the other for ADB-BUTINACA, each rat was fasted for 12 h and then intraperitoneally administered once by weight as per 1.0 mg/kg along with the two groups leaving one rat taken as the control that was not injected of drug yet executed just before administration. The remaining five rats in each group administered of drug were respectively killed at 5, 15, 30, 60 and 120 min after drug injection, having their blood and liver tissues received and successively analyzed into high performance liquid chromatography quadrupole time of flight mass spectrometry (HPLC-QTOF). The results showed that the experimental rats had MDMB-4en-PINACA metabolized into corresponding metabolites through double bond oxidative carboxylation, ester hydrolysis, 4-depentenylation and hydroxylation, with ADB-BUTINACA being metabolized through hydrolysis, 4-dealkylation, 4-butyl hydroxylation and hydroxylation. According to the response intensity of components in blood and liver tissue of rat, MDMB-4en-PINACA mainly converted into its metabolites from pentenyl oxidative hydroxylation (No. M6), pentenyl oxidative carboxylation (No. M7), methyl butyrate hydrolysis (No. M2) and further hydroxylation (No. M3/M4/M5) and dealkylation (No. M1), demonstrating its metabolic markers as M1 and M2. ADB-BUTINACA mainly turned into its metabolites from debutylation (No. A1), formamide hydrolysis (No. A2), butyl carboxylation (No. A3) and butyl hydroxylation (No. A4), with its metabolic markers being as A1 and A2.

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.

Fingerprint, one kind of the most important forensic evidence, is capable of having an individual identified. Therefore, it has played a crucial role in a police investigations and court litigation since it was admitted under jurisprudence. Regarding the verdict of fingerprint identification, there are currently only three propositions in China: recognition, exclusion, and inconclusiveness. Presumably, such handling roots its basis on the experience and practical situation of China's crime prevention and court processing hitherto, yet having caused abandonment or unusedness of amount-huge fingerprints collected of less than 8 minutiae from crime scenes due to their disqualification to the requirements of source threshold for fingerprint identification. However, these fingerprints are significant for police investigation and court processing. Thus, a probabilistic approach was described here with mathematic modeling to count minutiae by the related fingerprint image divided into fan-shaped sectors. Based on the statistics of 15 million fingerprint images, a function of probability density was fitted into fingerprint minutiae of all fan-shaped sectors and then modified under Bayesian Information Criteria, plus the addition of noises. Consequently, a probability was acquired towards identity recognition about a fingerprint under scrutiny. Through a trial of several examples, the results showed that the matching probability of fingerprint pairs was positively correlated to the quantity and stability of the analyzed minutiae yet negatively to the incidence of minutiae occurring inside the fan-shaped sectors. This study provided a novel attempt to rediscover the evidential value of those ‘useless fingerprints' displaying no sufficient details for identification but frequently found at crime scenes. Such an approach should be a crucial step for fingerprint identification from quality to quantity analysis, having significant potential to identify a criminal in combination with the quantifying applications of other forensic evidence.

Fingerprint, among the so-called “king of evidence”, always plays its crucial role in solving relevant cases. Therefore, fingerprint patterns are paid of incessant attentions from dactylgraphers. Here, the regularity of chiral symmetry of human ten-digit fingerprints was to explore with purpose to provide more reference information for fingerprint analysis and supply basic statistical data for investigation of fingerprint heredity. With collection of the fingerprint cards of 500 males' all ten fingers, 5000 fingerprints were consequently divided into 10 types of patterns according to six-step taxonomy. The symmetry of each fingerprint pattern was recorded about the name-same fingers from every ten-digit fingerprint card, together with the counts taken of the symmetrical samples, the isoform asymmetric ones and those simultaneously appearing on the name-same fingers of each pattern. SPSS software was chosen to analyze the correlation between pattern occurrence and the number of those showing symmetry. All the patterns were shown of higher symmetry rate with the ten-digit fingerprints, having particularly the arch pattern indicated of proneness to symmetry with thumb while the loop and/or whorl patterns more symmetrical with the little finger. Correlation analysis showed that the strongest correlativity linked to the index, little and/or middle finger while a relatively weak correlativity to the ring finger that was still demonstrated of high in terms of coefficient. In conclusion, good fingerprint-pattern symmetry emerges with the name-same fingers of left and right hand. The regularity of fingerprint-pattern symmetry revealed here should be able to provide more information in the case of fingerprints difficult to identify. Additionally, the chiral symmetry of fingerprint pattern may have its value in genetics and racial ascendancy.

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.

Etomidate is a hypnotic agent used for induction of anesthesia, characterized by rapid onset, short duration, and hemodynamic stability. It is widely used for anesthesia induction in elderly patients and those with cardiovascular disease and critical illness. The “2021 China Drug Situation Report” issued by the National Narcotics Control Commission pointed out that there is a situation of abuse of “smoke powder” in some areas, and its main component, etomidate, is identified as a drug substitute. However, there have been no reports of etomidate-related deaths in China. This article reports a case of a minor who died from respiratory failure due to exacerbation of bronchopneumonia after inhaling etomidate, for reference by peers. In forensic practice, attention should be paid to the adverse reactions of etomidate and the abuse of etomidate.

Fingerprint identification tends to be much attention paid on more detailed and specific features of fingerprint, e.g., the level 3 feature so that the further correlative evidence can be obtained against the involving suspect. Besides, the influential factors are gathering to link with the quality of fingerprints from crime scenes, the changes with identification standards and other challenges about real cases, having brought fingerprint examiners to shift their focus from macroscopic characteristics to those minute features. Moreover, the continuous progress of fingerprint development and extraction technology is gradually making the level 3 features able to recognize and identify, leaving such features to become an active research target. The done researches mainly emphasize on the basis about how the level 3 features play a role for fingerprint identification and their applicable conditions. Here, a comprehensive and in-depth analysis and introduction was carried out into the current status of the level 3 features' researching home and abroad with four aspects: basic attributes, reliability, automatic identification and identification attributes. Through an explicit description with the research process, a discussion was finally conducted on the prospect of level 3 features' researching, purposing to provide some references for the level 3 features to better integrate into fingerprint evidence and evaluation.

Immobile phone is presently of less attention for electronic evidence collection because it is commonly thought to be no storage function, leaving it little significance for evidence obtainment. However, the fact is that not all immobile phones aren’t able to store information. For immobile phones equipped with storage chip, some valuable information (e.g., calling details) can still be extracted from them. Actually, immobile phones are among the criminal tools widely utilized by culprits in current telecom network crime. Therefore, the relevant calling information recorded in the case-involved immobile phones will play an important role for the case to solve. Here, electronic forensics were carried out about extracting and analyzing the calling information recorded in storage chip of the case-involving immobile phone. From the disassembled immobile phone, the memory chip was taken out to have the physical image ghosted so that the calling information data were capable of being extracted out of the ghosted image with WinHex software. The program was written by Python to sort out and display the original data about the ghosted image, together with deep excavation into the potential calling rules, calling duration and other information. Consequently, immobile phone should not be ignored in investigation of telecom network crimes, and the Python program is indeed a good helper for extracting electronic evidential data out from immobile phone.

Fingerprint seals or films, made from people's real fingerprints, are at times used for related individuals to do their business conveniently, yet leaving behind the risk for violators to forge these fingerprints to seek illegal interests. At present, the fingerprint identification mainly focuses on two aspects: one is the traditional morphological comparison; the other is the emerging deep-learning recognition. Unfortunately, there is still a lack of scientific, effective, mature and stable examination methods to distinguish the genuine fingerprints from those fake ones which are often appeared with their red-ink-displayed versions on documents. In principle, genuine fingerprints definitely contain the substances transferred from their human donors, yet the fake fingerprints only contain substances from the used ink. Therefore, an identification method was here designed to discern the genuine and fake fingerprints displayed with red ink on documents, and verified of its scientificity and effectiveness through experiments. Specifically, the fake fingerprints were made via photosensitive fingerprint seals imbibing red ink and then pressing against the paper carriers, with the genuine fingerprints being prepared by relevant fingers directly pressing against red inkpad and then imprinting onto paper carriers. Both the genuine and fake fingerprints were placed for designated durations of time. The transfer medium was used to convey the red fingerprints (both geunine and fake), and treated with ninhydrin operation under two modes: one, developing the fingerprints through reaction of fingerprint-harbored substances (if present) with the fingerprint developer along with the transferring process; the other, first having the fingerprints transferred onto the medium previously soaked with related working fluids and then developed via fingerprint developer. Consequently, the transferred fingerprints were observed of their changes before and after displaying treatment (whether the Ruhemann's purple appeared on the transfer medium). The results showed that: 1) two modes were both able to successfully transfer the fingerprint substances and develop the fingerprint on the transfer medium, demonstrating that genuine fingerprint did result in the Ruhemann's purple appearing while none with the fake fingerprint; 2) the mode two displayed better processing effect than the mode one; 3) the mode two successfully transferred the fingerprints left for 1, 2, 7, 15 and 30 days, and had Ruhemann's purple emerged when ninhydrin treated to the relevant medium transferred from genuine fingerprint while none from the fake fingerprints. Evidently, there are differences in the distribution of componential substances between genuine and fake fingerprints. A method has been herewith established to identify genuine and fake fingerprints on documents based on the principle of fingerprint substance transferring, verifying that the identification can be realized with the fingerprints retained for legacy time of 1, 2, 7, 15 and 30 days.

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.

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.

Spiker bolter and nail shooting pill are widely used with house decoration, easy to be restructured. Consequently, criminals are often found to adopt these devices among the gun related cases. During case investigation, such questions are thus very likely to meet as whether the case-concerned bullet is restructured from nail shooting pill and what the related type is, which the original manufacturer of the restructured nail shooting pill is. Therefore, it is necessary and important to learn about the basic information of nail shooting pill. Accordingly, a survey was here carried out for unveiling the information about the main domestic manufacturers of nail shooting pills in China, their relevant main types and raw materials for production, and the process to produce them, especially putting the focus on the raw materials and crafts used with different manufacturers. Such a task done here should be helpful to link the case-involved restructured nail shooting pill with its original manufacturer and further provide information about the suspect in crime investigation.

Determining the primary crime site is of importance for the crime scene investigation. Bloodstain is one of the most common types of evidences in homicide scene. Through the analysis of bloodstain patterns at the crime scene, investigators can accurately reconstruct the sequence of events in crime scene and determine the primary crime site. Based on the bloodstain patterns at the crime scene and the associated scene of a homicide case, the investigators comprehensively analyze the shape, type, pattern characteristics, spatial relationships to each other and the surrounding scene of the blood stains. Analysts reasonably eliminates the possibility of suspect disposing the body, accurately determines the first site of the homicide case, provides key technical evidence for narrowing the search for evidence and successful prosecution of the suspect, and provides crucial information for the investigators to identify the first crime scene and the associated scene of this complex and difficult homicide case.

In all kinds of shooting incidents, it is more common for ricochet to cause casualties or property losses. At the scene of ricochet shooting, the bullet head and relevant marks have been deformed to varying degrees, affecting the trace inspection and on-site ballistic analysis. This paper investigates and analyzes the jumping bullet scene caused by a police officer’s 92 pistol shooting in the process of law enforcement, introduces the quantitative characteristics of the jumping bullet trace into the gunshot jumping bullet analysis, and tests the size and morphological characteristics of the jumping bullet point trace and the bullet deformation surface trace. During the process of jumping bullet shooting, the bullet head penetrated multiple wooden objects. By measuring the size and distance of the firing entrance and exit traces and the jumping points on the relevant objects, the incidence angle and the rebound angle of the jumping bullets are accurately calculated. The ballistic analysis is carried out in combination with the site layout and distance, and the location of the firing points and firing angle are restored, providing a scientific basis for ascertaining the nature of the case. This paper provides a reference for the investigation, evidence collection, and event characterization of such incidents.

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.

A novel way has been here developed for latent fingerprint to detect through the hierarchical nano-structural powders of VO₂ (vanadium dioxide). Such the innovative nano powders were synthesized from a one-step solvothermal reaction with the raw materials of vanadium acetylacetone and hydrogen peroxide, successively having them characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The synthesized VO₂ powders were of blue color, high purity and uniform morphology with submicro-spherical structure consisted of nanorods. The diameter of the submicro-spheres was about 450~650 nm. The so-prepared VO₂ powders were dusted onto different surfaces where to reveal the collected sweat and oily latent fingerprints that were compared of their development against the traditional powders. Such the nano powders brought the latent fingerprints to turn up their visions of high contrast, good definition and coherence that the fingerprints' detail features were shown remarkable, which can be attributed to the high selectivity and sensitivity of the VO₂ powders to the fingerprint-harbored residues. Compared with the traditional powders, the VO₂ hierarchical nano-structures developed better definition of latent fingerprints on glass slide and transparent plastic cup than did gold/silver/magnetic powder, and so did they on aluminum foil than gold/silver powder as it was deemed of their specific structure to play effect. In general, the smaller and more regular the size and shape of the VO₂ nano-particle, the stronger the interaction force between the particles and fingerprint-harbored residues (water, grease, etc.). The VO₂ hierarchical nano-structures demonstrated of not only characteristic of strong adsorption of nanostructured powders but also avoiding the agglomeration of nanoparticles and reducing the harm of inhaling nanopowders during operation. Moreover, their uniform spherical morphology was proved of more likely interacting with fingerprint-harbored residues. Conclusively, the fabrication for VO₂ hierarchical nano-structures is facile, low-cost and no impurity of the prepared products. Sweat and/or oily latent fingerprints can be effectively developd on both nonporous and porous surfaces using the VO₂ hierarchical nano-structures, showing themselves of better definition on glass slide, transparent plastic cup and aluminum foil than using traditional powders.

In fire scene, the discovery and extraction of evidential fingerprints are valuable for identifying the relevant suspects or responsible persons. However, the fire scene is usually destructive and complex, resulting in the display of fingerprint there being difficult. Overseas scholars have explored the applicability of displaying reagents and ash removal for fire-baked fingerprint to develop. Currently, there is a lack of relevant researches on portable instruments to extract the on-site fingerprints at fire scene. In addition, few researches have seemed to conduct about the effectiveness of fingerprint display after long-duration exposure to high temperature in fire scene. Targeting at this situation, an experimental research was carried out, with the quartz resistant to high temperature being selected as the fingerprint carrier to explore portable instruments to recover the fingerprints survived at fire scene. The fingerprint samples were prepared under high-temperature conditions simulating the scene of a fire. Two methods, the optical nondestructive exposure and "502"glue fuming, were used to explore the impact of high temperature on fingerprint display. The results showed that the longer the baking time at the same temperature/the higher the baking temperature at the same time, the more serious the fingerprint damage. Optical nondestructive exposure can obtain good extraction results for fingerprints baked below 500 °C for about 10 minutes, or below 400 °C for 20-30 minutes, yet appearing worse presentation than the “502” glue fuming under all experimental conditions. Therefore, this research can provide reference for suitable choices (e.g., the two methods adopted in this research) to extract and display the evidential fingerprints in fire scene.