25 August 2015, Volume 40 Issue 4
    

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  • The Uniqueness of Toolmarks Based on Theoretical Characteristics Model
    YANG Min, MOU Li
    Forensic Science And Technology. 2015, 40(4): 259-262. https://doi.org/10.16467/j.1008-3650.2015.04.001
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    Tool marks are of the most often present on crime scene. The examination of toolmarks including impression evidence and the striation one has long been based upon the assumptions that a particular tool-mark may show uniqueness due to its physical characteristics and position relative to other marks. Obviously, the uniqueness of a toolmark is the premise of its identification. The theoretical issue of the uniqueness for toolmarks, however, has rarely been involved in the previous literatures. In this study, the theoretical models of individual characteristics for impressed and striated tool-marks were studied with the practice of toolmarks examination. The uniqueness of toolmarks was also studied by mathematical probability to identify the likelihood of occurrence. The Results have proven the validity of the uniqueness for toolmarks, and in theory, provide supportive explanation for identification of toolmarks as admissible evidence in the court.
  • Discrimination of Straight Handle Bolt Cutter from Hydraulic Bolt Cutter Using the Angle Between Burglarproof Grid and Top Plane on the Cutting Surface
    ZHU Zhongbo, XIANG Jin, LIU Sihai, LI Feng
    Forensic Science And Technology. 2015, 40(4): 263-265. https://doi.org/10.16467/j.1008-3650.2015.04.002
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    Objective To establish a rapid method of distinguishing straight handle bolt cutter from hydraulic bolt cutter by the cut burglarproof grid at crime scenes. Methods One type of hydraulic bolt cutter and three different types of straight handle bolt cutter with respective length of 450, 600, 1050 mm were employed as experimental tools. Eight various types of burglarproof grids were simulated using steel bars on the ground. The distances between bars were 110, 100, 90, 80, 70, 60, 50 and 40mm, respectively. The tools were used to cut burglarproof grids under some limited conditions, and the cut created a plane on the top of the cutting surface of the steel bar. The angle between the top plane on the cutting surface and burglar-proof grid was measured and analyzed. Results On the burglarproof grids with eight different spacing distance, the angles created by straight handle bolt cutter were measured in a range of 30°~150°, meanwhile, the angles created by hydraulic bolt cutter ranged from 0° to 75° or 105° to 180°. Conclusions Except for the overlapped range of angle created, the rest has distinguishing characteristics which can be utilized to differentiate the two types of bolt cutters. According to the angle between the top plane on the cutting surface and burglarproof grid found at the crime scene, 75°~105° indicates the related tool as a straight handle bolt cutter, while 0°~30°or 150°~180° indicates a hydraulic one. Hence, the angle between the top plane on cutting surface and burglarproof grid can be an effective index to differentiate straight handle bolt cutter from the hydraulic one.
  • A Casting Method for Physical Match of Objects with Curved Surface
    YUAN Guoping, WANG Ping, JIANG Tieqi, LIU Jin
    Forensic Science And Technology. 2015, 40(4): 266-268. https://doi.org/10.16467/j.1008-3650.2015.04.003
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    Evidential fragments are often encountered at crime scenes, particularly those involving in motor-vehicle accidents and crime. The objects are often broken from external force, leading to fragmentation. However, due to the complex structure of the object’s surface and the large number of fragments, fitting all the fragments together becomes extremely difficult. Here the fitting Methods , implementation steps and operation specifications for reassembly under different circumstances were tested and optimized. Overall separation tests of 30 surface-different objects under 50 various conditions were implemented to identify the fragments and the amount of the original objects. The high-strength materials and their auxiliary for three-dimensional footprint lining extraction were utilized to cast corresponding object’s liner (lining) models by perfusion or adhesion Methods. The model, as a framework, was compared with the relevant debris to put them together. The reconstruction of a glass bottle was taken as a specific example to illustrate the test procedure. The new method has proven its practical value for the examination and identification of similar broken trace evidence. The standardized examining steps and related precautions were also proposed.
  • A New Pretreatment Method for Toolmarks on Bone
    WANG Zhen, LIU Jin, YAN Yu, HE Chenjiao
    Forensic Science And Technology. 2015, 40(4): 269-271. https://doi.org/10.16467/j.1008-3650.2015.04.004
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    Toolmark on bone was selected as research object and a new pretreatment method on defatting bone was developed in this paper. The study aims to enhance the characteristics of toolmarks on bone and extend the storage time of similar evidence. The pig claviform bone was selected as the experimental material to generate the tested tool marks. A total of 30 samples were made by the pig bones being sawn with a steel saw and real conditions simulated for toolmarks in crime scene. The influences of different types of organic solvent, steps of defatting and time of treatment on features of toolmarks on bone and defatting ratio were analyzed with simulating experiments in laboratory. The organic solvent, steps of defatting and treatment time were optimized, and a new and effective pretreatment method for defatting bone by absolute alcohol, petroleum benzin and infrared drying was developed. Instead of destroying the features of toolmarks, the method could enhance the contrast of striation present on fracture surface of bone, convenient for further recovering and examining toolmarks on bone by photography. Meanwhile, no pungent smell was produced from a defatted bone after long storage in glassware. This paper presents a new pretreatment technique of defatting bone to safeguard further toolmark determination and storage of evidence.
  • Determination of the Suspect Tool by Comparing the Impressed and Striated Marks Left on the Cutting Surface
    CUI Jun, YANG Yubo, WANG Yonghui, SUN Jianjun
    Forensic Science And Technology. 2015, 40(4): 272-274. https://doi.org/10.16467/j.1008-3650.2015.04.005
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    Determination of the Suspect Tool by Comparing the Impressed and Striated Marks Left on the Cutting Surface
    • Research Articles
  • Research on Mechanism of Paper Burningby Thermogravimetric Analysis
    QIN Da, HAN Xingzhou, WANG Xiaoguang, QI Fengliang, WANG Zijie, GUO Zihan, HAO Hongguang
    Forensic Science And Technology. 2015, 40(4): 275-279. https://doi.org/10.16467/j.1008-3650.2015.04.006
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    The examination of charred document is a challenge and usually requires a careful application of certain scientific techniques due to its unstable property. To address this issue, the mechanism of paper burning was studied in this paper. Here thermal-gravimetry (TG) was applied to investigate five kinds of paper, along with their TG and derivative thermogravimetric curve (DTG) observed at different atmospheric conditions. The results showed that the shape of curves,albeit similar, varied with the physical and chemical composition of paper. In the burning process, dehydration and depolymerization are the two main pathways for cellulose, the major ingredient of paper. The heating rate indicated little influence on the curves while the sort of atmosphere worked strongly. The reason is due to the lack of tar oxidation when nitrogen used as the atmospheric environment. At moderate temperature, de-polymerization prevails and the tar can be observed. With temperature increasing, the tar and cellulose are further decomposed, leading to products of high boiling-point. According to the results, the charred document can be classified as one of the dehydrated, tarred,charred and ashed. Except the ashed stage, the other three can be handled and the writing whereon can be deciphered. The results exposed hereof may provide a fundamental for examining and deciphering charred document.
  • Victimology in Homicide Crime Scene Analysis (Part Ⅲ )
    MIN Jianxiong
    Forensic Science And Technology. 2015, 40(4): 280-282. https://doi.org/10.16467/j.1008-3650.2015.04.007
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    Victimology in homicide crime scene analysis, the serial treatise published along with every issuance of the journal recently, has already been read twice by the public. In the first two pieces of the serial, an introduction to the discipline and the relationship between victims’ identity and crime scenes were illustrated and discussed. This paper, the third one of the serial treatise, places its emphasis on the life background of victims, aiming at calling forensic investigators’ attention to this aspect that sometimes is neglected in practice but can play key effects in solving relevant crimes. To address the matter, four portions are expounded here by the victims’ inclination of emotion to begin with, which takes as examples of two cases where all the victims died from thuggee with the decedent in one case through his willingness to conduct homosexuality and two men in the other one involved in the murderer’s pretence to answer their marriage-seeking. For the role of relationship between family members in homicidal crime, the explanation is assisted with a case where a wife killed her husband because of the final inability to endure the chronic maltreatment of the dead. Certain interpersonal relationships are at times implicated in murder case, and an auxiliary instance was shown with five people dead as a result of the killer’s hatred against his five work-mates’ repetitious mocking and bullying. Occasionally the culprits take advantage of victims’ religious belief and superstition to commit crime. The fourth portion is concerned with this point, highlighting it in a case that three female pilgrims were lured to the remote places to be slain when the murderers, conjecturing to achieve or consolidate their illusional noblest status of “emperor” or “empress” by way of killing people, found the dead bringing incense to get benediction from praying to some supernatural existence. Besides, many other general essentials linking to peruse the crime scenes are mentioned as well in this paper.
  • Evaluation of Fingerprints Developed by Physical Developer and Oil Red O on Paper Surface
    WANG Mingchao, WANG Danhua
    Forensic Science And Technology. 2015, 40(4): 283-287. https://doi.org/10.16467/j.1008-3650.2015.04.008
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    Objective Paper is frequently encountered in crime scene, with deposited fingerprints containing grease or oil on its surface. Physical developer and Oil Red O, as two effective ways to develop these fingerprints, have been used in case work abroad, both of which can color the friction ridge by combining with substance in fingerprint residues especially the oil or grease, consequently making the latent fingerprint visible. However, the two Methods have not drawn enough attention in domestic forensic practice. This paper explores the potential advantage of physical developer and Oil Red O respectively in order to provide a reference for the forensic scientific research and crime investigation. Methods Natural fingerprints ranging from strong to weak (‘depletion’ prints) selected from eight donors randomly were sequentially deposited on strips of common copy paper, pink copy paper, thick white copy paper, thick kraft paper, thin kraft paper, fax paper, thermal paper, offset paper, pressure-sensitive paper, newspaper and scratch paper. In order to observe the obvious contrast, the ‘split print’ approach was used by cutting the strips from the middle of the developed prints into two parts for physical developer and Oil Red O. Samples treated with physical developer were immersed into the maleic acid, distilled water, the working solution and distilled water sequentially. Those treated with Oil Red O were immersed into the dyeing solution and pH 7 buffer. The developed fingerprints were divided into four grades according to the quality of the developed friction ridges, and the comparison was also based on this scale of score standard. Results The principles of coler reaction by the two solutions differed in the color combination between the particles and fingerprint’s residues left on paper surface. The quantity and quality of fingerprints developed by both Oil Red O and physical developer were affected with sample exposure, the solution processing environment, the operating conditions and other factors. Ten different papers showed different development Results . Oil Red O displayed some advantages over physical developer according to the comparison of the solution preparation, operational aspects as well as the final Results .Conclusions Oil Red O method is superior to physical developer and has good application prospects in fingerprint development.
  • Detection of Inherent Fingerprint Fluorescence by 445 nm Laser
    YANG Feihuang, GAO Shuhui, HOU Yushi
    Forensic Science And Technology. 2015, 40(4): 288-290. https://doi.org/10.16467/j.1008-3650.2015.04.009
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    Objective In crime scene investigation, it is difficult for investigators to quickly detect and collect some long-deposited and complicated fingerprints. This paper aims to explore the inherent fluorescence imaging quality of fingerprints left on different surfaces for various time, by a Portable Laser Biological Specimen Detector setting at wavelength of 445 nm. Methods Fingerprints, left on 5 different objects,were regularly extracted and visualized by 445 nm laser and an ultraviolet CCD. By compared the different visualization effects between the above handling, the impact factors on extracting potential fingerprints by 445 nm laser were analyzed along with the best time to take photos. Results Better images had been obtained from fingerprints of oil-sweat mixture by 445 nm laser. The visualization effect varied from different length of time. The fingerprints on pervious objects were displayed better with the increase of time, and kept stable after 2~4 weeks. As for impervious objects, the fingerprints were at first developed better with the increase of time. However, the visualization was getting worse past a month. Conclusions The fingerprint inherent fluorescence detected by 445 nm laser is influenced by such factors as smooth degree, object permeability and types of fingerprint, and hence the best visualizing time should be determined from different surfaces. Meanwhile, ultraviolet reflex photography is complementary to 445 nm laser photography in the process of fingerprint visualization since it is more suitable for the fresh greasy fingerprint on impermeable objects, while the 445 nm laser photography is better for the aged sweat or oil-sweat fingerprint on pervious objects. This research produces a potentially more accurate and reliable methodology for fingerprint identification.
  • Determination of Crossing Sequences Between Laser Printed Text and Seal Impression by Ultraviolet Fluorescence
    WANG Shaofang
    Forensic Science And Technology. 2015, 40(4): 291-295. https://doi.org/10.16467/j.1008-3650.2015.04.010
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    Objective This paper aims to demonstrate a new, non-destructive, quick and reliable way for determining crossing sequence of laser printed text and stamped seal impression using ultraviolet fluorescence. Methods A Video Spectral Comparator (VSC5000) was applied. 72 document samples, prepared with 6 brands of laser printer and 3 types of inkpad, were examined under ultraviolet light with adjustment of parameters including color filter, contrast, brightness and others. Then fluorescence reflection on overlapping region of seal impression and printed text was observed. Results There was great difference at two crossing sequences, that is, printed text over seal impression and seal impression over printed text. In the crossing region of seal impression over printed text, the text was darker and wider, but the strokes maintained continuous and complete. In the crossing region of printed text over seal impression, the text kept the same color and width with those separated from the stamp impression, but some of them were interrupted or incomplete. Conclusions The ultraviolet fluorescence method is a very effective and attractive technique for determining the sequence of laser printed text and stamped seal impression. Some challenging samples such as year-long documents, unclear stamps, and those not covered yet here, can be detected in further study.
  • Preliminary Research on Distinction of Common Counterfeit Currency
    ZOU Jixin, YU Jian, QI Fengliang, QIN Da, SUN Lin
    Forensic Science And Technology. 2015, 40(4): 296-299. https://doi.org/10.16467/j.1008-3650.2015.04.011
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    Crimes of counterfeiting currency have been getting more complicated in recent years as there are more and more phony money printed by printing presses, laser printers, inkjet printer and the offset. The criminals have been improving the forging techniques by modifying their printing machines, printing ink, and paper in order to replicate the security features of RMB in great detail. Identification of the counterfeiting Methods plays a significant role in providing clues for counterfeit crime investigation. In this paper, the counterfeit currency seized from the crime scene was studied together with samples printed by printing press, color printer and color copier. The research was also conducted to detect whether the counterfeits were printed by laser printer or inkjet printer and what brand of printer was used. A VSC6000 document examination workstation and stereo microscope were applied to observe the image-text characteristics, minor details of the counterfeits and to find how the ink dots were formed. With the differences detected, monochrome printing could be distinguished from four color printing in the aspects of the ordination of image-text, color matching, and the like. The major brands of color inkjet printer such as Canon, HP and Epson were identified by the size of dots, pattern of ink piled up, space between dots, and the others. By the shape and the tracking code of the color laser printers, the brand of the printer could be distinguished. Through a large amount of counterfeit currency, the characteristics of monochrome printing and four color printing were found, and therefore counterfeit currencies by printing presses, color printers and color copiers can be distinguished. The method has been applied in cases, where one counterfeit currency was identified to be printed by an Epson color inkjet printer and another counterfeit currency printed by a Fuji Xerox laser jet printer. There were other factors that might influence the analysis Results , such as printer modification, the plug-in ink box used to improve the quality of the inkjet printing. The research needs to be further carried out to identify the brands of laser printer as its image-text is more complicated and the printer tracking code of laser printer is waiting to be understood clear on the counterfeited currency. The Methods provided in this paper will be beneficial to people working on identification of counterfeit currency.
    • Reviews
  • Forensic Identification of Thoracolumbar Compressed Fracture
    ZHANG Xin, LIU Ying
    Forensic Science And Technology. 2015, 40(4): 300-304. https://doi.org/10.16467/j.1008-3650.2015.04.012
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    Vertebral compressed fracture, possibly caused by osteoporosis or a trauma, is one of the most encountered cases in forensic clinical settings. Determining the time of vertebra crush and identifying the cause-effect relationship of vertebral compressed fracture with osteoporosis have always been a challenge for forensic medical examiners. However, there has not yet been better approaches brought up by either domestic or international clinical including forensic communities till present. This article reviews current researches on the mechanism of collapse of vertebra, classification and characteristics of thoracic and lumbar compressed fractures, and the diagnostic criteria of osteoporosis as well. An introduction to the concept of risk factors associated with fractures is also presented. Three most common techniques in clinical settings, quantitative ultrasound (QUS), dual-energy X-ray absorptiometry (DXA) and quantitative CT (QCT), are compared comprehensively for the measure of bone density. Their pros and cons are outlined respectively. In addition, magnetic resonance imaging (MRI) is specifically introduced of its most current progresses, its applications in diagnosis of vertebral compresses fractures, as well as its implementation to predict acute versus chronic vertebral compressed fracture. Finally, based on the characteristics of forensic clinical work, we propose an initiative of implementing magnetic resonance diffusion weighted imaging (MR-DWI) and magnetic resonance chemical shift imaging (MR-CSI) technology in the examination of vertebral compressed fractures with purpose to play their potential to determine the timing and acuity of fractures. Moreover, we also put forward the application of the bone density and its fracture threshold in recognition and interpretation of the cause-effect relationship between osteoporosis and vertebral compressed fracture.
  • Psychoactive Substances Analysis: A Literature Review
    LI Peng, HE Jianfeng, LIU Kelin, ZHANG Chunshui, GAO Lisheng, ZHENG Hui
    Forensic Science And Technology. 2015, 40(4): 305-311. https://doi.org/10.16467/j.1008-3650.2015.04.013
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    In the past decades, an ever-increasing number of new psychoactive substances (NPSs) have appeared in the recreational drug market, and analytical toxicologists have to continuously adapt new screening Methods to identify the latest NPSs. The daunting challenges are how to accurately monitor the state of NPSs and how to determine an enormous range of trace and ultra-trace analytes present in sample matrixes with complex or variable compositions. Here we present a critical overview of the analysis of some of the most commonly encountered and most dangerous substances. The rational method development, validation and transfer of robust gas chromatography-mass spectrometry (GC-MS), and important factors impacting the incurred sample analysis are discussed. The mature technologies coupled with GC-MS used in most quantitative bioanalytical laboratories, such as hollow fiber-based liquid phase microextraction (HF-LPME), electrosorption-enhanced solid-phase microextraction (EE-SPME), are also covered. Liquid phase separation techniques coupled with mass spectrometry (LC-MS), is also expounded in this paper. Due to its high specificity, speed and selectivity, LC-MS has long been deployed in NPSs detection to assess not only these continuously changing molecules but also their metabolites, and will probably surpass GC-MS as the leader of the so-called hyphenated techniques in the near future. Further challenges presented are to make sure that new methodologies and equipment comply with the principles of sustainable development, so in the third part, some new techniques, triple quadrupole time-of-flight mass spectrometer (QQQ-TOF-MS), graphite screen-printed electrode (GSPE) and among others, are discussed as well. Finally, one of the key issues, highlighted from future perspective, is to narrow the time gap between the first appearance of an NPS and the availability of reference standards of parent drugs and metabolites. Otherwise, the identification of NPSs and/or their metabolites will remain preliminary.
  • Latent Fingermark Development: Literature Review and Prospect
    ZHAO Yabin, LUO Yaping
    Forensic Science And Technology. 2015, 40(4): 312-317. https://doi.org/10.16467/j.1008-3650.2015.04.014
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    Fingermark is one of the most valuable physical evidence and generalized proof of identity for its characteristics of specialty and stability. Latent fingermark, the most common evidence, poses the most challenges when being examined to show contrast present yet non-sufficient between the mark and its support. Surface phenomena and environmental conditions play an important role in the choice of fingerprint detection techniques. In general, all surfaces bearing latent fingermarks can be divided into three types: porous, semi-porous and nonporous. Property of an unknown surface has to be considered before any attempt is made to develop latent fingermark. Preliminary test should be conducted on a similar surface before proceeding with any treatment of an evidential item. Along with the fingermark detection technology being improved, the process has been further optimized and its sensitivity and specificity being advanced. In this paper, the latest techniques and material used in different surfaces to enhance and record fingermarks are reviewed. A larger number of techniques are presented here and discussed according to surface properties from practical perspective. For example, optical detection, fingerprint powder, small-particle reagent (SPR), cyanoacrylate fuming and vacuum metal deposition (VMD) can be used to nonporous surface. Ninhydrin, physical developer (PD) can be used to porous surface, some miscellaneous techniques can be applied to a wide range of porous and nonporous surfaces, even for some challenging surfaces. Furthermore, some modern instrument analysis techniques can be used to enhance the visualization of latent fingermarks. Finally, we summarize the advance of research on the development of latent fingermarks, discuss the challenges facing the fingermarks examiners, and predict the future and perspective research of latent fingermarks development.
    • Forum
  • Several Key Issues for China National DNA Database Development
    LIU Bing
    Forensic Science And Technology. 2015, 40(4): 318-323. https://doi.org/10.16467/j.1008-3650.2015.04.015
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    China national DNA database has a history of 15 years and has kept more than 30 million short tandem repeat (STR) profiles, generating over 1.5 million matches assisting in more than 1 million investigations. In recent years, Y chromosome STR (Y-STR), single nucleotide polymorphism (SNP), single cell testing, and high throughput DNA sequencing technology have been continuously introduced in forensic science. Currently, the DNA database could only allow the traditional direct match and simple mode of familial searching for personal identification, far behind the high-tech assays which is expected. How to utilize these new technologies to develop new stratedgies for China national DNA database? How to further develop China DNA database and maximize its efficiency? This paper discusses the development in the light of 4 issues. First of all, the core loci of database need to be set prior to increasing the number of autosomal STR loci, even though there is a consensus on the quantity change. As for the new genetic markers, such as SNP, the attitude of “good will of expectation” should be in line with “prudent wait-and-see”, since there is few possibility to use SNP commonly in a database with ten-million profiles. It is more likely that the genome-wide analysis will bring the great change to the DNA database in the future. Still, the special familial searching is a supplementation and inevitable choice for DNA database in case of a low coverage of the population. But this searching has to follow strict rule. Finally, Y-STR database development is Objective and urgent, but it must be cautious as personnel sample collection might be involving legal, social and other problems; the pedigree in sociological term may not equal to genetic one; positive evaluations of Y-STR database should be also built on deductive method; a balanced development of database should be considered of both costs and benefits. Therefore, without a theoretical framework constructed with rigorous deduction, especially prior to the mathematical model of evaluation, Y-STR database is only a matter of empirical, rather than scientific, letting alone the difficulty to assess the value of such experience for others. In conclusion, as a DNA database with ten-millions profiles, any change related to fundamental issues concerned with development, security or stability must be dealt with comprehensively and scientifically.
    • Technical Notes
  • Analysis of the Death Caused by Multifactorial Factors Following Traffic Injury
    HUANG Jiacai, HUANG Sixing, ZHANG Xianguo, KONG Bin, WU Yong, ZHENG Tao, LI Maoyang, ZE Na
    Forensic Science And Technology. 2015, 40(4): 324-326. https://doi.org/10.16467/j.1008-3650.2015.04.016
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    A methodological quest is conducted on forensic identification about multiple factors resulting in death following traffic injuries. Three relevant cases were collected, and the victims involved in traffic accidents died within one or several days after suffering from traffic injuries and receiving medical care and/or treatments. The systematic autopsy of the deceased had been taken so as to identify which factors to cause death and their contributions to the outcome. There were one and more other negative factors exerting their effects to lead the victim’s death besides the traffic injuries. In order to find out the exact reason of death following traffic injuries, such actions should be executed as of obtaining all-around information about both the accidents and the victims, carrying out the systematic autopsy, logically analyzing the disease and complications (if any) the victim suffered when alive plus other physical and environmental negative factors, and finally defining the relationship among all the above factors and their participation rate to death.
  • Lockscreen Passcode Decryption on Android Smartphone Using a Custom Recovery
    SHI Suidong, LI Meng, LEI Ming
    Forensic Science And Technology. 2015, 40(4): 327-329. https://doi.org/10.16467/j.1008-3650.2015.04.017
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    The screening of crime-related smartphones can provide critical clues for case investigation. On examination of an Android smartphone with passcodes set up without turning on USB debugging, it’s hard to obtain evidence if the suspect doesn’t cooperate. A new method using a custom recovery is introduced. Since official recovery doesn’t have functions of backuping, restoring or flashing a custom ROM in light of the safety concern, a custom recovery was flashed on Android smartphone using the backup system function, and then decrypted the passcode file extracted from the backup file, or flashed a path to delete passcode files. Theoretically flashing a custom recovery is safe, as it only modifies the recovery partition without partition data changing. However, it is risky to some extent when flashing a smartphone. Some dos and don’ts are proposed in this paper.
  • Genetic Polymorphism of 19 STR Loci in Han Population in Jincheng
    LIU Yanjun, HE Xiaohua, GONG Zhigang, LI Lin, WANG Bing, ZHANG Tianlin
    Forensic Science And Technology. 2015, 40(4): 330-331. https://doi.org/10.16467/j.1008-3650.2015.04.018
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    The genetic polymorphism of 19 short tandem repeats (STR) loci in Han population in Jincheng Shanxi was studied using Goldeneye 20A STR Amplification Kit. 1233 unrelated individuals were investigated to obtain allele frequencies and forensic genetic data. No deviations of allelic frequency from Hardy-Weinberg equilibrium were observed (P>0.05). Heterozygosity (H) of 19 loci ranges from 0.639 to 0.919,matching probability (PM) 0.014 to 0.177; power of discrimination (DP) 0.806 to 0.987; polymorphism information content (PIC) 0.58~0.91; power exclusion (PE) 0.342~0.821.The cumulative discrimination power (CDP) and cumulative probability of exclusion (CPE) are 1-1.27×10-23 and 0.999999991, respectively. The result indicates that 19 STR loci are highly polymorphic and suitable for forensic personal identification and paternity testing in this area.
  • DNA Analysis of 1025 Touch Samples from Various Appliance Connectors
    DONG Yingchun, LI Shiliu, YAN Mengfei, LIU Zongwei, ZHU Yi
    Forensic Science And Technology. 2015, 40(4): 332-333. https://doi.org/10.16467/j.1008-3650.2015.04.019
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    Touch DNA is now often encountered in forensic investigation. Its successful acquisition is often crucial for solving the relevant cases. In this paper, 1025 pieces of touch DNA samples tested in our laboratory since 2012 are reviewed with the purpose to find some regularity. These samples were collected from various electric connectors consisting of mobile phones’ (156 pieces), net cables’ (416 pieces), power cables’ (155 pieces), displays’ (22 pieces), and USBs’ (276 pieces). The DNA was extracted with modified method of silica, amplified with AmpFLSTR® Identifiler® Plus PCR Kit, electrophoresed with ABI3500XL. Data were analyzed with GeneMapper ID-X. The Results showed that the detection rate was 93.6% for mobile phones’ connectors, 84.4% for net cables’, 82.0% for power cables’, 95.5% for displays’, and 89.5% for USBs’, with a total detection rate of 87.0% for all the 1,025 pieces of touch DNA samples. The method applied here is suitable to tackle the samples of touch DNA.
  • Examination of Plastic in Traffic Accidents
    LUO Yiwen, SUN Qiran, XU Che, BIAN Xinwei
    Forensic Science And Technology. 2015, 40(4): 334-337. https://doi.org/10.16467/j.1008-3650.2015.04.020
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    Plastic fragments are frequently present in traffic accident scene, especially the hit-and-run accidents. Samples collected from the scene are often very small, sometimes even smaller than one square millimeter in size. Forensic labs need to do comparison of the scene samples with the plastic of suspected car. In this paper, examinations of plastic in three traffic accidents were described and the characteristics of these plastic evidences summarized. The key points involved the collection and analysis of plastic samples were discussed along with the evaluation of the findings. Vehicles are usually fitted with the plastics, chemically different but visually similar, in positions close to each other for functional and aesthetic purposes. It should be careful for both accident investigators and laboratory analysts that some plastics might be altered in shape, color or other physical characteristics, after being affected by force or heat in the process of transfer. Micro-Fourier transform infrared spectroscopy (Micro-FTIR) is a quick, informative and non-destructive method for plastics analysis, therefore, both comparison and identification of plastics could be achieved by their FTIR spectrum.
  • Extracting the Deleted SMS Data from an Android Smart Phone
    LONG Yuan, XING Guidong, GUO Lili, CHU Chuanhong, ZHONG Lijing
    Forensic Science And Technology. 2015, 40(4): 338-339. https://doi.org/10.16467/j.1008-3650.2015.04.021
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    This paper introduces a digital forensic examination on storage dump from an Android smart phone to access the deleted SMS data. The SMS data had been deleted by the suspect from the Android smart phone. Part of the deleted SMS data could be recovered using DC-4500 mobile phone forensic system and Oxygen Forensic Suite 2014, but proved to be irrelevant to the case. Commonly, the above software can only analyze the SMS database file, thus the deleted data would no longer exist in the SMS database if the sqlite database had already recycled the storage space. Therefore, a new inspection method was deployed to access the deleted SMS data. At first, the Android phone was rooted and its hex-dump got with DC-4500 mobile phone forensic system, and then some keywords were selected and searched through the hex-dump by X-Way Forensics. Subjected to further analysis, the evidentially deleted SMS data fragment that the suspects tried to destroy after committing their crime, was finally found in the free space of hex-dump. Currently, Android smart-phones involved in cases are even more commonly emerging, resulting in the ever-increased necessity to get relevant hex-dumps from the phones and obtain data through keyword-searching into them. The method of this paper could be taken as a reference for future work.
  • Comprehensive Examination and Identification of Human Image in Poor-quality Video
    ZHANG Dazhi, XIANG Ning, ZHOU Peng
    Forensic Science And Technology. 2015, 40(4): 340-344. https://doi.org/10.16467/j.1008-3650.2015.04.022
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    Objective To explore a comprehensive method for examining and identifying human image in poor-quality videos based on a typical case. Methods In advance of the examination, a variety of available videos and related evidence were collected and submitted for assessment. The videos were organized and linked together as a single file to facilitate playback, visual inspections and analysis. According to the features depicted in videos, the head and facial morphology, clothing, somatotype and posture were determined as the examination contents and directions. Then the pictures reflecting multiclass human image features were extracted and cropped from the previously captured continuous video-images, and those used for comparison were chosen under similar pose, angle and orientation. Afterwards, a series of “side-by-side” comparisons and evaluations were conducted on the following aspects: the head and facial morphology, clothing features, body postures at key nodes in a gait cycle, foot landing direction, foot motion changes and habitual behavior. A photogrammetric analysis was also conducted to determine the height of the person depicted in the submitted videos. In the above-mentioned process, a slow motion and split screen video were made and used for presenting, comparing and recording the observed dynamic human image characteristics reflected with time lapsing. Finally, a comprehensive assessment was made according to the correspondence/discordance of the human image characteristics. Results All kinds of human image characteristics were consistent in their respective dimensions and thus they were mutually interrelated, complemented and supported. Their probative value and proving ability were optimized and improved, leading to certain identification. Conclusions It is a feasible and effective way for examination and identification of human image in poor-quality video by collecting sufficient image data and related evidence with comparability and conducting photographic comparisons from multiple dimensions with various Methods .

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