15 February 2021, Volume 46 Issue 1
    

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    Research Articles
  • Image De-noising Manipulation through Twice BEMD Coalesced with Wiener Filtering
    HOU Xinyu, XIE Lanchi, HUANG Yanming, YAN Yuwen, XU Lei, WANG Lei, LI Zhihui
    Forensic Science And Technology. 2021, 46(1): 1-7. https://doi.org/10.16467/j.1008-3650.2021.0001
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    Objective To put forth an idea about image de-noising through the coalescence of Bidimensional Empirical Mode Decomposition (BEMD) and Wiener filtering manipulation, with the resultant effect being verified. Methods One noise-bearing image was disintegrated with the BEMD handling so that the resultant first two-order noise-bearing componential portions of the image were extracted to de-noise with Wiener filtering. Both the BEMD disintegration and Wiener filtering were performed once again into the de-noised two-order componential portions that had been dismantled out from the preceding manipulation, thereby making the noise borne into the image removed one more time. Finally, all the resultant de-noised componential portions were retroactively combined with the intact remainders of the image, hence coming into being the new image of effectual de-noising. With comparison against the conventional disposal choices, the manipulation adopted here was verified of its feasibility and robustness. Results The post-manipulation image demonstrated that such the processing here can not only effectively reduce the noise from image but also maintain the image information well. Conclusion The image de-noising manipulation introduced here is novel and effective, having good reference and applicability in forensic image processing.
  • Correlativity between Sequencing Depth of Next Generation Sequencing and Its Resulting Accuracy for Forensic STR Genotyping
    WANG Ziqi, WU Bo, CHEN Man, FENG Yaosen, ZHANG Chi, LI Mingguang, KANG Kelai, NIE Shengjie, WANG Le, WU Jian
    Forensic Science And Technology. 2021, 46(1): 8-15. https://doi.org/10.16467/j.1008-3650.2021.0002
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    Objective To assess the correlation between sequencing depth of next generation sequencing (NGS) and its resulting accuracy for forensic STR genotyping. Methods Commercial products of genomic DNA were selected to prepare single-sourced and mixed DNA samples. The targeted STR-fragment amplification was carried out with a kit of 25-plex early access STR panel from Thermo Fisher Scientific, therewith having four libraries resulted through each amplification product and different barcode adapters. The amount of libraries, linked with each barcode adapter, was controlled to respectively occupy 1/4, 1/8, 1/16 and 1/32 of one Ion 318 chip. The pooled libraries were sequenced on an Ion PGMTM machine, with the sequencing data being analyzed by way of the Ion Torrent SuiteTM software. Meanwhile, deep exploration was conducted into a dataset of 6928 sequences representing alleles, stutters and noises that were harvested from 95 unrelated Chinese Han-ethnic individuals who were the subjects of one project accomplished and reported by Pang Jingbo et al using the same kits and sequencer as this work. Thus, the NGS sequencing depth was correlatively probed with the accuracy of STR genotyping. Results The sequencing depths of each STR locus decreased significantly with the declining amounts of loaded libraries. For single-sourced samples, full genotyping profiles can be obtained when no more than 8 normalized libraries were loaded to a single chip. For mixed DNA samples at a ratio of 1:20, no dropout allele was observed from the minor contributor when no more than 4 normalized libraries were sequenced on one chip. Sequencing depth statistics showed that the co-amplification system was not balanced among STR loci, suggesting the necessity of setting an analysis threshold for each locus. Conclusions Sequencing depth closely correlates with the accuracy of forensic STR genotyping. For each locus, the ratio of minimum sequencing depth to the average can be an important indicator for setting an analysis threshold. The number of libraries loaded to a single chip depends on the available kits, machines and experimental procedures with all of which are yet applicable for the same or similar task to get reference and suggestions from this work.
  • Analysis of Fake Videos Generated with AI-manipulated Replacement of Face Image
    WANG Yi, YANG Hongchen
    Forensic Science And Technology. 2021, 46(1): 16-22. https://doi.org/10.16467/j.1008-3650.2021.0003
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    Cyber deep learning technology is progressing so that Deepfake, one most influential facial editing software, gets plenty of substantial applications for manipulation. Such a face-swapping artifice combines the image tampering with AI (artificial intelligence) innovation, able to replace one video face with another under no change of the expression, movement and background of the original character. Deepfake has greatly reduced the difficulty to tamper facial images, resulting in numerous fake videos appearing. Consequently, crimes are increasingly involved with these affairs on/off networks. With introduction to Deepfake at the beginning, this paper elucidated about the relevant technologies on their context and development, carrying on the literature-based summarization, illustrating Deepfake from its basic framework, kernel structures to basic course and steps of video facial replacement, explaining the principle on how to drill and transform the facial images through autoencoding the built-in neural network into improving the generated image’s quality with the modified Autoencoder Network combined of GAN (generative adversarial nets). Finally, the comparison was made between the fake and original videos from five aspects: basic information, video editing signs, inconformity against the photographic routines and norms, video-audio contradiction, image identification and case truth, having disclosed the problems caused or existing in the fake videos. Malicious fake videos produced from Deepfake certainly pose potential threats to national security, social stability and personal privacy. Therefore, this paper may provide some theoretical support and practical reference for examining whether one video is real or fake.
  • Sino-overseas Forensic Science Branches Compared of Their Classification and Expression of Identification Scope
    GAO Junwei, WANG Yanbin, LU Yang, MU Jun, FENG Tao
    Forensic Science And Technology. 2021, 46(1): 23-28. https://doi.org/10.16467/j.1008-3650.2021.0004
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    Forensic science branches require to be classified into their appropriate scope. Such a task has always been being carried out scientifically and effectively so that the expression of relevant identification scope is on the way of unification and standardizing. Accordingly, assistance could be therewith provided to establish a complete standardization system of forensic expertise; guidance could be offered for forensic institutions to reasonably plan their organizational setup and accurately orient development direction; standardized administration could be supported with the competent governmental authorities. The comparison of Sino-overseas classification and expression of identification scope about forensic science branches is among the foundations to make the related task achieved better. Yet, China classification methods in forensic science are expected to be further unified, with some items of foreign methods being not included and differences existing between their expressions of identification scope. This paper made a Sino-overseas comparative analysis about forensic science branches of their classification and expression of identification scope, illustrating the practice and operations with the administrative organizations and international authoritative accreditation institutions, parsing the mentioned specifics and discrepancies. Therefore, suggestions are assuredly put forward that national standards should be formulated on classification of China forensic science, classification coverage expanded, and the expressed items/contents of eligible identification scope adjusted timely.
  • Effect of Image Denoising and Enhancement on Performance of Face Recognition System
    ZENG Jinhua, QIU Xiulian, BIAN Xinwei, SHI Shaopei
    Forensic Science And Technology. 2021, 46(1): 29-34. https://doi.org/10.16467/j.1008-3650.2021.0005
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    Objective Face recognition system (FRS) is favorite with public security because it can bring forth direct and visible facial images about the involving people. Therefore, the quality of face image is crucial for FRS to play its role effectively. Adoption of image denoising and enhancement can improve image quality, ever becoming the trend those eligible operators pursue. What effect does such an adoption have on the performance of FRS? This study is to explore into the question, with purpose to provide theoretical and technical reference for the selection of image processing approaches to apply FRS into forensic human image identification. Methods Face image materials were collected from 33 real cases about forensic identification of human images. Image denoising was carried out with Gaussian filtering and wavelet transform handling. Single-frame image super-resolution boosting, incorporated with the characteristics of edge-preserving and wavelet transform, was chosen for image enhancement. All the image processing choices adopted above were statistically analyzed to quantitatively assess their effects on the face recognition. Results Two image denoising methods (Gaussian filtering and wavelet transform) did improve the recognizing precision of FRS. However, the image enhancement technique (single-frame image super-resolution boosting) had no positive effect on the discriminability of FRS although it meliorated the displaying effect of the selected facial images. Among the image denoising means, Gaussian filtering, albeit simple of handling, brought the maximal improved performance into FRS. Conclusions Face image quality is of significant influence on the performance of FRS. The image processing could enhance the quality of face image, thereby capable of improving the recognizing precision of FRS. The image denoising methods utilized here could significantly enhance the performance of FRS, with Gaussian filtering being more suitable for improving the performance.
  • Pathway of Distribution and Metabolism of 2′-Diclazepam with Dosed Rats
    ZHOU Dajiang, CAI Yugang, WU Yongfu, ZOU Bo, HUANG Xujin, CHANG Jing
    Forensic Science And Technology. 2021, 46(1): 35-39. https://doi.org/10.16467/j.1008-3650.2021.0006
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    Objective To probe into the distribution and metabolism of 2′-diclazepam plus its metabolites (delorazepam, lormetazepam, lorazepam) with the dosed rats so as to provide reference data for the 2′-diclazepam-related cases. Methods 40 SD rats were randomly divided into 4 groups, leaving in fast for 12 hours, afterwards administered of 2′-diclazepam with two groups via gavage as per 2.625 mg/kg. Each rat of one group was collected of blood from the tail vein at different time after administration. Every member of another group was executed at 30 minutes elapsed from dosing, having its heart, liver, lung, kidney, brain and testicle collected to extract with ethyl acetate. The rest two groups were the blank controlling groups for the dosed groups, having the same destiny as their dosing counterpart. The bloods and extracts from the experimental rats were detected of 2′-diclazepam plus its metabolites with HPLC-MS/MS. Results 2′-diclazepam was rapidly distributed into rat tissues and metabolized, attaining its highest blood concentration within 20 minutes, demonstrating the discrepant distribution characteristics in various organs along with its metabolites as follows: liver > brain > heart > kidney > testicle > lung. Conclusion The pathway of distribution and metabolism of 2′-diclazepam plus its metabolites can provide reference with the gavage-dosed rats, bringing out the data valuable for identification of 2′-diclazepam related cases.
  • ZnS and ZnS:Cu Inorganic Ultraviolet Fluorescent Materials: Preparation and Developability into Sweat Latent Fingermarks
    LIU Yan, MA Yu, WANG Xiao
    Forensic Science And Technology. 2021, 46(1): 40-45. https://doi.org/10.16467/j.1008-3650.2021.0007
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    Objective To prepare the ZnS and ZnS:Cu inorganic ultraviolet (UV) fluorescent materials for developing sweat latent fingermarks based on their putative high fluorescence intensity, wide-object applicability, excellent handprint visualization and simple fabrication. Methods Through one step liquid-phase coprecipitation reaction, ZnS was prepared via the reaction of zinc acetate with sodium sulfide, so was ZnS:Cu from addition of sodium sulfide into the mixture of zinc acetate plus copper chloride (Cu2+ is to improve the fluorescent property of the fabricated ZnS material), therewith resulting in having the two inorganic UV fluorescent materials produced. With such two above-prepared materials, latent sweat fingerprints were developed on various common substrates (white stamping paper, glass slide, iron-rack plane, white-tile lined surface, matte countertop, stainless steel surface) and the complex ones (color-mixed patterned tile, beverage bottle’s label plastic sheet and magazine’s copper-coated cover). The fingerprint visualization was also compared against the conventional phosphor-powder method. Results ZnS is an inorganic UV fluorescent material, and its modified version of ZnS:Cu demonstrated the prominence of enhanced fluorescence intensity, stronger stability, and wider scope of emission wavelength spectrum so that it is able to develop sweat latent fingerprints on more various substrates, exhibiting different effects along with the adjustment of wavelength of the excitation light. Conclusions The inorganic fluorescent material ZnS and its modified version ZnS:Cu can develop sweat latent fingermark on different objects, with the latter owning better developability.
  • Algorithm on Trajectory of Spherical Projectile with Known Impacting Angle and Velocity
    DONG Biqiang, HE Weiyu, LIU Guangzhou, FANG Cheng, ZHANG Jinzhong
    Forensic Science And Technology. 2021, 46(1): 46-51. https://doi.org/10.16467/j.1008-3650.2021.0008
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    From time to time, such cases occur of building (usually window) glass having been broken with projectiles (bullet/pill/slug/pellet), leaving some difficult for investigators to solve. For these cases, the projectiles and their trajectories are the key clue and evidence. Therefore, this paper tries to design an algorithm to compute the ballistic trajectory of the projectile hitting towards the glass. This exploration takes the projectile’s impacting angle and velocity as basic parameters. The targeting windowpane is set under two conditions: vertical and/or tilting to the ground. Trigonometric function numeration and parameter substitution are used into calculation. Through the presetting or reverse extrapolation of several jointing parameters/factors (i.e., the ballistic parameters just at the impacting moment, the two-dimensional image parameter of bullet hole on the glass surface, the relevant angles, the parabolic track, the direction of ballistic trajectory), the ballistic trajectories are finally established about the projectile hitting glass under the two conditions. With simulation, such an algorithm of ballistic trajectory can reappear the parabolic trajectories of small spherical objects. This computation algorithm could play its role into investigating the cases with the pertinent trajectory to simulate the projectile hitting building glass.
  • Surface Enhanced Raman Spectroscopy Applied in Rapid Detection of Food Poisoning
    BU Quanmin, YU Shuang, ZHANG Miaomiao
    Forensic Science And Technology. 2021, 46(1): 52-57. https://doi.org/10.16467/j.1008-3650.2021.0009
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    Objective To establish a method of Raman spectroscopic analysis about five poisons likely envenomed into common foods. Methods Five toxicants/poisons of cyanide, paraquat, chlorpyrifos, thimet and diphacinone were respectively spiked into three common food materials (drinking water, smashed apple and roast duck flesh), having them extracted with the relative water, acetonitrile and ethyl acetate. Surface enhanced Raman spectroscopy was adopted to detect the extracted toxicants. Results Each toxicant has shown its own unique Raman signals that are capable of being used as the basis for qualitative discrimination. The detection limits were no more than 1μg/g for cyanide in drinking water, fruit and roast duck flesh, demonstrating the individual 0.05~0.1μg/mL(g), 0.05~1μg/mL(g) and 0.1~1μg/mL(g) for paraquat, chlorpyrifos/thimet and diphacinone, respectively. The results proved that the adopted method is eligible for rapid detection on scene. Conclusion The method established here is of simple operation, fast analysis speed, having provided a correct solution for rapid detection/screening of poisons/toxicants.
  • Characteristics of Marks Imprinted from Inked Silicone Biomimetic Fingerprint Film
    JIANG Huan, HOU Shuo, GAO Shengji
    Forensic Science And Technology. 2021, 46(1): 58-61. https://doi.org/10.16467/j.1008-3650.2021.0010
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    Objective To discern the difference of characteristics between the imprinted marks from silicone bionic fingerprint film and real finger so as to provide a basis for identification of silicone bionic fingerprint impresses. Methods The bionic fingerprint film was made with liquid silicone, having it pressed onto inkpad along with human real finger so that such two kinds of fingerprints were made onto A4 paper where both the silicone fingerprint film and human finger were vertically impressed under three forces of small, moderate and intensive strength. The so-obtained two kinds of fingerprints were photographed and extracted, having their features and differences compared. Results The imprints from the bionic fingerprint films were mostly seen of “blank” and “broken” signs, revealing irregular and uneven edges, having various breadths of small furrows with the pressing force strength changing yet no presence of distinct nuance. Real fingerprints showed natural and coherent lines. Conclusion There are differences between the characteristics of silicone bionic fingerprint film impresses and real fingerprints, therewith capable of being used for identification of silicone bionic fingerprint impresses.
  • Rapid Detection of Modafinil Tablet with Laser Confocal Micro-Raman Spectroscopy
    WANG Wen, KONG Weigang, CHEN Yufen, TAO Ke
    Forensic Science And Technology. 2021, 46(1): 62-65. https://doi.org/10.16467/j.1008-3650.2021.0011
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    Objective To establish a rapid method for qualitative analysis and determination of modafinil tablet with Raman spectroscopy. Methods Sampling Modafinil tablet and its standard specimen (for controlling) were subjected to Raman spectroscopic testing into their respective ground powder. Results The Raman spectra of the two kinds of Modafinil material were shown as identical from comparison, demonstrating the test is reliable and the result acceptable. Conclusions The controlling Modafinil is of better response, better peak shape, accurate peak position, capable of providing credible reference with suppressing the minor interference from starch and other substances added into the tablet. The established method is simple, efficient and accurate, therefore eligible for the grass-root law-enforcing/detecting departments to conduct rapid qualitative analysis for the seized Modafinil tablets.
  • Identification of Forged Signature from Writing Robot
    ZHU Mingxin, LI Mengjie, XU Runjie
    Forensic Science And Technology. 2021, 46(1): 66-69. https://doi.org/10.16467/j.1008-3650.2021.0012
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    Objective With advent of the writing robot that is able to imitate human handwriting and personal signature, the writing-robot-forged signature is sometimes encountered for forensic identification. The characteristics of signature forged from writing robot are different from those of the real man-made, thus capable of building up a creditable foundation for the involving identification. Here, the experimental research was to conduct on the characteristics of writing-robot-forged signature so as to help reduce the misjudgment in the relevant document examination and identification. Methods Taken of the real man-made handwriting as template, one mainstream market-sold writing robot was selected to imitate the template to produce its writing with different pens that were also used by people to write the same words as those made with the writing robot. The comparison was carried out between the two kinds of written words through direct naked-eye and microscopic observation plus the reflection transformation imaging (RTI) scrutiny. From the main differences summarized between the two kinds of handwriting, an effective examination and identification into document was to sum up. Results The characteristics of writing-robot-forged handwriting were mainly shown as: 1. The combinatorial characteristics of single words are highly consistent. 2. The stroke order of a single word is exactly same. 3. The signature is almost reproduced with high fidelity. 4. The starting and ending strokes keep a constant pressure. 5. Some strokes will appear distorted and shaken. 6. The overall strokes are even. 7. The movement of the used pen is rigid and less of gesture. Conclusions There is a significant difference between the writing-robot-forged handwriting and the real man-made. Reflection transformation imaging (RTI) should be used for observation to achieve a better identification effect.
  • Tenax GR Adsorption and Desorption for Extraction of Residual Gasoline at Fire Site
    MEN Tengteng, LIU Haixu
    Forensic Science And Technology. 2021, 46(1): 70-72. https://doi.org/10.16467/j.1008-3650.2021.0013
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    Objective Against the problem that effective constituents likely dismiss from the evidential gasoline residue due to the complexity of ordinary extraction and handling at the fire scene, a rapid innovation was to try with Tenax GR adsorption and desorption to make the gasoline residue picked up conveniently and efficiently. Methods Tenax GR absorption tube was placed into a container inside which the object or material holding gasoline residue had been already put. The container was afterwards sealed to heat within an oven at 60℃ for one hour to make the effective constituents from gasoline residue absorbed into the tube. The Tenax GR absorption tube was undergone through thermal desorption to release its holding substances that were successively analyzed with GC/MS. Results Tenax GR adsorption and desorption was revealed able to detect the gasoline residue of its characteristic components: toluene, dimethylbenzene, trimethylbenzene, tetramethylbenzene, naphthalene, methylnaphthalene and indan compounds, showing the detection limit being 0.25pL/mL. Six Tenax GR adsorption tubes gave the average RSD of 2.43% for stability test. The preservation sustainability manifested the relative deviation was respective of 6.3%, 14.4%, 8.7%, 18.3% and 11.6% from the corresponding deposition of well-absorbed Tenax GR tubes for 7, 15, 30, 60 and 90 days. Conclusion The innovation is easy to operate, high sensitive, relatively stable, suitable for the extraction and examination of gasoline residues at fire scene.
    • Reviews
  • Forensic Science Standardization Research: Sino-overseas Status Comparison and Development Trend
    ZHANG Ning, ZHAI Wanfeng, HUA Feng, XIE Qun, SUN Baoliang
    Forensic Science And Technology. 2021, 46(1): 73-80. https://doi.org/10.16467/j.1008-3650.2021.0014
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    Forensic science has been increasing to get wide concern and emphasis in China, even progressing into a rapider development. Thanks to years of research and promotion, forensic science standardization has also been gradually going deep into daily practice and incessant amelioration. Consequently, law enforcement and justice are essentially playing their more important and righteous roles with the assistance and regulation from the forensic standards and specifications to lead forensic science and technology into better application and assure the quality of forensic examination and identification. Therefore, forensic science standardization research is both fundamental and crucial, having home and abroad attached great importance to the standardization of forensic science, achieving many new ideas, thoughts and methods having emerged. This paper summarizes and compares the current situation of Sino-overseas forensic science standardization research from six aspects: standard orientation, standardization objects, standard granularity (participance and utilizability), standard architecture, quality control, and international standardization. Certainly, there exist similarities and differences in forensic science standardization research between China and foreign countries. The consensus lies on that standardization is the basis of quality, standards are adjustable with practice, and international standardization is of potential trend. Comparatively, foreign standard system tends to focus on “macro” perspective, paying attentions on quality management of standards, quality control of the whole process of forensic science implementation; whereas Chinese standard system places its concerns at “micro” horizon, having attentions paid to specific technical standards and laboratory test analyses. Likewise, more attentions are present with overseas standard operation at method validation and verification, quantitative evaluation of evidence strength and statistical researches. Finally, analysis has been also made about the future development trend of standardization research, e.g., strengthening researches on general standards, standards integration, method validation parameters, statistics and international standardization, with purpose to provide reference for promoting high-quality development of forensic science standardization in China.
  • Footstep Acoustic Recognition: Research and Progress
    FANG Yujie, ZHANG Song, LIU Jin, FENG Lei
    Forensic Science And Technology. 2021, 46(1): 81-86. https://doi.org/10.16467/j.1008-3650.2021.0015
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    Footstep acoustic recognition, one biometric distinguishing technology, is very promising with the continuous advancement of high-performance computer and deep-learning algorithm. Such a technology adopts the sound or vibration signals from walking people to recognize the relevant individual. It is specific of concealment, non-contact, difficulty to forge, and no requirement for cooperation of the recognized people. This article summarizes the footstep acoustic recognition system about its composition, basic concepts and performance evaluation indicators, with elucidation of the research development and progress. The focuses were paid onto the signal acquisition methods and eligible equipment, key technologies for noise reduction and endpoint detection signal preprocessing, temporal frequency domain and extraction of acoustic feature parameters, together with the applications of various pattern recognition approaches. Finally, the problems unknown of solution are systematically analyzed, with the discussions being made into both the hot issues necessary for further exploration and future trend.
    • Technical Notes
  • Laboratory of Modernizing Foot-trail Examination: Construction, Practice and Development
    JIN Yifeng, WEN Fuxing, DAN Qingsong, JIANG Xuemei, BAI Yanping, MA Yuanyuan, DAI Guoxin, XUE Zhiyuan, MO Xiaoting, LI Hongwei, LIU Guanhua
    Forensic Science And Technology. 2021, 46(1): 87-90. https://doi.org/10.16467/j.1008-3650.2021.0016
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    Foot-trail is among the physical evidence of highest occurrence at the case scene, frequently being the key “navigator” to search other evidential materials for scene investigation, therefore having it attached to importance. From time to time, foot-trail examination is cumbered with the insufficient talent training, deficient system construction and ineligible theoretical researches, thereby leaving it either unable to keep up with the pace of era or difficult to strongly support for case investigation and litigation. In 2018, a laboratory of modernizing foot-trail examination was collaboratively sponsored with Institute of Forensic Science of Ministry of Public Security and Criminal Investigation General Corps of Chongqing Public Security, focusing on playing its pivotal role to drive the whole forward, to realize the foot-trail examination technology into successive updating, innovation and leapfrog development. This paper introduces the laboratory of its planning, organizational structure, operational process and functional mechanism, as well as the prospect of promoting the foot-trail examination to develop with emerging technologies.
  • Testing of High-imitation Fingerprint from Silicone Gel
    LI Zhenzhen
    Forensic Science And Technology. 2021, 46(1): 91-95. https://doi.org/10.16467/j.1008-3650.2021.0017
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    A large number of high-imitation fingerprints increasingly emerged in the actual life, having brought great challenges to the fingerprint identification. In order to meet the need for identification of high-imitation fingerprints from cases, the high-imitation fingerprints were here made with both silicone gel and photosensitive resin plate to represent their copying versions of genuine and/or document-carrying fingerprints. Based on the high-imitation fingerprint involving to its production principle, formation mechanism, influential factors, regular patterns and various exhibits, both summarization and analysis were thereby carried out into the difference between the high-imitation and genuine fingerprints, with purpose to provide scientific basis for high-imitation fingerprint identification and examination.
    • Exchangeable Experience
  • Application of Sawn-apart Boles from Lumbered Trees into Their Special and Inherent Marking Features
    LI Dong, LI Tianbao, SUN Xiaodan, ZHANG Rui
    Forensic Science And Technology. 2021, 46(1): 96-99. https://doi.org/10.16467/j.1008-3650.2021.0018
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    Ordinarily, the integral marks occurred into the lumbered trees on their entire sawn-apart stubs/boles, having peculiar patterns. Therefore, evidence is able to provide with such marks when they are to test in the case of illegal logging. From the broken stubs/boles, there are usually special features found of, e.g., the wormholes, cracks and hollow cavities together with the inherent ones like the knots, annual growth rings, radial lines and bark texture. All the above-mentioned marks will definitely contribute evidential assemblage if they are totally and comprehensively examined into their harboring patterns/shapes on the severed boles, helping determine whether the involving marks can be regarded as the identification evidence and/or whether the separated stubs/boles are of same tree/provenance when the ligneous substance is devoid of the sawn-apart surfaces. Taken into a case investigation of woods pillage, the special and inherent marks were here introduced about their features from the cut stubbles, wormholes, hollow cavities, cracks, knots, annual growth rings, radial lines and bark texture, with the relevant testing methods and utilization being elucidated. The experience and knowledge described here would be valuable for the same or similar examinations and case investigation.
  • Analysis and Identification of Signature Produced from Low Capability of Handwriting: Case Report
    WANG Xiuhua
    Forensic Science And Technology. 2021, 46(1): 100-103. https://doi.org/10.16467/j.1008-3650.2021.0019
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    In document examination, the fewer signature scripts usually cause difficulty to judge their reality. When the samples were produced long time before (e.g., spanning several decades) and scarce of controlling specimen, more troubles will even bring into making an accurate judgment. This article was about an economic dispute case which involves with the document examination of signature scripts produced with low capability of handwriting more than 30 years before. Arduous and meticulous endeavors were consequently exerted into the tasks of examining the evidential materials, analyzing the samples, judging the characteristic values/features, investigating the background, conducting comprehensive evaluation and getting reference/insight from experience. The emphasis was put on full understanding of background materials about the parties and case. Deep inquiry was probed into the correlation between the case facts and identification requirements, along with the indispensable exploration through the exact reason of handwriting changing so as to avoid wrong appraisal of handwriting characteristics that would result from changing of writing habits. Finally, a scientific, accurate expertise opinion was therewith brought forward.
  • Separation of Mixed STR Profiles through Next Generation Sequencing: Case Report
    WU Yujian, FANG Hui, LIU Cuilan, WEI Tian
    Forensic Science And Technology. 2021, 46(1): 104-107. https://doi.org/10.16467/j.1008-3650.2021.0020
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    Objective To explore the applicability of next generation sequencing (NGS) into STR (short tandem repeats) genotyping of mixed DNA. Methods DNA was extracted from one sex-harassed woman with both the swab of wiping the woman´s neck and blood samples that were collected through the case. The Precision ID GlobalFilerTM NGS STR Panel V2 was used to prepare the library that was subsequently sequenced by the Ion S5 sequencer. The data were analyzed by Torrent_Suite_v5.2.1 software, with the relevant STR profiles being compared between the sequence- and length-based STR ones. Results Sequence-specific allelic subtypes were found in five loci: D8S1179, D21S11, D2S441, D2S1338 and D10S1248, thereby having made the relevant mixed STR profiles successfully separated. Conclusion The allelic sequence information parsed through NGS can assist in separating mixed STR profiles.
  • A Case of Homicidal Death from Poisoning with Pure Carbon Monoxide Gas
    DONG Chaoxiu, JIAN Xintian, LAN Shuangling, WU Kaixuan, GUO Hongmin, SUN Junhong
    Forensic Science And Technology. 2021, 46(1): 108-110. https://doi.org/10.16467/j.1008-3650.2021.0021
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    Death from poisoning of carbon monoxide (CO) gas is common in cases of suicide and/or accident. It is rare to be reported of a murder using pure CO gas in China or abroad. This paper narrates a homicidal case where a bottle of pure CO gas was adopted to bring the victim into death, such a covert and seldom-seen homicide. In order to avoid legal punishment, the suspect even falsified the crime scene, resulting in difficulties for the investigators. Through careful investigation into the crime scene plus autopsy, evidential material extraction and examination, together with scrutinous survey and interview, the death cause was finally clarified and the suspect was identified, eventually having the crime process fully reconstructed. Summarization and analysis were here made on the key points and difficulties in solving the case, with purpose to provide assistance and reference to the peers.

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