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The objective likelihood ratio (LR) paradigm of DNA feature is the theory and method for interpreting the evidential significance of DNA analysis findings. It is a typical representative of the forensic Bayesian likelihood ratio paradigm. The DNA feature’s objective LR is the ratio of the probability of DNA feature findings quantitatively assigned based on model and data, in the context of two alternative propositions typically advocated by both of the prosecution and defense. The hierarchy of propositions includes the sub-sub source level, sub-sources level, sources level, and activity level. The LR of DNA feature findings expresses the relative support direction and strength of the DNA findings for the propositions of the prosecution and defense, providing quantitative evidence value for decision-makers to determine disputed propositional facts. Decision makers will determine the propositional facts without reasonable doubt, based on the LR opinions of DNA findings or the posterior probability of the propositions derived from LR opinions and Bayesian laws, and combined with other evidence in the case. The DNA feature’s objective LR paradigm is completely different from the traditional paradigm that we are used to in terms of scientific logic, opinion formation, expression, understanding, and reasoning applications, which poses new requirements and challenges for forensic examiner and decision-makers.
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The establishment of a scientific quantitative evaluation system for fingerprint evidence, especially how to introduce the statistical method of likelihood ratio into the digital representation of fingerprint identification, is a hot issue in the current theoretical and practical research of forensic science. The construction of a scientific and effective likelihood ratio evaluation model for fingerprint evidence requires rich same-source and different-source fingerprint databases to obtain the likelihood function with a stable distribution law, thus, the quality of the same-source and different-source databases directly affects the performance of the likelihood ratio model. By using the live-scan fingerprint collector and screen recording software to obtain more than 1 000 distorted fingerprint images for each fingerprint in different distortion modes, a total of 200 000 same-source fingerprints are obtained from 200 simulated fingerprints, which constitutes the same-source fingerprint database; and the different-source fingerprint database consists of ten million people’s ten-fingerprint database in policing practice. On this basis, the automatic fingerprint identification system is utilized for query and comparison, and the comparison score data are evaluated. The experimental results show that the fingerprint data of different distortion modes have significant differences; the degree of pressure and the impressing time have little effect on the comparison scores of fingerprints. From the results of statistical analysis of the total number of samples and the subsample data after different degrees of reduction, it can be seen that the number of same-source samples of each fingerprint can still form a stable distribution law when the number of fingerprints is as few as 155. Therefore, the database we built is rich in the number of same-source and different-source fingerprints, reasonable in structure, and has the data basis for forming a stable distribution law, which is helpful for the subsequent establishment of the likelihood ratio evaluation model.
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Peganum harmala is a plant widely distributed in the arid areas of northwest China, the alkaloid harmaline and harmine contained in which shows toxic effects in human such as acute central neurological symptoms, cardiovascular effects and death. In order to meet the qualitative and quantitative detection requirements for cases of Peganum harmala poisoning, a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the simultaneous detection of harmaline and harmine in human whole blood. The blood samples were deproteinized with acetonitrile, separated on an analytical column (Agilent SB-C18 100 mm×2.1 mm×1.8 μm) with 0.1% formic acid and acetonitrile as the mobile phase by gradient elution at a flow rate of 0.4 mL/min, determined by electrospray ionization (ESI+) and multiple reaction monitoring (MRM) modes after diluted and filtrated through membrane, and quantified by external standard calibration method. The result showed that there was good linear relationship for harmaline and harmine in human whole blood over the range of 10 to 1 000 ng/mL (R2>0.999). The limit of detection (LOD) and quantitation (LOQ) of harmaline and harmine in human whole blood were 3 and 10 ng/mL, separately. At 10, 100, and 500 ng/mL, the recoveries of harmaline and harmine showed a range of 84.9% to 97.0% and the matrix effects of different human whole blood were less than ±25%，with the precisions of intra-day and inter-day ranged from 3.6% to 9.8% and 7.3% to 12.8% respectively, and the accuracy ranged from 2.4% to 9.5%, which meets the general rules for forensic toxicology in China. The method was successfully applied to a real case of abnormal death caused by improper use of Peganum harmala, where the concentration of harmaline and harmine in the blood of the deceased were detected to be 1.2 μg/mL and 0.2 μg/mL respectively. In conclusion, the results of this study could be applied to forensic science on the simultaneous detection of harmaline and harmine in human whole blood with the advantages of simplicity and accuracy and provide reliable technical support for the subsequent investigation of practical cases.
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Adult bone age assessment is an important part of forensic anthropological age assessment, which includes items such as adult living body bone age assessment, unknown cadaver bone age assessment, and ossified cadaver bone age assessment. Traditional assessment methods are mainly applicable to unknown and ossified cadavers. Adult living body age assessment requires extracting high-definition models of pelvic volume reconstruction (VR), and then referring to traditional methods for assessment. The purpose of this study is to explore the necessary conditions for establishing a high-definition model extraction method for pelvic volume reconstruction, which solves the problem of setting parameters for multi-slice spiral CT (MSCT) scanning and reconstruction in the process of pelvic 3D imaging sampling for adult bone age assessment. This study used Precision32 (Kaiying Company) MSCT with protocol fixed tube voltage of 120 kV, tube current of 250 mA, pitch of 1.05, layer thickness of 1.1 mm, spacing of 0.8 mm, and matrix 512 × 512 to scan fresh corpse pelvis, and adjust reconstruction parameters such as filtering, layer thickness, layer spacing, matrix, etc. to compare the clarity of pelvic volume reconstruction images, and select the necessary parameter values. The research results indicate that filtering, layer thickness, layer spacing, matrix, etc. have a significant impact on the clarity of volume reconstruction images. Choosing pelvic filtering, thin layer thickness, short layer spacing, and large matrix can improve the clarity of pelvic VR models. Therefore, under the premise of using scanning parameters such as protocol tube voltage and tube current, it’s necessary to choose pelvic filtering, thin layer thickness, short layer spacing, large matrix, etc. to establish a high-definition model for pelvic volume reconstruction.
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When dealing with major emergencies, it poses the greatest challenge for public security law enforcement departments to timely, accurately and intelligently process the massive and complicated multi-source heterogeneous police data transmitted by various front-end collection devices. Under the background of major emergencies, the effectiveness of police work hinges on the real-time data collection, the accuracy of processing, and the intelligence of decision-making. This necessitates a police data system capable of rapid response, accurate analysis, and intelligent decision-making. However, current police data processing systems still rely on manual screening and analysis, resulting in inefficiencies during major incidents. Therefore, how to leverage massive police data and fully extract valuable information from it is one of the difficult problems to be solved in the process of police modernization. This paper first conducts a thorough analysis of the current situation and problems of police data application in China’s police work during major emergencies, followed by the proposal of countermeasures for the in-depth application of police data. Ultimately, digital twin and knowledge graph technology are combined to realize the intelligent analysis and application of massive police data, thereby establishing a new policing model with capabilities for security risk perception and situation analysis.
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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.
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The structures of the effective components in the white crystals and colorless liquids, which were seized by Luzhou drug enforcement department, were analyzed by gas chromatography-mass spectrometry, liquid chromatography- quadrupole time-of-flight tandem mass spectrometer, nuclear magnetic resonance and Fourier transform infrared spectroscopy. Through sample analysis, it was found that the spectrograms of the two substances had no matching data with the existing database, and had a high degree of similarity. The accurate molecule mass of the two substances measured by liquid chromatography-quadrupole time-of-flight tandem mass spectrometer were the same, but the two substances have different retention times. In the next step, after analyzed by liquid chromatography-quadrupole time-of-flight tandem mass spectrometer and secondary mass spectrometry, it was found that in the secondary mass spectrum of white crystals, there were toluene fragments, and in the secondary mass spectrum of white liquids, there were phenyl fragments and ethylamine fragments, so it was inferred that the two substances were isomers. The proton attribution and carbon type of the two substances were analyzed by nuclear magnetic resonance and the carbonyl, amino and other functional groups were confirmed by infrared spectrum. The main component in white crystals was 2-(o-methylphenyl)-2-(methylamino) cyclohexanone, and the main component in colorless liquid was 2-(phenyl)-2-(ethylamino) cyclohexanone. The two substances are the new psychoactive substances of phenylcyclohexylpiperidine with the most active abuse currently, but the relevant data have not been reported in domestic literature, and there is a lack of relevant structural data reference. This paper comprehensively tested the structural data of the two substances, providing reference for combating new drug crimes and controlling the two substances.
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Sex determination by measuring bones is an important part of forensic anthropology, and a database of bones from one population at one time is often not applicable to another. Teeth and jaws are more stable than other bones and tend to be preserved more intact. With the continuous improvement of medical imaging technology, the use of computer to measure and analyze three-dimensional skeletal images has become a trend of forensic anthropology research. Therefore, for individuals in central China, this study aims to establish a mathematical model for sex determination by using multiple measurement indexes of maxillary arch and evaluate its effect. Firstly, 21 indexes of 180 cases (83 males and 97 females) from central China were measured based on the cone beam CT samples of the maxillary arch. Then, the statistical software SPSS 20.0 was used to screen out indexes with gender differences. Finally, we analyzed the measured indexes with gender differences by single variable and multivariable discriminate analysis, and the mathematical model was obtained and the accuracy of the sex determination was calculated. The results showed that there were 10 indexes with statistical difference between male and female (P<0.05) among the 21 indexes, and the average value of male was greater than that of female. Univariate discriminant analysis was carried out on these 10 indexes, 10 discriminant formulas were established, and the accuracy rate was 57.2%－72.2% after cross-verification. Through cross validation, the accuracy of the upper dental arch width was the highest, up to 72.2%. The multivariable discriminant analysis showed that the accuracy rate of the discriminant formula obtained by direct method was 73.4% after cross-verification, and the accuracy rate of cross verification was 72.2% after the variables were selected by stepwise method, and the two variables of upper alveolar arch length and upper alveolar arch width were included in the discriminant analysis. The accuracy of direct method was higher than that of stepwise method. The study showed that the upper jaw arch measurement indexes in this study have a certain value for sex determination. In the next research, we will also explore the application value of more skull bone markers in various aspects of forensic anthropology.
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The DNATyperTM 21 kit has good species specificity, typing accuracy, and locus amplification balance, which can be used for forensic genetic analysis such as individual identification and paternity testing. To improve the anti-inhibitor ability of this kit, the addition of bovine serum albumin (BSA), bovine thrombin (BT), FastStart Taq DNA Polymerase, TaKaRa Ex Taq Hot Start Version (Ex Taq HS), MyFiTM DNA Polymerase, and Klentaq DNA Polymerase (Klentaq) as PCR enhancers to the PCR reaction system was explored in the presence of different concentrations of inhibitors, such as indigo, humic acid (HA), hemoglobin, heme, and melanin. The results revealed that BSA exhibited high efficiency in improving the detection rate of STR loci; BT only helped to overcome the typing inhibition caused by indigo, melanin, HA, and heme; Four types of DNA polymerase had different anti-inhibitor effects on different inhibitors, among which Ex Taq HS was more effective than the other three DNA polymerases, but displayed comparatively lower resistance to hemoglobin than BSA and BT. This study provides basic data for further optimization of the kit through comprehensive analysis and facilitates its application in daily forensic investigations.
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Through electron microprobe element analysis and electron backscatter diffraction analysis, a study was conducted on the micro-area element segregation and grain distribution morphology of aluminum and copper wire melting marks caused by fire and short circuits. The results showed significant iron element segregation in both fire-induced and short-circuit-induced melting marks of aluminum wires, but with different distribution patterns: iron elements formed coarse ring-like structures in fire-induced marks, while they appeared as elongated chain-like structures in short-circuit-induced marks. For copper wires, both fire-induced and short-circuit-induced melting marks exhibited oxygen element segregation, with distinct oxide morphologies: oxides in fire-induced marks were concentrated and mainly appeared as elongated rod-like or point-like structures, whereas in short-circuit-induced marks, they were dispersed and mainly spread in a network-like pattern. Additionally, there were notable differences in grain distribution and orientation between fire-induced and short-circuit-induced melting marks of both aluminum and copper wires. Fire-induced marks were dominated by coarse equiaxed grains or dendrite-like structures, while short-circuit-induced marks were mainly characterized by coarse columnar grains. It is worth noting that grain growth in short-circuit-induced marks exhibited a clear preferential orientation, whereas no such preference was observed in fire-induced marks.
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This article aims to construct and valuated a novel multiplex PCR system, which consists of 21 loci and is used to identify the parentage of horses. Applying fluorescent labeling technology, HTG06, HTG07, COR022, CA425, HTG04, COR082, LEX54, COR069, AHT05, HMS03, HMS01, HMS06, HMS07, COR058, HTG10, ASB17, VHL20, HMS02, ASB02 LEX34, Amelogenin, a total of 21 equine motifs, were subjected to primer design, PCR complex amplification and CE platform sequencing to verify the sensitivity, specificity and tolerance of the system. A total of 128 actual samples were tested and compared for genetic relationship. Among them, 66 samples with unknown genetic relationship were analyzed by polymorphism analysis. The complex amplification system was able to detect 128 equine samples to obtain complete STR typing, and in the actual amplification, no non-specific peaks were generated, and no specific amplification peaks appeared for different species of animals, such as bovine, sheep, pig, chicken, cat, dog and human DNA samples. 0.075 ng of equine standard could still obtain complete typing under 10 μL system. The tolerance of the four common inhibitors could reach 200 μmol/L for heme, 200 μmol/L for hemoglobin, 100 ng/μL for humic acid and 1.2 mmol/L for EDTA, respectively. The STR multiplex amplification system established in this study is effective and reliable, which can meet the needs of laboratory for the identification of paternity of horses.
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STR genotyping based on the traditional capillary electrophoresis technology focuses on length polymorphisms of the markers. Sequence differences among STR isometric alleles, such as SNPs and InDels, cannot be reported. Next-generation sequencing can report abundant sequence polymorphism information of STRs, including the repetitive sequence and non-repetitive interval sequence information in STR repeat regions, as well as sequence information in flanking regions, supporting forensic applications. This article reported a 21-year-long indoor homicide case. Genotypes for 38 Y-STRs were obtained by the traditional Y-STR detection method. Y-STR sequence information was reported by using the STRSeqTyperY68 kit and next-generation sequencing technology. The STRSeqTyperY68 kit genotypes fifty-two single-copy Y-STR loci, six two-copy Y-STRs, one three-copy Y-STR, and one sex determinant locus in a single reaction tube using the MiSeq FGx sequencing platform. Full sequence-based genotypes of 67 Y-STR markers were determined for one evidence collected from crime scene and eight reference samples. After comparing the 67 Y-STR genotyping result of the crime scene evidence with the eight reference samples, we found that the length-based genotypes at DYS448 were 20 among for all these nine samples. Their repeat structures were also consistent, which were the combination of 11 [AGAGAT] repeat units and 9 [AGAGAT] repeat units with a non-repetitive sequence of 42 nucleotides (N42) in the middle. However, the difference lied in the 32nd base of the “folded sequence” N42 of DYS448: scene evidence and sample 1 were C, while the other seven reference samples were T. Based on a single base substitution in the N42 ‘folded sequence’ of the DYS448 locus, the case was directed and key technological support was provided. This article further explored sequence variations in the N42 ‘folded sequence’ of DYS448 in different populations, as well as detailed information on loci with ‘folded sequence’ in the STRSeqTyperY68 kit, providing reference for related research and case applications.
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ENFSI has released a series of important documents, including Vision of the European Forensic Science Area 2030, ENFSI Strategic Plan 2023-2026, and ENFSI Action Plan 2023-2024, which collectively chart the future direction and strategy of forensicc science in Europe. The field of court science in Europe is facing the challenges and opportunities of emerging technologies, in particular the application of advanced technologies such as Artificial Intelligence, Big Data Management, aiming to improve the reliability and efficiency of court science outcomes. ENFSI is committed to promoting innovation and development of forensicc science in Europe by means of clear objectives and action plans. The development strategy of European forensic science has important inspiration for the progress of forensic science in China. Through in-depth understanding and drawing on the European experience, combined with the actual situation in China, we can formulate a more scientific and reasonable development path to promote China’s forensic science to a new height, and provide strong support for the construction of the rule of law and judicial justice.
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Five samples from a fourth-generation pedigree were tested and reviewed using three different reagent kits:ABI Yfiler Huaxia Platinum, AGCU Y SUPP Plus and SureID PathFinder Plus kit, Y-STR profiles were obtained for these samples. We observed that one of the samples exhibited different genotypes at four Y-STR loci (DYF387S1, DYS527, DYF404S1, and DYS459) when compared to the other four samples, and the maximum allelic difference was 11 steps. The other samples showed “two bands” at these loci, while this particular sample exhibited “one band.” This observation did not conform to the stepwise mutation model. Upon further examination of the Y-chromosome sequence-tagged sites for this sample, we detected a partial deletion (gr/gr) in the AZFc region of the Y chromosome. Based on the family inheritance structure analysis, we concluded that this partial deletion occurred during paternal transmission as a fragmentary deletion. Partial deletions in the AZFc region can result in inconsistencies between the genotyping of multicopy loci, such as DYF387S1, located in that region, and the genotyping of familial samples. This should be paid more attention in practical work. If necessary, Y-chromosome STS testing can be performed on the sample, providing a scientific basis for investigating Y-STR profiles in families.
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At present, in genetic identification, the detection of autosomal STR loci and the calculation of half sibling index using the ITO method can infer whether there is a genetic relationship among the identified individuals. However, the ITO method sometimes cannot provide a clear judgment basis for calculating likelihood rates. Therefore, multiple genetic markers can be detected to assist in judgment and different calculation methods can be used for comprehensive analysis to obtain evidence support for determining genetic relationships. Half sibling identification is a difficult point in genetic relationship identification, especially in heterosexual half sibling relationships, which cannot be assisted by the genetic rules of X-STR or Y-STR, which further increases the risk and difficulty of identification. In the case where only two individuals participate in identification, it is also impossible to analyze through family reconstruction methods. Therefore, in a case of half sibling relationship identification, this article detected genetic markers such as autosomal STR, mtDNA, and SNP, and comprehensively used various analysis methods such as ITO, discriminant function, mitochondrial high variability region polymorphism, and state consistency based on allele frequency estimation to infer the degree of kinship. Through mutual verification of multiple genetic marker detection results, reliable identification results were finally obtained.
