Earticle

STR typing of crime scene evidence is currently contributing to solving various cases. In a autopsy case, the identity of the body is confirmed by collecting blood and comparing the STR typing results of the deceased with those of the family. This study, the rapid DNA extraction reagent was used to purify DNA from autopsy samples, blood and costal cartilage, and the effect of the rapid DNA extraction reagent on STR type was examined by comparing it with standard DNA. As a result of the experiment, the average DNA concentration using the rapid extraction reagent was purified to 0.277 ng/㎕ for blood and 0.069 ng/㎕ for costal cartilage, which met the recommended DNA concentration of 0.050 ng/㎕ for the STR amplification kit. The DNA degradation index was confirmed to be a maximum of 1.703 for blood and 0.660 for costal cartilage. In the case of STR type detection, DNA types were detected in all blood and costal cartilage samples. In the balance comparison of the values of heterozygous loci, there was no significant difference in the analysis values compared to the standard DNA samples, with 3 loci in blood, 6 loci in costal cartilage, and 6 loci in 007.

This study proposes and implements a blockchain based system to ensure the integrity of digital evidence. Digital evidence plays a crucial role in legal disputes and criminal investigations, However conventional centralized systems are vulnerable to data tampering and loss. To address these challenges, this research designs a system that guarantees the integrity of digital evidence throughout the processes of collection, storage, and verification by utilizing a private blockchain. This paper begin by examining blockchain and various consensus algorithms, followed by a detailed description of the implementation methods and processes of the proposed system. The system employs Ethereum-based GoQuorum to construct the private blockchain. Also, the QBFT consensus algorithm used in this network provides high security and fast processing speeds. By developing the smart contract, we enabled the storage and retrieval of the generated hash value of digital evidence on the blockchain. Our System verifies integrity by comparing the hash value stored on the chain with the hash value of the original image. Consequently, the blockchain-based integrity verification system has contributed to enhancing the reliablility of digital evidence and has improved both efficiency and security in legal proceedings.

This paper dealt with the power and risk evaluation of pipe type homemade firearms using black powder and steel ball, based on actual incident case that occurred in Republic of Korea(2016 Opeasan shooting incident). As a result of experiment, although pipe type firearms has a very simple and basic structure, it showed threatening power. It was confirmed that the main effect on the power of a pipe type firearms is the amount of black powder charged. The pipe type homemade firearms in the experiment used a 6.7~11.5 ㎜ steel ball as projectile, and it is judged to be powerful enough to kill ordinary people even if only 1.5~2.5 g black powder is used. In addition, depending on the amount of black powder, it not only has the possible hunting power of a very large animals(227~998 ㎏), but also has kinetic energy that is more 1.5~2.5 ratio higher than the industrial pistols. According to the result of experiment, the power of homemade firearms is variable and difficult to predict, so if similar case occurs, it is considered that the same response as an actual firearms incident should be shown. In addition, it is considered that related organization have to continuously maintain preparedness for this type of shooting terror or incident.

Even though vehicles are important means of transportation in modern society, they are accompanied by lots of traffic accidents. Sudden unintended acceleration(SUA) is supposed to be one of them. This study investigates the effect of lubricating system of vehicle equipped with turbocharger on SUA from two perspectives which are the quality and quantity of the lubricating oil system. The diluted lubricating oil with diesel oil didn't show deteriorating effect on the consistency of turbocharger at normal quantity. However, excessive quantity of oil showed dramatic effect on engine performance of exhausting white smoke with noise and vibration. This malfunction was thought to be from the flow of lubricating oil through blowby gas ventilation system into combustion chamber. Lest the problem should happen, lubrication management of vehicles is thought to be necessary for both sides of the quality and quantity of the lubricating oil.

In many countries, firearm-related homicides are prevalent due to less stringent gun control regulations compared to Korea, leading to extensive research on bloodstain patterns caused by firearms. However, in Korea, where kitchen knives are commonly used in homicides due to their accessibility, research on the bloodstain patterns they create is significantly lacking both domestically and internationally. This study aims to distinguish between spurt bloodstains produced by a moving bleeding part (e.g., wrist) injured by a kitchen knife and swing cast-off bloodstains resulting from the swinging of a kitchen knife. The findings revealed that spurt bloodstains formed in the direction of the movement for both straight and curved trajectories. In contrast, swing cast-off bloodstains formed a straight trajectory when the knife was swung straight, but spread radially when the knife followed a curved path. These results are expected to contribute significantly to crime scene bloodstain pattern analysis, aiding in crime reconstruction and in determining the intent of the perpetrator.

When washing fabrics with blood on them, it is important to know the factors that affect the washing characteristics of blood. To investigate this, the authors prepared different thickness fabrics of 100% cotton, cotton/polyester blend(65%/35%), cotton/polyester blend(35%/65%), and 100% polyester. The cloths were then contaminated with blood, washed with detergent, and visualized with acidic hydrogen peroxide(a blood sensitive reagent) to observe the amount of blood retained. The results showed that the blood washed out better with more washing cycles, and the blood washed out better with a lower percentage of cotton. However, regardless of the blend, the thickness of the fabric did not seem to have any correlation with the degree of blood washing. On the other hand, if the fabric surface was coated, the blood washed well.

In order to simplify and reduce the cost of the analysis process for reference samples, STR typing using direct PCR buffer was confirmed. To select an efficient buffer, STR typing was performed using two kinds of buffers. As a result of comparing the STR full profile detection rate and peak height through the heat treatment-based rapid extraction method of the reference samples, it was confirmed that STR GO! was more efficient than Prep-n-Go. In addition, when using commercially available STR and Y-STR analysis kits (GlobalFiler, PowerPlex Fusion, Y23), it was found that there was no problem in result analysis even if the PCR reaction volume for DNA extracted with STR GO! was reduced to 10 uL. However, the detection rate of STR profiles decreased in DNA that had passed time after extraction. To overcome this, the dilution ratio of the PCR amplification product was adjusted and it was confirmed that there was no problem with STR typing even 4 weeks after extraction. This study is expected to be of great help in simplifying and reducing costs of STR typing for reference samples.

Fingerprints containing organic and inorganic UV-blocking ingredients on various paper surfaces(copy paper, kraft paper, leaflets, newspapers) were developed using ultraviolet imaging and 1,2-IND/Zn, and then the effect of UV-blocking ingredients on fingerprint detection was studied. As a result of observation using ultraviolet imaging, fingerprints containing organic sunblock ingredients appeared relatively clearer than fingerprints containing inorganic sunblock ingredients. In addition, it was found that the more the surface fluoresces, the more the sunblock ingredient blocks the surface fluorescence, making the fingerprint be detected more clearly. As a result of enhancing the same fingerprint to 1,2-IND/Zn, fingerprints containing organic sunblock ingredients were developed slightly brighter than fingerprints containing inorganic sunblock ingredients. Being aged after deposited, sunblock ingredients spread over the surface and the fingerprint was not detected with ultraviolet imaging, but amino acid component contained in sweat does not spread and the fingerprint was visualized with 1,2-IND/Zn.

Traffic accidents are caused by various causes such as human factors : carelessness of vehicle drivers, etc, vehicle defects : braking system defects, etc and environmental factors. It is required to identify whether the accident is caused by careless of the driver or vehicle defect because of the legal responsibility of the driver. This case is an accident which the vehicle named chairman drove backwards on the road after refueling at a gas station and crashed into the wall of a building 200m away, and the driver claims it was a sudden acceleration accident due to a vehicle defect. Through the trace of the accident vehicle, trace formed on the driver's shoes, vehicle inspection and CCTV analysis, it is determined that the accidents are caused by carelessness of the driver who press the accelerator by mistake. If a similar case occurs in the future, it is thought to it can be used to determine the cause of the accident.