Earticle

It is crucial to detect blood on fabric as it can serve as important evidence for criminal investigation. However, when the blood volume is minimal or the fabric has been laundered, it becomes challenging to detect the bloodstain with the naked eye or even with the use of bloodstain enhancing reagents. Understanding the fabric's blood washing characteristics is essential when blood stains are not detected, as it helps determine the likelihood of fabric laundering. Factors influencing these characteristics include blood volume, fabric composition, detergent type, and water temperature used during laundering. This study focused on investigating the impact of fabric thickness on bloodstain washing using cotton fabrics. Nine fabrics of differing thicknesses, all 100% cotton, were selected. 100 μL of blood diluted 100 times in deionized water was deposited on each fabric, and then the samples were washed and dried. Subsequently, the fabrics were treated with acidic hydrogen peroxide (AHP), a bloodstain enhancing reagent, and any remaining blood was observed using a long pass filter (550 nm) under 505 nm light source illumination. The findings revealed that fabric thickness did not significantly influence blood washing characteristics.

In the last three years, from 2020 to 2022, there were 8,503 completed claims for damage to in-vehicle belongings across 10 insurance companies in South Korea. The distribution of completed claims belongings is 84.7% for car seats, 13.9% for golf clubs, and 1.2% for smartphones, with a total payout of approximately $4.5 billion over three years. Considering the severity of damage in completed claims cases, most of these accidents occur at low speeds, less than 20km/h. However, due to the lack of objective criteria for damage to belongings, some passengers are being compensated based on their claims, regardless of the severity of the accident. In this study, we conducted frontal and rear collision tests with a car equipped with belongings to reduce social disputes caused by the lack of standard regulation for damage to belongings. The car seats were mounted in the second row, the golf clubs were in the trunk, and the smartphones were in the driver's compartment. In order to objectively check the damage to the belongings, we asked a specialized testing organization to evaluate the performance before and after the collision test. After analyzing the performance evaluation results before and after the collision test, we found no change in the performance of the belongings, and no physical damage, such as deformation and breakage, was identified.

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.

Propofol is widely used for anesthesia and sedation due to its rapid onset and short half-life but has potential for abuse, leading to its regulation as a controlled substance in South Korea since 2011. Effective monitoring methods for propofol in urine are crucial due to its quick metabolism and excretion. This study presents an improved GC/MS method for detecting propofol by adjusting urine pH to acidic conditions, reducing nicotine interference. The method achieves reliable detection without derivatization or hydrolysis, with an LOD of 0.01 μg/mL and LOQ of 0.05 μg/mL. Testing on 10 urine samples showed no matrix interference, excellent linearity (correlation coefficient > 0.999), and satisfactory recovery rates (mean 107%). Precision and accuracy met validation criteria with within-run and between-run values within 15% and ±15%, respectively. Dilution tests confirmed minimal impact, maintaining 97－115% recovery. The effectiveness of excluding nicotine interference by adjusting pH was verified. Nicotine's interference was tested with QC samples at different pH levels, showing minimal interference at pH 4 compared to pH 9.5 (p<0.05). Acidic conditions improved propofol extraction and detection of hydroxylated metabolites. The study included 15 subjects (9 female, 6 male, aged 27－44), with an average propofol concentration in urine of 29.7 μg/mL (range 9.1－86.0). This approach is valuable for clinical and forensic toxicology applications, enhancing early detection of abuse and informing public health strategies.

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.

Ketamine analogues are one of the new psychoactive substances (NPS) that have recently been increasing in occurrence and causing social problems worldwide. One of these, 2-fluoro-2-oxo PCE, has also been detected more frequently in Korea recently. 2-fluoro-2-oxo PCE is known to exhibit hallucinogenic and dissociative effects by acting on N-methyl-D-aspartate (NMDA) receptors, similar to ketamine. In early 2024, a man who caused a traffic accident while driving, stated that he purchased and took ketamine. But 2-fluoro-2-oxo PCE was detected in his urine and seized items. In general, to detect narcotics in biological samples such as urine and hair, detection of parent drugs and metabolites is performed to exclude the possibility of sample contamination. However, for NPSs such as 2-fluoro-2-oxo PCE, metabolite research has not been sufficiently conducted. Therefore, we performed analysis of 2-fluoro-2-oxo PCE metabolites in urine using liquid chromatography/quadrupole time-of-flight mass spectrometry and MetabolitePilotTM software. The detected major metabolites of 2-fluoro-2-oxo PCE were a dehydrogenated form of the cyclohexanone ring (M163), an N-deethylated form (M144), and a form in which N-deethylation and dehydrogenation occurred simultaneously (M124). The metabolite of N-deethylated, hydroxylated, and glucuronide-conjugated form was also identified.

This study examined whether the multibody model and human model, commonly used in the reconstruction process of accidents related to the human body, can be applied to incomplete hanging. The following conclusions were obtained. The multibody model was able to successfully implement the results of Vladislav’s study, except for some body postures that could not be realized due to the model's inherent characteristics. By analyzing the load-bearing form according to the final posture of the deceased at the accident site and storing the site using a scanner for modeling, it appears that the process from the initial posture to the final posture in incomplete hanging can be successfully reconstructed. The human model, by first analyzing the load-bearing form according to the final posture of the deceased at the accident site and storing the site with a scanner for modeling, also seems capable of successfully reconstructing the process from the initial to the final posture in incomplete hanging. Additionally, it appears that the model can interpret the moment when blood flow is blocked.

Cannabis is strictly regulated under the Narcotics Control Act in Korea. Urine and hair samples are commonly used as biological samples to prove cannabis abuse. In general, to determine whether cannabis has been abused, 11-nor-9-carboxy -tetrahydrocannabinol (Δ9-THC-COOH), a major metabolite of cannabis, is analyzed to rule out the possibility of external contamination. Recently, 11-nor-8-tetrahydrocannabinol (Δ8-THC), an isomer of 11-nor-9-tetrahydrocannabinol (Δ9-THC) synthesized with cannabidiol (CBD), has also been abused in the form of electronic cigarettes, and its metabolite is 11-nor-8-carboxytetrahydrocannabinol (Δ8-THC-COOH). We attempted to analyze these cannabis metabolites in the nails to determine whether the subjects smoked cannabis. Method validation was performed using a Sciex 6500 LC/MS/MS for Δ8-THC-COOH and Δ 9-THC-COOH (THC-COOHs) in nails. The instrument conditions for THC-COOHs analysis were the same as those used for hair analysis, a column switching LC–ESI-MS 3 method. THC-COOHs were extracted by liquid-liquid extraction from digested nails with 1 N NaOH. The quantification of THC-COOHs and the identification of THC-COOH-d3 were performed using multistage fragmentation (MS3) with two transitions for THC-COOHs (m/z 343.1→299.1→245.2 and m/z 343.1→299.1→191.1) and one transition for THC-COOH- d3 (m/z 346.1→302.2→248.1). The quantifier ions are m/z 245.2 and 248.1. The calibration curve ranged from 0.05 to 20 pg/mg, R2 exceeded 0.999, and the LOD and LOQ of both components were 0.05 and 0.1 pg/mg, respectively. The accuracy and precision, matrix effect, recovery, and process efficiency were all within 15% of the CV values. Method validation results for THC-COOHs analysis for nails were not significantly different from those of hair, including the LOD and LOQ results. (Table 4.) Only one of the three authentic nail samples showed a positive result for Δ9-THC-COOH at a concentration of 12.29 pg/mg. These results indicate that since nails and hair can be analyzed under similar conditions, they may be useful alternatives to each other when collecting evidence of cannabis abuse.

With the rapid increase in electric vehicle penetration, fires are increasing every year. So far, the results of electric vehicle fire investigation have reached the limit of direct evidence in the face of the disappearance of tangible evidence due to thermal runaway of the large lithium-ion battery pack, an essential component of electric vehicles. In this study, we identified commonalities in various electric vehicle fire investigation cases along with a clear understanding of electric vehicles. If direct evidence cannot be prevented from being destroyed due to thermal runaway of the lithium-ion battery, The indirect evidence will remain in the vehicle's BMU(Battery Management Unit) just before the fire. By utilizing indirect evidence, such as available battery voltage information, to reduce the scope of inspection in large lithium-ion battery packs and to conduct diverse and precise inspections on direct evidence within a limited range, we suggest an efficient direction for electric vehicle fire investigation in the future(Oman, H. 2002).

Footprints are crucial forensic evidence found at crime scenes, possessing both class and individual characteristics that can aid in suspect identification. When a suspect assaults a victim, such as by kicking, shoe prints can be transferred onto the victim's clothing, providing decisive evidence amid conflicting statements between the victim and suspect. However, it is generally challenging to visually detect footprints on dark-colored clothing, and it is even more difficult to reveal prints on surfaces that are intricately patterned or multicolored. This study describes a method for revealing footprints formed on clothing surfaces by shoes contaminated with specific foreign substances like charcoal, using infrared(IR) Photography. In this experiment, a shoe artificially worn, scratched, or scuffed was dusted with charcoal powder and then contacted with various types of fabric to create footprints. These prints were photographed under infrared light in a darkroom and compared with photographs taken under typical indoor lighting conditions. The results suggest that footprints embedded with substances like charcoal can be effectively revealed on fabric surfaces using infrared Photography.

This study aims to determine the optimal YOLO algorithm for object detection performance in PreScan simulation. YOLOv4, the current model used, is compared with five versions of YOLOv8 (v8n, v8s, v8m, v8l, v8x). The analysis focuses on simulation time, initial detection distance, and continuous detection distance to assess the suitability of each version for practical applications. YOLOv8n, designed for speed and efficiency, demonstrated significant improvements in reducing simulation time, while YOLOv8x showed exceptional performance in terms of detection accuracy and consistency. The various versions of YOLOv8 each present unique strengths, with YOLOv8n excelling in speed and YOLOv8x in accuracy. YOLOv8m offered a well-balanced approach, making it particularly suitable for scenarios where both speed and detection reliability are crucial. The study highlights the potential benefits of adopting YOLOv8 models in PreScan simulations, emphasizing their ability to enhance object detection performance in the tested scenario. While further testing is needed to confirm applicability across various conditions, the results suggest that each version has unique strengths that could be leveraged depending on specific requirements. Overall, YOLOv8m is identified as the optimal choice for balanced performance in the current test scenario, ensuring both effective simulation and reliable object detection capabilities.

Enrofloxacin is a fluoroquinolone-based synthetic antimicrobial agent that exhibits potent bactericidal effects against gram-positive and gram-negative bacteria that infect aquatic animals. Thus, it is effective in treating bacterial infections in fish. However, antibiotic (enrofloxacin) residues in fish food or fish feed can threaten to human health in association with the development of antibiotic-resistant bacteria. In this case, the dead fish that may have included enrofloxacin residues was turned into fish feed and then sold to fish farmers. A total of 61 fish feed was asked to be examined for the presence of enrofloxacin. Therefore, this present study aimed to analyze enrofloxacin residues in fish feed by liquid chromatography quadrupole time-of-flight mass spectrometry(LC-QTOF/MS). For sample pretreatment, the QuEChERS(Quick, Easy, Cheap, Effective, Rugged, and Safe) method was applied to extract enrofloxacin from the sample and minimize matrix effects. As a result, enrofloxacin was detected in all the fish feed samples.