15 December 2021, Volume 46 Issue 6
    

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    Research Articles
  • Analysis into Functional Data of Spectral Images from Bloodstains of Human and Two Species of Animal
    HUANG Wei, GAO Linmei, GUO Wenwen, CUI Hengjian, LI Zhigang, XU Xiaojing, WANG Guiqiang
    Forensic Science And Technology. 2021, 46(6): 551-558. https://doi.org/10.16467/j.1008-3650.2021.0055
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    Objective Bloodstains, among the most commonly biological evidential materials found and extracted at crime scenes, are capable of providing clues and evidential proof for crime investigation. Hyperspectral imaging technology has presently been attracting attentions of many scholars and forensic professionals. This paper tried to study the ability of spectral imaging technology to reveal and distinguish human bloodstains from the animal's with both the field investigation and laboratory examination. Methods Bloodstains of human and two animals (chicken, snake) were separately made on each of four substrates (black/blue cloth and black/red leather), having their individual image collected. Each collected image was extracted of its spectral values that were converted into functional data and then analyzed with: 1) principal component analysis for quantitative determination of the bands where the three bloodstains' spectra were mainly concentrated into difference; 2) cluster analysis into the scores of principal components; 3) Fisher discriminant analysis for species classification. Results The principal component analysis showed that the first and second principal components contributed more than 96% of the related spectral information throughout the four substrate-harbored samples, demonstrating its ability to identify different bloodstains. Fisher discriminant analysis verified that the three species' bloodstains had been indeed discriminated accurately with the two principal components, rendering a discrimination accuracy of respective 96.6%, 98.8%, 99.0% and 94.6% for the three species' bloodstains on four substrates. Conclusions It is effective to distinguish human bloodstains from the animal's through spectral imaging data and their functional conversion. The spectral imaging technology and functional data analysis are feasible as choice for bloodstains to have their species identified.
  • Fe3O4@Tb-BTC: Preparation and Applicability for Latent Fingerprint Development
    LIU Jiayang, LIU Weicen, ZHANG Sai, LIU Li
    Forensic Science And Technology. 2021, 46(6): 559-565. https://doi.org/10.16467/j.1008-3650.2021.0108
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    Objective To prepare Fe3O4@Tb-BTC nanoparticles (a kind of magnetic nanomaterials) with Fe3O4 (one ready prepared nanoparticle) as the core and Tb-BTC as the shell for detecting their applicability to develop latent fingerprints. Methods The Fe3O4@Tb-BTC magnetic nanomaterial was synthesized through a certain procedure that Fe3O4 nanoparticle was successively added with Tb(NO3)3 and H3BTC plus other necessary treatments, having been characterized through transmission electron microscope (TEM) and X-ray diffraction (XRD) so that its properties had been explored. Such the magnetic nanomaterial product (Fe3O4@Tb-BTC powder) was adopted to develop the sebum-resulted fingerprints on either the permeable or non-permeable or semi-permeable objects. Further, the Fe3O4@Tb-BTC powder was probed into its developing effect on latent sebum-resulted fingerprints that were left over for different time (1, 3, 5, and 7 days) or come into being from same-finger's 5 consecutive pressing. Comparison was carried out into the latent-fingerprint developing applicability between the Fe3O4@Tb-BTC approach and the ordinary method of magnetic fluorescent powder. Results The prepared Fe3O4@Tb-BTC nanomaterial is of uniform size and stable properties, demonstrating good effect about developing sebum-resulted fingerprints on a variety of objects, having nearly not been influenced with the fingerprints' left-over time and the amount of sebum deposited (as to the verified time and remnant). Bright green fluorescence was emitted from the Fe3O4@Tb-BTC-unveiled fingerprints on excitation under 254nm ultraviolet light, revealing a better developing effect than that from the ordinary magnetic fluorescent powder. Conclusions This method can effectively develop sebum-resulted fingerprints on various objects, able to greatly enhance the contrast of fingerprints and reduce the interference from background, hence demonstrating extremely high application prospect and value.
  • Devising Software Enabling Automatic Discrimination between Menstrual and Peripheral Blood Based on miRNA Relative Expressions
    WANG Guoli, LIU Yang, HE Hongxia, JI Anquan, ZHANG Wei, CAO Yang, SUN Qifan
    Forensic Science And Technology. 2021, 46(6): 566-572. https://doi.org/10.16467/j.1008-3650.2021.0029
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    Objective To explore the optimal combination of miRNA markers and classification model for effectively distinguishing menstrual from peripheral blood so as to build up one piece of simple and fast automatic discriminant software. Methods 10 kinds of miRNAs (miR-451a, miR-205-5p, miR-203a-3p, miR-214-3p, miR-144-3p, miR-144-5p, miR-654-5p, miR-888-5p, miR-891a-5p, miR-124-3p) were analyzed through quantitative real-time PCR into their relative expression quantities from menstrual (104 pieces) and peripheral (136 pieces) blood samples. Seven algorithmic models (kernel density estimation, K-nearest neighbor, logistic regression, linear discriminant analysis, supportive vector machine, neural network, random forest) were used for data analysis so that both the optimal miRNA marker combinations and appropriate algorithmic models were selected. Consequently, the software was therewith to construct for automatically distinguishing menstrual from peripheral blood with better identification effect. Results Three miRNAs of miR-205-5p, miR-203a-3p and miR-214-3p were of greatest difference between menstrual and peripheral blood, hence coming forth the better/optimal combinations of one or two of them assembling with miR-144-5p. Among the optimal combinations, the recommended one of miR-144-5p, miR-203a-3p and miR-205-5p demonstrated most robust. The appropriate classification model was the kernel density estimation for all the seven algorithmic ones, with the logistic regression being followed. Conclusions The automatic discriminant software constructed in this study is of friendly interface, simple use, accurate and reliable server algorithm, suiting for assisting forensic calculation on menstrual and peripheral blood identification, therefore capable of effectively facilitating the forensic analysis of evidential materials and great value of promotion and application.
  • Distribution and Metabolic Pathway of Flualprazolam in Rat
    CAI Yugang, WU Yongfu, ZOU Bo, WANG Wen, HUANG Xujin, ZHANG Lian, CHANG Jing, DAI Yong
    Forensic Science And Technology. 2021, 46(6): 573-579. https://doi.org/10.16467/j.1008-3650.2021.0085
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    Objective To probe into the distribution and metabolic pathway of flualprazolam plus its main metabolite (α - hydroxylflualprazolam) in rat. Methods 40 SD rats were randomly divided into 4 groups and fasted for 12 hours, with the first group being fed of flualprazolam by gavage as per 0.45 mg/kg and having their respective blood collected from tail vein at different time and each one's urine received every day after administration. The second group was taken as the blank control to the first one. The third group was executed at 0.25h after drug administration, having their respective blood, heart, liver, lung, kidney, brain, spleen and muscle collected and extracted with rapid solvent extraction. The fourth group was the blank control against the third one. The distributing and metabolizing flualprazolam and α - hydroxyflualprazolam were detected through HPLC-MS/MS. Results Flualprazolam was found of rapid distributing and metabolizing in rats, reaching its highest blood concentration within 0.25h, having shown its sequential distribution in various organs as follows: kidney > brain > heart > liver > spleen > muscle > muscle > lung > blood. Yet, α - hydroxyflualprazolam demonstrated its discrepant organ-specific distributing order: liver > kidney > heart > spleen > lung > muscle > blood > brain. Conclusion The experiment has showed the distribution and degradation of flualprazolam and its main metabolite in rats who were administered of flualprazolam by gavage, capable of providing scientific basis for flualprazolam to test in vivo and have its metabolic pathway analyzed.
  • Impact of Image Super-resolution Technology on Comparison of Personal Image
    HOU Xinyu, XIE Lanchi, LI Zhigang, LI Zhihui, HUANG Wei, WANG Lei
    Forensic Science And Technology. 2021, 46(6): 580-586. https://doi.org/10.16467/j.1008-3650.2021.0111
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    Objective Through coalescence into deep learning, image super-resolution technology is being paid of attention for forensic personal imaging. Thus, a trial was here to carry out about the impact of image super-resolution technology on comparison of personal photographs from cases or events. Methods With 94 sets of sampling personal photographs collected from real cases, grouping was made on their respective quality-different image so that two image super-resolution algorithms were adopted to enhance the image of personal photograph. Such resultant image was compared against its original photograph image at 1:1 (or N) contraposition under different preset conditions, hence having brought forth the intrinsic alternation of causation. Results Comparison results showed that the image super-resolution technology is not universal for improvement of image, demonstrating that it is not so good to improve the low and medium quality images as the sharpening processing, leaving the high quality image being improved significantly yet less practical applicability. Nevertheless, the image super-resolution technology is able to render a good improvement into an individual image. Conclusions From this analysis, the image super-resolution technology is referential for forensic personal image to utilize practically, yet not be over-relied on.
  • Evaluation on Quality of Voices Recorded from Testing into Different Mobile Phones and Telecom Networks
    SHEN Xiaohu, JIN Tian, WANG Lei, HAN Chaoyang
    Forensic Science And Technology. 2021, 46(6): 587-593. https://doi.org/10.16467/j.1008-3650.2021.0158
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    Objective To provide a theoretical basis for examination of mobile phone's recording quality that is important for correct opinion to deliver in the forensic voiceprint identification of voice samples from the ubiquitous mobile phone calls. Methods A quantitative standard was proposed for evaluation of the recorded samples that were obtained from the tested mobile phones and generation-various telecom networks. The standard, rooting on the basis of mainstream identification equipment, was analyzed into the quantity and digital values of formant in voiceprint spectrogram, fundamental frequency parameters, regional average spectrum and implemented voiceprint comparison test. Results The test results showed that certain differences existed with the recording quality under different conditions, having caused definite influence on voiceprint identification, yet at a non-essential extent. Conclusion For voice identity authentication, the influence should be considered of recording quality differences on identification of the recorded samples from different mobile phones and telecom networks, therewith evaluated and overcome during identification.
  • UPLC-Q/eOrbitrap HRMS Determining Alcohol Biomarkers in Bloodstains
    LIN Dawei, ZHANG Yunfeng, ZHENG Jiajia, LI Wenhai, RAO Yulan, LI Xiuyun, SUN Honglei, SHAO Kai, XIA Qingbing
    Forensic Science And Technology. 2021, 46(6): 594-599. https://doi.org/10.16467/j.1008-3650.2021.0086
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    Objective To establish a method for determination of two alcohol biomarkers (ethyl glucuronide, EtG; ethyl sulphate, EtS) in bloodstains via ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UPLC-Q/eOrbitrap HRMS). Methods The bloodstains were prepared on clean glass slide where to have dropped the venous blood spiked of EtG or EtS, having them extracted with 50% hydrated methanol. The bloodstain-extracted supernatant was separated on a Synicronis C18 column (150mm×2.1mm×5.0μm) with gradient elution that was run through the mobile phases consisting of 0.1% formic acid (phase A) and acetonitrile : methanol (v/v 1:1) (containing 0.1% formic acid ) (phase B). MS tests were coupled with HPLC under HESI (heating electrospray ionization) source operated in negative ionization full-scan mode. Results Both EtG and EtS were linear with their calibration curves among the range of 0.2-100ng/patch (R2=0.9991, 0.9994), showing good recovery, intra- and inter-day precision less than 15%. The matrix effect was in the range of 85%-120%. Conclusion The method is effective to detect alcohol biomarkers (EtG and EtS) in bloodstains.
  • Forensic Comparison into Image Acquisition from Rainbow Holograms on Prints
    LIAN Zhe, SHI Gaojun, LIANG Luning, YANG Ruiqin
    Forensic Science And Technology. 2021, 46(6): 600-604. https://doi.org/10.16467/j.1008-3650.2021.0022
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    Rainbow hologram is at present widely used in commodity packaging, anti-counterfeiting with both the currency and certificate. However, some counterfeiters are also able to fabricate holographic patterns into their purposed prints of fake goods. Thus, a correlative forensic comparison is required to identify the authenticity of the involving samples and track their sources when the related rainbow holograms are suspicious of genuineness or becoming the crucial evidential item. Integrated into real cases, this paper compared the power of document examination workstation (VSC6000) and laser holographic identification instrument (Regula 2303) to discriminate the rainbow holographic patterns printed on genuine and counterfeit commodities and/or currencies. Consequently, a universal method was established about forensic comparison into image acquisition from rainbow hologram, demonstrating effective for forensic identification with the tested results. Additionally, discussions were made about the relevant technological problems, with the feasibility and applicability being illustrated of concatenating cases and tracking the sources of counterfeits.
  • Distinguishing Papers of Embedding Security Thread with Relevant Morphological Features
    LI Zhihao, LI Peng, LIN Leixiang, GUANG Xiaoli, YUAN Mingjun, HU Kun, ZOU Jixin
    Forensic Science And Technology. 2021, 46(6): 605-609. https://doi.org/10.16467/j.1008-3650.2021.0159
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    Objective To distinguish the papers embedded of security thread with which to have the formation method based so that the papers commonly used for counterfeit banknotes were to classify through analysis of the thread's morphological characteristics, with purpose to provide a new technical means for counterfeit banknotes to have them concatenated and traced into source. Methods The papers of embedding security thread were observed and analyzed with VSC6000 comparator, electronic microscope and energy dispersive spectrometer (EDS), successfully having their embedding security threads delved and known into the morphological features. Consequently, the papers were to classify on the basis of characteristic formation of the security threads. Results The security threads of the tested papers are of three types: composite, concave and convex. Conclusion The papers used for counterfeit banknotes could be classified and determined of their source from the morphological features of those relevant embedded security threads, hence could play a crucial role in concatenating cases, tracing sources and precisely attacking crimes of counterfeit banknote.
  • Comparative Analysis into Composition of Bullet and Shell from Cartridge
    YANG Anan, YANG Ruiqin, GUO Hongling
    Forensic Science And Technology. 2021, 46(6): 610-613. https://doi.org/10.16467/j.1008-3650.2021.0160
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    Objective Evidential cartridges can provide scientific basis with their chemical composition analysis into the investigation of gun-related cases. Therefore, an experiment is here to carry out for quickly distinguishing different bullets and providing key information on inferring discrepant bullets through the element composition of sampling cartridges to probe. Methods 53 producer-different and specification-various sampling cartridges were collected with their manufacuring at the unlike batches during 1958~2019. Major element composition was to determine into the different components (i.e., lead core inside bullet, bullet jacket and cartridge case) of the sampling cartridges, delivering results through the test with scanning electron microscopy and energy dispersive X-ray (SEM-EDX). Results Most bullets were shown of made of pure lead, with some of later-produced batches being of lead-antimony alloy, two earlier-produced batches of iron warhead. Although there were no obvious regular features for either the jackets of six 5.6mm sporting rifle's cartridges or the shells of four samples made from factory 791, all the other analyzed jackets and shells were made with three types of Cu/Zn alloy, revealing the Cu content ranging between 83.7%-84.7%, 87.6%-90.6% and 67.0%-69.8%, respectively. The materials used in the jacket and shell from the model- and manufacturer-same samples remained consistent over time, contrasting to the significant differences with both the model-same yet manufacturer-different samples and the model-different yet manufacturer-same ones. Over the past 60 years, the samples produced from factory 121 had their bullet jacket and shell both made of Cu/Zn alloy, with the Cu accounting for 87.6%-90.6% of jacket and 67.0-69.8% of shell, suggesting that these two types of Cu/Zn alloy were the common raw materials used with the factory. Four shells of sampling cartridges produced from factory 791 were made of Fe/Mn alloy with Mn accounting for 0.7-0.9%, however, the other manufacturers selected for this experiment hadn't been found to adopt the Fe/Mn alloy. Conclusion Element composition and analysis can be used as choice to identify the kind of bullets through determination of the materials of their components.
    • Reviews
  • Impartation-purposed Review on Research Progress of Trace Evidence about Its Transfer Regularity and Persistence
    SUN Zhenwen, SHI Yi, QIAO Ting, ZHANG Guannan, LIU Zhanfang, WANG Ping, PENG Silu, ZHU Jun
    Forensic Science And Technology. 2021, 46(6): 614-620. https://doi.org/10.16467/j.1008-3650.2021.0032
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    Forensic trace evidence is very important for the involved case to be solved with the supportive proof from evidential materials of, e.g., fiber, paint and gunshot residue (GSR). Following to Locard's exchange principle, often quoted as “every contact leaves a trail”, trace evidence is characteristic of transferrability, universality and potentiality. Therefore, trace evidence can provide either direct proof/clue or essential item in the evidential chain. In recent years, the development of analytical instruments has brought forth the prominent specialty of trace evidence, having gradually expanded the scope of relevant examination, together with the technical methods being continued to improve. Consequently, a large number of studies have been carried out on trace evidence about its transfer, persistence, discovery, collection and examination home and abroad, presenting not only pertinent guidance to recover and collect the trace evidence at crime scene but also a basis for the evidence to interpret, reconstruct into the scene and depict the suspect. Summarization was here made with trace evidence about its research progress on transfer and persistence, briefly introducing the secondary transfer and influential factors for persistence. Furthermore, discussions were thereby put forward into the impartation of related researches on the examination and application of forensic trace evidence in China, aiming to provide reference for trace evidence to target collection and utilization in improving its evidence value into actual cases.
  • Prospect on Raman Spectroscopy to Apply into Examining Exit-entry Travel Documents
    WANG Shenhan, HAN Ying, DU Peng, JIANG Yangyang
    Forensic Science And Technology. 2021, 46(6): 621-628. https://doi.org/10.16467/j.1008-3650.2021.0140
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    Exit-entry travel documents are the official documents for citizens to exit and enter their own country and travel abroad, therefore maintaining important role for management of both immigration and exit-entry. The accuracy of examining these documents directly affects the security of border and society. With continuously updating their forgery means, the crime-relevant offenders have ever been counterfeiting such documents that are too quasi-genuine to identify their authenticity with traditional visual and/or physical inspection. Component analysis is going to become the technological trend for examination of Exit-entry travel document. Raman spectrum, known as the molecular fingerprint about material component, is an effective tool for material identification with its advantages of, e.g., non-destructiveness, micro region of detection, rapidity and simplicity. Based on the material composition analysis of exit-entry travel document, the application of Raman spectroscopy was here reviewed in relations to paper, ink, seal and fiber, together with discussions on the possibility and prospect of Raman spectroscopy to apply into examination of exit-entry travel document from the perspectives of prevention against counterfeits from material, printing, binding and issuance. Besides, the attentions were suggestively paid about potential problems and developing trend about the technology to apply into document identification. For chemical composition analysis to promote into material identification of certificate/document, further and wider researches should be developed to solve the challenges with certificate/document examination.
  • Research Progress of Selegiline and Its Metabolite R-methamphetamine in Biological Samples
    YU Zhe, REN Xinxin, WANG Aihua, DI Yumin, ZOU Bo, WANG Ruihua, ZHANG Yunfeng, CHANG Jing, YU Zhongshan
    Forensic Science And Technology. 2021, 46(6): 629-634. https://doi.org/10.16467/j.1008-3650.2021.0073
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    Selegiline, a drug for treatment of Parkinson's syndrome, can metabolize into methamphetamine in vivo. With the effectual functions to inhibit the activity of monoamine oxidase and increase the concentration of dopamine, selegiline plays its role into alleviating Parkinson's symptoms of the involved patients. Commonly, selegiline will metabolize into R(-)-methamphetamine, R(-)-amphetamine, desmethylselegiline and other substances alike in vivo. Both selegiline and its metabolites have a left-handed chiral structure such a reliable sign that can be utilized to detect whether some methamphetamine is abused or derived from official administration of selegiline. This article reviews the research progress of selegiline about its functional mechanism, metabolites and detection methods for forensic toxicology. Determination of selegiline usually carries out with gas chromatography, liquid chromatography and related techniques. Actually, there have been forensic actual cases that adopted relevant testing methods to determine whether they were of normal selegiline usage or abusing methamphetamine. Besides, selegiline and metabolites are also able to play their role into estimating the use of illicit drugs in cities (or certain areas), capable of determining whether methamphetamine is abused or from the various metabolites of selegiline. The future forensic toxicological researches and identification should pay attentions to the discrepancy, to the influence of other biological materials on test results, and to exploration into available detection techniques about selegiline quantitative analysis.
    • Research and Discussion
  • Bibliometric Analysis of Fingerprint Researches with Publications from Forensic Science and Technology during 2011 to 2020
    CAO Jiming
    Forensic Science And Technology. 2021, 46(6): 635-641. https://doi.org/10.16467/j.1008-3650.2021.0143
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    Objective To survey the basic situation of fingerprint researches with publications from the journal of Forensic Science and Technology during 2011 to 2020, so as to further explore and understand the progressing trend of dactylography. Methods Bibliometric paradigm was here conformed to make a statistical analysis on fingerprint researches published in Forensic Science and Technology during the period of 2011-2020 about their output status, relevant institutions, main authors, highly-cited papers, distribution of funds and academic research hotspots. Results In the period designated with this survey, there were 197 papers on fingerprint researches published in Forensic Science and Technology, accounting for 12% of total number of published papers, with 149 ones as the co-authored thus rendering a co-authorship rate of 75.63% and cooperation degree of 2.73. There were 58 papers shown of supporting with various funds from 98 items/times, accounting for 29.44% of all the published papers. Both Institute of Forensic Science of Ministry of Public Security and People's Public Security University of China were the quantity-highest contributors of papers, each having delivered more than 30 articles. Seven of the top 10 cited articles were from People's Public Security University of China who was also the owner of most cited and downloaded papers. For principal research themes, the main focus was found on basic dactylography mining, fingerprint development and extraction, automatic fingerprint identification plus fingerprint examination and identification, demonstrating each respective published papers as 13, 98, 10 and 49 ones. Conclusions During the designated period (2011-2020), the overall quality of fingerprint researching papers published in Forensic Science and Technology had been continuously improved. After 2016, the number of papers supported with various funds had increased significantly, so had the number of high-quality papers funded with nation and/or Ministry of Public Security. Both Institute of Forensic Science of Ministry of Public Security and People's Public Security University of China were the leaders of fingerprint researching. Obviously, fingerprint researches were going to focalize their developing trend and hotspots on the third level characteristics of fingerprint, new development and extraction technology, automatic fingerprint identification system and examination/identification of difficult-to-handle fingerprints.
  • Exploration into Essentials about Checking Procreation Ways of Audio Files Saved with “Voice Memo” APP under IOS
    ZHOU Juan, YI Shuang
    Forensic Science And Technology. 2021, 46(6): 642-646. https://doi.org/10.16467/j.1008-3650.2021.0109
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    Objective To explore the procreation ways of audio files stored with “voice memo” APP under IOS of iPhone or iPad. Methods Experiments were tried on the “voice memo” functions from model-various iPhone or iPad devices, having been undertaken of such functional operations as recording, clipping, sharing, saving, replacing and modifying file names so that the relevant metadata and tail information were generated into the resultant audio files. Comparisons were carried out among the resulted information so as to seek their procreation ways. Through contrasting both the metadata and tail information from the audio files that were transferred and dumped between the apps of “voice memo” and “wechat” and “file”, how these information contents were conveyed and delivered was explored. Results Both the metadata and tail information showed regular discrepancy among the resultant audio files if different functional operations of “voice memo” were adopted into an audio file. Similar regularity of alteration was also found when audio files were transferred and dumped between the apps of “voice memo” and “wechat” and “file”. Conclusion An audio file can be judged of its procreation way with examination into its metadata and tail information from the “voice memo”.
  • Influence of Placement Time on Identification of Combustion Residues of Alkyd Paint Thinners
    HE Fenfen, JIANG Guangxin, JIN Jing, LIU Ling, LIN Qingwen
    Forensic Science And Technology. 2021, 46(6): 647-651. https://doi.org/10.16467/j.1008-3650.2021.0161
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    Objective To probe into the changes of characteristic components of combustion residues from alkyd paint thinners under different durations of placement. Methods The alkyd paint thinner (X-6), selected as the research object, was imbibed into absorbent cottons (as the carrier) that were afterwards ignited and burnt for certain durations before extinguishment, having such resultant combustion residues left and stored for 0, 3, 5, 7 and 9 days, respectively. GC-MS was to analyze the variation of characteristic components of the combustion residues under different durations of storage. Results The original sampling alkyd paint thinner mainly contains aromatic hydrocarbons and alkanes. Alkanes were found of no appearance in the combustion residues while new substances, e.g., thick cyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and ninhydrin, were detected within 5 days, yet PAHs were unable to be detected after 7 days and ethyl benzene was the only left one of aromatic hydrocarbons after 9 days. Thus, the list of target compounds allowed inclusion of tritoluene, phenanthrene, fluoranthene and pyrene. Both tritoluene and indene were revealed of their contents not affected with the storage time, whereas polycyclic aromatic hydrocarbons even increased their contents. Conclusions For actual fire investigation and identification of the related material evidence, the alkyd paint thinner should be detected within 5 days, and timely extracted and delivered for examination.
    • Technology and Application
  • Forensic SNP Genealogical Inference Helping Ferret out a 14-year-long Unsolved Cold Case
    LIU Jing, MA Mi, WEI Yiliang, LI Yingxiang, JIANG Li, WANG Guiqiang, YE Jian, JI Anquan, LI Caixia
    Forensic Science And Technology. 2021, 46(6): 652-656. https://doi.org/10.16467/j.1008-3650.2021.0028
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    Y-STR familial screening is at present an important resort for investigating male suspects with forensic DNA cases. However, the same paternal lineage may maintain the similar or identical Y-STR genotype for several or even dozens of generations, resulting in eligible matches falling into multiple paternal families in different regions nationwide. Nevertheless, Y-STR is incapable of analyzing the distance of kinship between all matched families and the suspect so that the relevant local police will be difficult to determine the target family because investigating all the matched families is both time-consuming and waste of resources. Recently, a SNP genealogy inference technology has been developed with Institute of Forensic Science, Ministry of Public Security, able to predict genetic kinship boastfully from 1st- to 7th- generation tiers through the genome-wide SNP data. As thus, such a technology, combined with the ancestry inference, was applied to investigating into a 14-year-long unsolved cold case of rape and murder, having assisted the local police to successfully determine the biogeography and family information of the suspect so as to provide key technical support for the case to resolve.
  • Elevated Concentration of Postmortem Blood Cadmium yet not Death Cause
    WANG Aihua, YU Zhongshan, LIU Xingsheng, ZHANG Yunfeng, WANG Ruihua, Ren Xinxin, ZOU Bo, HOU Xiaoping, CHANG Jing
    Forensic Science And Technology. 2021, 46(6): 657-660. https://doi.org/10.16467/j.1008-3650.2021.0080
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    Two cases were here reported about abnormal elevation of cadmium concentration in postmortem heart blood of victims who died from non-cadmium poisoning. One dead showed her heart blood was 200-fold higher of cadmium concentration than the upper limit of healthy living people, with the other one demonstrating his 40-fold higher. The autopsy also revealed that different body parts were of discrepant blood cadmium concentration, with tissues being within normal range. Observations were further made about cadmium concentration in venous blood from 100 living people and heart blood from 50 non-cadmium poisoning victims. It was found that the 100 living people were all less than 5ng/mL of cadmium concentration in venous blood, and the 50 non-cadmium poisoning victims had the raised heart cadmium concentrations. There were 20% samples appearing their postmortem blood cadmium concentrations rose to 10 times more than the upper limit of normal, with some even reaching up to nearly 100 times higher. The elevated cadmium concentration of postmortem blood may result from the postmortem redistribution and diffusion of cadmium stored in tissues, e.g., liver, kidney. Thus, a suggestion should be here put that postmortem blood cadmium concentration must be not taken as the only diagnostic indicator for identifying cadmium poisoning but combined with other sample tests and life track survey.

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