• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.626-643
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• 2023

As mobile forensics has emerged as an essential technique, the demand for technology development, education and training is increasing, wherein images are used. Academic societies in South Korea and national institutions in the US and the UK are leading the Mobile Forensic Image development. However, compared with disks, images developed in a mobile environment are few cases and have less active research, causing a waste of time, money, and manpower. Mobile Forensic Images are also difficult to trust owing to insufficient verification processes. Additionally, in South Korea, there are legal issues involving the Telecommunications Business Act and the Act on the Protection and Use of Location Information. Therefore, in this study, we requested a review of a standard model for the development of Mobile Forensic Image from experts and designed an 11-step development model. The steps of the model are as follows: a. setting of design directions, b. scenario design, c. selection of analysis techniques, d. review of legal issues, e. creation of virtual information, f. configuring system settings, g. performing imaging as per scenarios, h. Developing a checklist, i. internal verification, j. external verification, and k. confirmation of validity. Finally, we identified the differences between the mobile and disk environments and discussed the institutional efforts of South Korea. This study will also provide a guideline for the development of professional quality verification and proficiency tests as well as technology and talent-nurturing tools. We propose a method that can be used as a guide to secure pan-national trust in forensic examiners and tools. We expect this study to strengthen the mobile forensics capabilities of forensic examiners and researchers. This research will be used for the verification and evaluation of individuals and institutions, contributing to national security, eventually.

• Biomedical Science Letters
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• v.24 no.1
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• pp.35-42
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• 2018

Postmortem interval (PMI) is very important in the crime scene investigation. However, it is very difficult to estimate of the interval since death after a decomposition. Recently, there have been various studies on the postmortem interval since a decomposition. In particular, the total body score (TBS) and accumulated degree days (ADD) used to estimate the postmortem interval after a decomposition. This study was conducted with the aim of applying the TBS and ADD to estimate the postmortem interval in real forensic caseworks. In first murder case, TBS was 12 and ADD value was 132, respectively. An estimated time of PMI was around 23:00 on June 21, and the suspect's statement was 01:20 on June 22. Our estimated interval since death and the suspect's statement for the PMI differ by only 2 hours and 20 minutes. In second forensic case, TBS was 3 and ADD value was 55, respectively, an estimated time of PMI was around 02:26 on September 23. The suspect's statement was 10:30 on September 23. Our estimated time and the suspect's statement for the PMI differ by 8 hours. In these cases, we were able to have confirmed the feasibility of TBS and ADD on the real forensic cases. Overall, our finding suggested that the quantitative method could be used to produce PMI estimates that are accurate to within days or even hours.

• Biomedical Science Letters
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• v.29 no.4
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• pp.302-313
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• 2023

Y chromosomal short tandem repeat (Y-STR) markers have been developed continuously to complement forensic DNA analyses and population genetic studies. Initially, we collected data from previously reported Korean population Y-STR haplotype studies on 1133 individuals. We then conducted a marker expansion analysis using a dataset from the Y-STR Haplotype Reference Database (YHRD), covering up to 29 Y-STRs, referred to as Ymax. Additionally, we examined the impact of rapidly mutating (RM) Y-STRs included in this expanded marker set on the discrimination capacity. We observed that marker expansions both with (0.9896), and without (0.9510), RM Y-STR improved the discrimination capacity. Subsequently, we focused on 16 individuals belonging to seven distinct groups sharing identical haplotypes. These particular haplotypes had been previously identified among 476 unrelated males using 23 Y-STR markers from the PowerPlex^® Y23 System. We expanded the marker panel up to Ymax to explore how discrimination improved with an expansion of Y-STR markers for these 16 individuals. Among the expanded markers, DYS627, which had high discriminatory power, had a high mutation rate (1.10 × 10^-2) and high gene diversity (0.83). In contrast, DYF387S1 displayed high gene diversity (0.95) but a relatively low mutation rate (2.80 × 10^-3). We propose that these findings will be valuable in the selection of suitable Y-STR markers, depending on the objectives of forensic analyses. Additionally, the presence of frequently observed Y-haplotypes in Korean population will facilitate statistical interpretation in Y-STR DNA profiling.

• Analytical Science and Technology
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• v.11 no.3
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• pp.1033-1043
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• 1998

• Biomedical Science Letters
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• v.26 no.4
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• pp.275-287
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• 2020

Since its introduction in the forensic field, quantitative PCR (qPCR) has played an essential role in DNA analysis. Quality of DNA should be evaluated before short tandem repeat (STR) profiling to obtain reliable results and reduce unnecessary costs. To this end, various human DNA quantification kits have been developed. Among these kits, the PowerQunat® System was designed not only to determine the total amount of human DNA and human male DNA from a forensic evidence item, but also to offer data about degradation of DNA samples. However, a crucial limitation of the PowerQunat® System is its high cost. Therefore, to minimize the cost of DNA quantification, we evaluated kit performance using a reduced volume of reagents (1/2-volume) using DNA samples of varying types and concentrations. Our results demonstrated that the low-volume method has almost comparable performance to the manufacturer's method for human DNA quantification, human male DNA quantification, and DNA degradation index. Furthermore, using a reduced volume of regents, it is possible to run 2 times more reactions per kit. We expect the proposed low-volume method to cut costs in half for laboratories dealing with large numbers of DNA samples.

• Biomedical Science Letters
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• v.28 no.3
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• pp.157-169
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• 2022

DNA typing is the typical technology in the forensic science and plays a significant role in the personal identification of victims and suspects. Short tandem repeat (STR) is the short tandemly repeated DNA sequence consisting of 2~7 bp DNA units in specific loci. It is disseminated across the human genome and represents polymorphism among individuals. Because polymorphism is a key feature of the application of DNA typing STR analysis, STR analysis becomes the standard technology in forensics. Therefore, the DNA database (DNA-DB) was first introduced with 4 essential STR markers for the application of forensic science; however, the number of STR markers was expanded from 4 to 13 and 13 to 20 later to counteract the continuously increased DNA profile and other needed situations. After applying expanded STR markers to the South Korean DNA-DB system, it positively affected to low copy number analysis that had a high possibility of partial DNA profiles, and especially contributed to the theft cases due to the high portion of touch DNA evidence in the theft case. Furthermore, STR marker expansion not only contributed to the resolution of cold cases but also increased kinship index indicating the potential for improved kinship test accuracy using extended STR markers. Collectively, the expansion of the STR locus was considered to be necessary to keep pace with the continuously increasing DNA profile, and to improve the data integrity of the DNA-DB.

• Journal of Information Science Theory and Practice
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• v.12 no.1
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• pp.39-59
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• 2024

An online social network is a platform that is continuously expanding, which enables groups of people to share their views and communicate with one another using the Internet. The social relations among members of the public are significantly improved because of this gesture. Despite these advantages and opportunities, criminals are continuing to broaden their attempts to exploit people by making use of techniques and approaches designed to undermine and exploit their victims for criminal activities. The field of digital forensics, on the other hand, has made significant progress in reducing the impact of this risk. Even though most of these digital forensic investigation techniques are carried out manually, most of these methods are not usually appropriate for use with online social networks due to their complexity, growth in data volumes, and technical issues that are present in these environments. In both civil and criminal cases, including sexual harassment, intellectual property theft, cyberstalking, online terrorism, and cyberbullying, forensic investigations on social media platforms have become more crucial. This study explores the use of machine learning techniques for addressing criminal incidents on social media platforms, particularly during forensic investigations. In addition, it outlines some of the difficulties encountered by forensic investigators while investigating crimes on social networking sites.

• Journal of Science Criminal Investigation
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• v.11 no.3
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• pp.210-217
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• 2017

In the forensic microbiology laboratories, microorganism analyses from food are requested. There have been several cases of Bacillus cereus isolated from the samples requested to the National Forensic Service. B. cereus is an important pathogenic bacterium which can cause food-borne outbreaks. Therefore, we isolated B. cereus from anchovy aekjeot recently requested for microbial examination and identified using MSId based on the 16S rDNA sequence and real-time PCR method. We also conducted PCR for detection of diarrheal toxin genes and an emetic toxin gene and found the presence of nheABC, bceT and entFM diarrheal toxin genes in the B. cereus isolate. There are several clinically important food-poisoning bacteria that should be noted during inspection. In particular, B. cereus can cause food poisoning even when cooked foods are ingested, because B. cereus forms endo-spore which confers strong environmental resistance and heat resistance to the bacteria, and the bacterial emetic toxin also has heat resistance. Here we highlight the importance to distinguish clinically important bacteria such as B. cereus from food specimens, and we expect this study will provide procedures for identification of B. cereus and detection of the bacterial toxin genes for future cases in the forensic microbiology laboratories.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.1
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• pp.95-102
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• 2015

Smartphone is very useful for use in the real world, but it has been exposed to a lot of crime by smartphone. Also, it occurs attempting to delete a data of smartphone memory by anti-forensic tools. In this paper, we implement an anti-forensic tool used in the Android. In addition, tests to validate the availability of the anti-forensic tool by the Oxygen Forensic Suite that is a commercial forensic tool.

• Biomedical Science Letters
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• v.27 no.2
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• pp.105-110
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• 2021

Short Tandem Repeats (STR) analysis which characterized by genetic polymorphism has been widely used in the forensic genetic fields. Unfortunately, mutation occurred in various STR loci could make it difficult to interpret STR data. Thus, the mutation rate of STR loci plays an important role for the data interpretation in human identification and paternity test. To verify the mutation of the STR loci in the Korean population, 545 trio sets (father, mother, and child) were analyzed with two commercial STR kits that include the 23 autosomal STR loci (D1S1656, TPOX, D2S441, D2S1338, D3S1358, FGA, D5S818, CSF1PO, D7S820, D8S1179, D10S1248, TH01, D12S391, VWA D13S317, D16S539, D18S51, D19S433, D21S11, D22S1045, SE33, Penta E and Penta D). As a result, 36 mutations were observed in 14 STR loci. The types of mutation were also classified by the increase or decrease of the alleles. The overall mutation rate was 1.4×10^-3, and the paternal mutation rate was four times higher than that of the maternal. This study will provide more detailed criterion for human identification by the mutation rate of STR loci in the Korean population.