Objective To solve an unusual death case and develop a method for determining concentration of acetone in blood or urine samples from the dead body by headspace gas chromatography (HS-GC), which is quite helpful under certain circumstance when autopsy can’t be performed because of social customs, religious belief or other reasons. Methods A 67-year-old man, who had diabetes, was found dead in a hotel room and his family didn’t agree to perform an autopsy. In order to determine the cause of death, the blood and urine samples were sent to laboratory for poison and drugs analysis, but no common poison was found. Based on the excellent volatility, acetone in blood or urine samples was analyzed by a head-space gas chromatography system with hydrogen fire ionization detector (HS-GC/FID). Qualitative analysis result was obtained according to retention time, and quantitative analysis was performed by internal standard (tert-butyl alcohol) method. The average peak area derived from three replicate injections of each sample was used for the calculation of acetone concentration in blood or urine. Results Concentration of acetone in blood and urine was 6.89 mg/100mL and 57.1 mg/100mL respectively, both were much higher than the normal value. Conclusions Determination of acetone in blood or urine by HS-GC/FID provides a useful evidence for determining the manner of death, which is especially effective when short of pathology data. In such casework, thorough information about the dead should be taken into consideration to ensure the scientific deduction.

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.

： Objective To explore the technique and strategy about both investigation of the crime scene and DNA test for such biologically evidential materials as exfoliated cells adhered onto the glove imprints.. Methods DNA, individually extracted from four swabs of glove imprints collected in theft cases by an improved silica-bead method, was amplified by AmpFISTR Identifiler® Plus system, followed to conduct electrophoresis by 3500XL genetic analyzer, and finally undergone the genotyping by GeneMapper® ID-X software. Results DNA genotyping profile was successfully acquired from each of the four swabs. 17 cases were solved through the combination with the evidence of the DNA genotyping profile obtained above. Conclusions Glove imprints, in combination with the efficient DNA test strategy on the basis of their careful examination and extraction at crime scenes, can significantly improve DNA directivity, thereby making such biological trace-evidence exert its function effectively.

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.

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.

From DNA fingerprinting to multiplex STR amplification and detection, forensic DNA scientists witnessed the rapid advances in DNA technology and the substantial changes in ways of solving criminal cases during the past three decades. As a matter of fact, only incremental developments of forensic DNA technologies and the "passive comparison" mode of using DNA information could not meet current expectations for forensic genetics from crime investigators. It has been unprecedentedly emphasized that great efforts are needed for more powerful solutions that are automatic, high-throughput, precise, rapid and being support to the "active searching" mode of DNA information utilization. Under such circumstances, next generation sequencing (NGS) comes just in time. Chinese authorities and experts have already realized the great potential of NGS applications for forensic purposes, although the application of NGS in forensic science is still at initial stages, compared with its applications in fields of cancer diagnosis, genetic disease diagnosis, de novo sequencing, genome resequencing, transcriptome resequencing and drug discovery. More information can be obtained from a single experiment by analyzing the STR, SNP, Indel and RNA markers simultaneously, which could be impossible on routinely used PCR-CE platforms because of the limited amount of exhibits. In this article, the authors attempt to describe the basic concepts, developmental history and working principles of NGS to Chinese experts in the general field of forensic science and technologies, and share the updates of NGS-based STR typing, SNP typing and whole mtGenome sequencing during the past two years. Representative NGS platforms including the 454/Roche GS FLX system, the Solexa system, the SOLiDTM system, the Ion PGM^TM system and the MiSeq FGx^TM system were introduced. Annual statistics of research articles on NGS and forensic NGS were described and trends for related research were analyzed. Finally, perspectives of forensic NGS were presented and possible challenges including data analysis methods, openness of NGS systems and ethical issues were discussed in the hope of providing a reference for related research and applications.

Objective Biological evidential material, enclosed in forensic evidence package, may be transferred onto its package, making the DNA typing less detectable. Therefore, the lower transfer level is better, especially for the trace touch DNA samples. This study aimed to investigate whether the DNA is transferred onto forensic evidence package and the transfer rate between different types of evidential materials and packages. Methods With two kinds of forensic evidence package, the seal-lock plastic bag and yellow paper envelope, three kinds of trace touch DNA, four blood and saliva samples were prepared to simulate the packaging and transporting process. An individual, carrying a suitcase which contained all of the test samples, walked on a treadmill (running at 4 km/h) for 30 min, then went up- and down-stairs for five stories. DNA, extracted from the test samples and the evidence packages, was quantified, amplified and analyzed following the manufacturer’s standard procedures. The transfer rates were compared with two different packaging ways. Results The experiment showed that all of the test samples were transferred onto package at various levels and the average transfer rate was 22.06 %. The two types of packages were observed of significant difference (P=0.023) for their transfer rates, with those of the seal-lock plastic bag being estimated as 17.85 % and the yellow paper envelope as 26.27 %. The transfer rates of the trace touch samples were higher than those of the blood and saliva samples no matter whether they were kept in the yellow envelope or the seal-lock plastic bag. The loss of recoverable DNA from the samples to the evidence packages ranged from 1.84 % to 67.66 %. Conclusions DNA transfer occurs on the forensic evidence package to crop it, affecting DNA typing. Different types of samples have different transfer rates and so have the evidence packages.

Until present, China national DNA database has already gathered tens of millions of data, including not only the DNA profiles but also a large amount of information related to the time, space, means, type of the committed crime and the residence, nationality, individual behavior of the suspect. With the growing needs of public security, the data are still in rapid accumulation and growth. From 2011 to 2013, the database collected relevant data covering over 79.25% of murder and 40.53% of rape cases filed. Currently, the main use of the DNA database is personal identification, not fully tapping its data value. Data mining can provide assistance in conceptual formation and accuracy, exploration on regularity and pattern, modeling and the other useful knowledge. Using the methods of classification, estimation, prediction, affinity grouping, association rules and cluster analysis, data mining can fulfill a deep analysis of the intricate data in the DNA database, like the DNA profiles, the relevant information of cases, the background and behaviors of individual suspects. By resorts of cluster analysis, this paper attempts to obtain a preliminary analysis at multiple dimensions of time, space, type of crime. The analyzed data covered over 0.45 million criminal cases, 20 million individuals and 1 million matched reports, which were collected and produced in the past four years. The analysis is made up of three parts: the distribution of four kinds of crime (murder, robbery, theft, rape);the residence distribution of the offenders involved into the four kinds of crime;the situation of offenders resampled in the national DNA database. This study also carried out a SWOT (strengths, weaknesses, opportunities, threats) analysis on the application of data mining in the national DNA database. Data mining is an emerging technology of wide prospect. Its usage into the management and application of the national DNA database conforms to the open-mindedness of the information society, in favor of the improvement and development of the database itself. However, the above analysis is not perfect due to the limitations of underlying conditions. Through the combined application of the established means of data mining plus online analytical processing (OLAP), the attempts hereof can be continuously elevated along with the other analyses under dynamic and deep-reaching conditions. Therefore, the criminal time and space distribution will be defined more clearly, evolution and prediction of typical crime given more timely based on the personal and crime background, and the dynamics and early detection of high-risk criminal groups tracked more tightly with the DNA hunting and ID checking. Ideally, the DNA database can provide real-time, reliable and accuracy-high personal identification intelligence, showing its particular potential and value in the study of criminal pattern and dynamics, public security management decision and other involved aspects.