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Exosomes, which are extracellular vesicles with a double-layer membrane, play significant roles in biological processes. They act as tiny carriers, capable of transporting a wide range of genetic materials and metabolites, including DNA, RNA, proteins, lipids, etc. Hypoxia, a state of low oxygen availability, is a powerful environmental factor that triggers significant changes in exosomes. Their composition, secretion process and overall functionality will all be drastically affected under hypoxic conditions. In the realm of forensic pathology, the precise identification of death from mechanical asphyxia (DMA) has always been a major challenge. The corpses of individuals who have died from mechanical asphyxia often lack distinct and characteristic signs that can directly point to this particular cause of death. This absence of specific indicators makes it extremely difficult for forensic pathologists to achieve precise diagnosis, which brings trouble to the criminal investigation and court trial of DMA cases. In this paper, we conducted a comprehensive review of the hypoxia-induced changes of exosomes and discussed the benefits, limitations, and feasibility of application of these changes to precise identification of DMA. Through this in-depth discussion, we hope to offer new perspectives and directions for relevant studies, thereby contributing to the advance of forensic pathology.
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Industrial explosives are usually strictly controlled, with many sales links and high prices, which bring great profits to the homemade explosives. In recent years, cases of illegal manufacturing, trading, transportation and storage of ammonium nitrate explosives have frequently occurred. The raw materials for homemade ammonium nitrate explosives are widely available and easy to obtain. These result in the complex compositions and formulations. Accurate qualitative and quantitative characterization of its composition is of great significance for comparison, tracing and case investigation. Powder X-ray diffraction (PXRD) has become an efficient method to identify the component. However, it is still in the qualitative stage, i.e. matching of the phase and lack of quantitative method to illustrate the content of each substance in mixtures. In this paper, a quantitative method based on PXRD is described, including pre-processing method, sample preparation, instrument parameter settings and full spectrum fitting method. Firstly, the crystalline phase and amorphous phase components contained in the sample are accurately judged. Subsequently, Rietveld refinement method is used in which multi-dimensional factors such as structural parameters, peak parameters, instrument parameters are all included. The differences between the measured pattern and the calculated pattern is the target function and the optimization algorithm is used to obtain model parameter. After refinement fitting, the best structural parameters and other parameters including content of each component are all identified. The method can realize the quantitative characterization of powder, granular, or block solids. It can provide an important basis for the comparison and tracing of such evidences, so as to further correlate the cases.
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Rapid DNA analysis technology represents an innovative approach by integrating multiple stages of the DNA analysis process, including DNA extraction, multiplex PCR amplification, and capillary electrophoresis. This analysis technology enables the automatic execution of all these processes, eliminating the need for manual intervention. Commercially available rapid DNA testing systems can simulate the laboratory environment through the internal environment offered by automated equipment. This advancement liberates the entire testing procedure from the stringent environmental conditions typically required in a DNA level three laboratory. In this article, the performance of the domestic fast integrated forensic DNA analyzer Quick TargSeq™ was verified under extreme environments. The tested instrument was loaded onto an SUV for both on-vehicle and on-the-move testing. The tests ranged from an altitude of 500 m on the plain to a peak altitude of 3800 m, which included 4 park-and-test points (with 1 reference point on the plain) and 5 on-the-move test trips. Throughout the test, there was a mix of rainy and snowy weather, with environmental temperatures dropping as low as -1 ̊C. A total of 36 results were collected, which included 2 from reference points at plain, 4 from on-the-move trip at plain, 18 from park-and-test points at highland and 12 from on-the-move trip at highland. Taking all the collected data into calculation, the loci detection rate of the test is 99.21% and the loci accuracy is 100%. The test results indicate that the Quick TargSeq™ DNA system is highly environmental adaptable and capable of operating effectively in both highland and on-vehicle settings.
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Fingerprints are a crucial form of forensic evidence at crime scenes. Blood fingerprints, as a type of fingerprint trace, possess significant forensic value for identification via DNA analysis and fingerprint pattern matching. This study discussed the enhancement effects of lac dye on bloody fingerprints. In the experiments, a solution with 0.25% lac dye and a 5% acetic acid (pH2.55) was applied to enhance the bloody fingerprints on 12 common substrates, as well as aged bloody fingerprints with different drying time and bloodstain concentrations. The enhancement effects were compared. The results demonstrate that lac dye has practical value in enhancing blood fingerprint, with good enhancement effects and high sensitivity on most non-porous substrates, and it is also suitable for enhancing old and low-concentration bloody fingerprints. However, its performance on porous substrates is relatively moderate. This dye solution is simple to prepare, easy to operate, and convenient to store, making it suitable for the visualization and extraction of bloody fingerprints during criminal scene examinations.
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Against the backdrop of the rapid development of big data and artificial intelligence, the field of footprint examination urgently requires advancements in professionalization and informatization. Currently, research on the identification methods of barefoot footprints has made certain progress, but the automatic recognition of shod footprints remains a tough challenge in the field. Therefore, this study introduces the Surf algorithm to explore its potential application in the automatic recognition of shod footprints. More specifically, the study employs the Surf algorithm to perform feature matching on four types of footprint images (i.e., the same person with the same shoe, the same person with different shoes, different people with the same type of shoes, and different people with different shoes), and conducts an in-depth analysis of the similarity between footprints by mapping the matching points through geometric transformations. The results show that footprints from the same person with the same shoe exhibit a significantly greater number of Surf feature point matches compared to other types; after geometric transformation mapping, footprint images from the same person, the same shoe and same time have a greater number of matching points, with accurate matching positions, while footprints from different people exhibit fewer matches. Additionally, even when considering footprints from the same person, those formed in closer time intervals have more matching points than those formed further apart in time. In summary, the Surf algorithm exhibits efficiency and reliability in recognizing footprints from the same person with the same shoe.
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Indirect fingerprint forgery refers to the creation of fake fingerprints using pre-existing finger marks as the template, which poses a great risk in reality due to the lack of need for the subject’s cooperation and its strong concealment. However, applying indirect forgery techniques to electronic evidence collection for the purpose of unlock electronic devices can significantly facilitate the forensic process. This paper investigates the effectiveness of bionic fingerprint films made by indirect forgery methods in bypassing security on various electronic devices equipped with fingerprint recognition systems. In the experiment, visible and latent fingerprints already formed were collected as samples to create ordinary silicone and capacitive silicone fingerprint films, and these were used to crack smartphones, tablet computers, fingerprint attendance machines, and smart door locks. The study also examined the impact of fingerprint sample quality, conditions for making photo-sensitive stamps, and the production conditions of fingerprint films on the effectiveness of cracking. The results show that the fingerprint film, produced by scanning, printing, and engraving photo-sensitive stamps from pre-existing real fingerprint samples, can successfully unlock a series of electronic devices equipped with fingerprint recognition systems with a high success rate. The production process of indirect forgery silicone fingerprint films is convenient and quick, providing a method to crack related electronic devices without disassembly or intrusion into the system, thus better protecting the originality and integrity of evidence. However, it is also necessary to recognize the hazard of this method and urge the public to prioritize the security of their fingerprint information in their daily lives.
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In recent years, the rapid development of artificial intelligence (AI) has brought unprecedented opportunities and challenges to scientific and technological research in various fields. The cross-integration of forensic toxicology and AI has increasingly become a research hotspot of forensic science, providing new ideas and methods to solve the problems of traditional forensic toxicology. In this paper, relevant researches in recent years have been reviewed, focusing on the research progress of AI in toxicological research such as on-site investigation of poisoning, toxicant screening and qualitative and quantitative detection, toxicity prediction, toxicokinetics, toxicants interaction, as well as the identification and characterization of involved personnel in cases, and the challenges faced by AI technology in the field of forensic toxicology have also been analyzed, in order to provide reference for AI technology to better serve the research and application of forensic toxicology.
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Gamma-hydroxybutyrate (GHB) is a psychotropic drug listed in the United Nations 1971 Convention on Psychotropic Substances and China’s Regulations on the Administration of Narcotic Drugs and Psychotropic Substances. GHB has a strong inhibitory effect on the central nervous system, which can cause temporary memory loss, nausea, vomiting, hypersexuality, hallucination and even death. It is a more common chemical synthetic drug in entertainment venues. In recent years, GHB and its precursor γ-butyrolactone (GBL) are often used by criminals, leading to intentional injury, traffic accidents, rape and other malignant cases, causing a series of serious public health problems and social security problems. GHB is a normal endogenous substance in human body, which can be increased by exogenous intake. This means that timely sampling is needed to ensure the accuracy of the test results. If the concentration of the biological material cannot be detected in time, it cannot be proved that the victim or suspect had exogenous GHB ingestion. At the same time, the metabolism of GHB in human body is fast, the metabolites are complex, and the test window is short, which brings challenges to the police inspection and identification. In the face of the social reality that the cases of “anesthesia rape” and “anesthesia robbery” involving GHB continue to occur frequently, it is particularly important to study the testing and identification technology of GHB. This paper introduces the abuse and control of GHB at home and abroad, points out the difficulties in the detection and identification of GHB, and then summarizes the research progress in the detection and identification technology of GHB in blood, saliva, hair and urine. The endogenous levels of GHB in the biological specimens above and the critical concentrations of GHB after exogenous intake are enumberated, which can help forensic experts to exclude false positive results and assist in determining GHB abuse, in order to provide reference for the anti-drug work of public security in China.
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In the field of forensic genetics, the interpretation and analysis of mixed STR profiles have been a focal point of research due to their complexity and challenges, playing a crucial role in the investigation of difficult cases. To improve the accuracy and speed of mixed STR profile separation and to adapt to the effects of low template quantities under complex profile noise, domestic and internationall scholars have conducted a series of studies on mixed STR profile separation. In recent years, artificial intelligence methods have shown promise as a new solution for mixed STR profile separation. This paper reviews the research progress related to mixed STR profile separation, highlights the key and challenging aspects of the separation process, and proposes potential applications of artificial intelligence algorithms in this field. This paper aims to provide reference and insights for solving the problem of mixed STR profile separation using artificial intelligence methods.
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With the widespread application of high-throughput sequencing technology in the field of forensic genetics, effectively handling the large and complex datasets generated by high-throughput sequencing has become an urgent issue. This paper extends the Genome Analysis Toolkit Best Practices guidelines based on multiplex targeted sequencing, focusing on four genetic markers commonly used in forensic genetics: short tandem repeats (STR), single nucleotide polymorphisms (SNP), insertions and deletions (InDel), and mitochondrial DNA (mtDNA). It elaborates on how to analyze these four genetic markers from FastQ raw data to the final analysis report in three parts: data quality control, construction of necessary analysis files, and data analysis. A bioinformatics analysis workflow suitable for high-throughput sequencing raw data in the forensic genetics field is introduced, providing a feasible approach to effectively address the challenges of high-throughput sequencing data analysis. This workflow not only makes it possible to independently analyze high-throughput sequencing data, but also prepares for subsequent analyses such as population genetics if needed, offering more diversified technical support for the practical application of forensic genetics.
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In recent years, with the rapid development of forensic virtual anatomy technology, MSCT (multi-slice computed tomography) has gradually become an important auxiliary means of forensic examination. Concurrently, MSCT image post-processing technology has also gained widespread application in forensic pathology, clinical forensic medicine, and forensic anthropology. Image post-processing technology can transform digital images into more understandable and valuable information that is easier to comprehend and apply. It can also enable the accurate measurement of the length, angle, volume, area, CT values, and other parameters of the target part, which provides technical support for the evolution of expertise from an empirical discipline based on subjective experience to digital medicine based on objective data. Because MSCT image post-processing technologies are diverse, forensic personnel need to understand their advantages and disadvantages. They should then choose the most suitable method to achieve the best results. Practice has shown that, depending on the different observation objectives, selecting the most appropriate post-processing technology can display the target image more comprehensively and objectively. This can help to reduce missed diagnoses and misdiagnoses, thereby improving the detection and accuracy rates. In this paper, the existing image post-processing techniques are summarized, and the advantages, disadvantages and current application situations of MPR(multi-planar reconstruction), VR(volume rendering), CPR(curved planar reconstruction), SSD(shaded surface display), and MIP(maximum intensity projection) are introduced to provide technical references for related work. In daily work, MPR and VR are most frequently used. MPR is highly authentic, VR has a high data utilization, and both most closely conform to visual effects. The other post-processing techniques also have their own advantages, and it is recommended to select and use them in combination according to the characteristics of the target part. Although image post-processing technology has many advantages, it also has some limitations. Its detection rate for soft tissue injuries and hemorrhages is slightly weak, so sometimes it needs to be combined with MRI examinations or autopsies.
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Before the widespread use of digital photography technology, photographic negatives captured on photosensitive film served as crucial evidence in solving old and unresolved cases, providing important information for the successful resolution of cases. However, early black-and-white evidence negatives, taken during case proceedings, were prone to severe mold damage due to factors such as storage conditions, leading to blurred prints and significantly impeding the extraction of forensic details. This paper introduces a restoration method for severely mold-damaged negatives, which involves using a high-boiling-point liquid material with diisooctyl phenyl phosphite (DPOP) as its main component. Applying this material to the surface of the moldy negatives fills in the roughness caused by mold and eliminates the diffuse reflection of visible light caused by mold spots, effectively restoring the image quality on the damaged negatives. Meanwhile, the method is reversible. Once a clear and complete image is obtained, the applied restoration material can be removed, allowing the negative to revert to its original state and ensuring the integrity of the evidence. Employing this method, we successfully recovered the image on an evidence negative from a serious criminal case, fully reproducing the forensic information recorded on the film over 30 years ago and establishing a solid foundation for the case’s successful resolution.
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International forensic science organizations (associations) include the International Forensic Strategic Alliance (IFSA), the International Association of Forensic Science (IAFS), and others. Since its establishment in 2004, the International Forensic Strategic Alliance has expanded into a multilateral partnership alliance of six operating regional forensic science networks and three strategic partners, as its collaborative capabilities and international influence growing. This paper introduces the basic information of the International Forensic Strategic Alliance and its members. Using the Asian Forensic Sciences Network (AFSN) and the Senior Managers Australian and New Zealand Forensic Laboratories (SMANZFL) as examples, it analyzes the connections and distinctions between alliance members, including the topics of interest at the past five annual conferences, as well as similarities and differences in the focus areas of forensic science networks in different regions. This paper also reviews China’s relationship with the International Forensic Strategic Alliance, focusing on the development trends of forensic science domestically and internationally, and looks ahead to the prospect of China’s participation in international forensic science organizations (associations), with the aim of providing insights for promoting the internationalization of forensic science in China.
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In recent years, with the rising prevalence of telecommunication network fraud cases, the law enforcement agencies have significantly increased their efforts to combat the development and utilization of fraudulent technologies. Consequently, criminal groups have heightened their counter-surveillance capabilities. To evade law enforcement, many criminal groups chose to set up their own instant messaging (IM) services on servers and encrypt the transmitted data to prevent authorities from obtaining incriminating evidence, such as registration information and chat logs, through the third-party companies. This paper introduces a case study involving the decryption of chat data encrypted with the Blowfish+CBC mode algorithm on a MongoDB database, aiming to provide a reference for the investigation of similar telecommunication network fraud cases.
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This paper introduces the examination process of stab and cut marks on the outer jacket of a cable in a case of railway cable theft involving cutting. Through the examination and analysis of the characteristics, directions, locations, and interrelationships of the marks left on the outer jacket of the cable at the crime scene perimeter, the types of tools and methods used by the suspect in committing the crime were identified, which were determined as matching the broken sickle found at the scene, providing crucial technical support for the investigation and prosecution of the case. Additionally, it offers valuable insights for the inspection and identification of marks on cable jackets and the preparation of comparative samples in similar cases.
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At present, the research on gasoline poisoning mostly focused on gasoline identification and detection. However, the autopsy and internal distribution were less studied. The purpose of this article is to provide reference data and pathological information for the determination of fatal poisoning caused by gasoline. Toxicological examination was performed on a deceased case of inhaling gasoline. The automated thermal desorber-gas chromatography mass spectrometry was used for qualitative and quantitative analysis of gasoline in the in vivo samples. The detection technology, the qualitative and quantitative evaluation methods of gasoline, the symptoms and mechanisms of gasoline poisoning and the internal distribution of fatal cases were summarized. The toxicology analysis results showed that, gasoline components were detected in the oral and nasal contents, lung, stomach contents, esophageal contents, pleural effusion and heart blood of the deceased. The concentrations in the esophageal contents and pleural effusion were 23.89 μg/mL and 26.7 μg/mL, respectively. Except for the oral and nasal contents and heart blood, the gasoline components in the in vivo samples showed a pattern of more light components and less heavy components, which was slightly different from control gasoline. As a low-toxicity narcotic poison, the mechanism of gasoline poisoning is mainly related to its physical properties such as high fat-solubility and high volatility. The symptoms of gasoline poisoning are non-specific. However, gasoline poisoning is not difficult to determine basing on occupational background investigation and odor identification of clothing and environment. According to the experience, the degree of poisoning is closely related to intake, so accurate quantification and the lethal dose of gasoline are key factors. Therefore, gasoline detection of the in vivo samples and literature review contributed to accumulate forensic toxicological data, and also provided reference for forensic toxicologists to deal with similar cases.
