Earticle

We studied the transfer and persistence of the fibers on the blade when a blade penetrated two layers of fabrics. To do this, a cotton plain weave fabric with a thickness of 0.29 mm was covered with a cotton plain weave fabric with thickness of 0.11 mm, 0.18 mm, 0.52 mm, 0.76 mm or 1.50 mm each. The two layers of fabrics were stabbed once with a knife and then evaluated the amount of fiber transferred to the blade. The results showed that fibers from the lower layer fabric were wiped off by the upper layer fabric, leaving less than 50% of the original amount transferred to the blade. The thicker the upper layer fabric, the more fibers from the lower layer fabric were wiped off. However, the amount of upper layer fabric fibers transferred on the blade did not correlate with the thickness of the upper layer fabric.

Wood is a tissue produced by the hypertrophic growth of the cambium in woody plants. Along the mesh's holes in the cambium at the transverse section, nutrients and moisture pass through in the longitudinal direction. At the radial section, which is a cross-section along the radial direction, the pit structure acts as a passage for the horizontal movement of nutrients and moisture to adjacent tissues. This structure varies in shape with different species and could be used as a tool for the identification of wood. This study investigates the identification of carbonized wood found in a damaged vehicle and that obtained near a fireside by observing their pit structure with an electron microscope. After washing and drying the two carbonized samples and subsequently observing them with an electron microscope, the similarity in their pit structures was evident. This similarity suggests that the two samples belong to the same species. Typically, identifying wood species requires a significant amount of time and labor for sample pretreatment. Overcoming these challenges, a method using an electron microscope could identify the species through carbonized wood.

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.

ketamine(KT), a NMDA receptor antagonist synthesized in 1962, exhibits rapid onset of action and short duration of effect, making it useful in a variety of medical applications. However, KT is a narcotic whose number of abusers has been rapidly increasing over the past 10 years due to the dissociative effect, known as 'K-hole', which causes symptoms such as delirium, short-term memory, cognitive impairment, and hallucinations. In some cases, even when KT is administered illegally, KT and its metabolites may not be detected in urine, making it difficult to confirm whether KT has been administered. However, in this study, in addition to the previously reported metabolites, presents the metabolite detected at highest concentrations in urine. After a simple urine pretreatment of a 25-year-male KT abuser, the urine sample was analyzed using liquid chromatography-mass spectrometry(LC-MS/MS) and liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS/MS). As a result of quantitative analysis of KT and its metabolites in LC-MS/MS analysis, the concentrations of KT and its metabolite norketamine(NK) were 1.94 mg/L and 2.57 mg/L, respectively. Analysis of KT metabolites using LC-QTOF-MS/MS positive mode with Sciex's MetabolitePilotTM software, we identified the metabolite detected at the highest concentration in urine, and also identified the glucuronide conjugated metabolite after di-oxidation in the NK structure. By analyzing the metabolite identified in this study, aimed at confirming KT administration through urine, it is possible to conduct a more comprehensive analysis even when reported metabolites of KT are not detected.

EDR (Event Data Recorder) is part of the ACU (Airbag Control Unit) function installed in vehicles. EDR data includes pre-crash and post-crash data. Pre-crash data is recorded within 5 seconds from AE (time 0) at 0.5-second resolution and displays vehicle speed, engine RPM, throttle opening, brake pedal activation, accelerator pedal position, and steering angle, etc. Using these EDR data, traffic accident investigations can become more objective and scientific. In this case, by compared the EDR data stored in the event of an accident with the actual accident situation through accident cases, we will find out what to be careful in analysis the cause of the accident.

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.

An electrical fire caused by contact failure leaves unusual features such as an excessive oxidation of copper wire, which is an electrical singularity mainly found in wire connections. Previously, in order to determine the Cu2O growth in wire connections, detecting the thinning shape of the wire, confirming the presence of easily broken reddish-purple oxide, and analyzing the component ratio of each element through SEM-EDS(Scanning Electron Microscope-Energy Dispersive Spectrometer) were performed. In this study, we suggest a method to confirm the Cu2O growth in wire connections through X-ray diffraction patterns and component ratio analysis obtained from contact failure samples taken from fire scenes. The presence of Cu2O was clearly confirmed in each sample, and it is expected to provide a reliable results in determining the cause of fire.

Various bloodstains can be observed at the crime scene of bloodshed such as murder. Among them, projected bloodstains are bloodstains that can be caused by a large amount of blood projected due to damage to the arteries, which are major blood vessels, and can be a key basis for behavior reconstruction in crime scene. These bloodstain can be created due to partial or complete amputation of the artery or venous blood vessels, and their shape and distribution can be formed differently depending on the heartbeat, diameter of the blood vessels, blood pressure, gravity, etc. Therefore, a bloodstain pattern analysis(BPA) experiment is needed, and the development of a device to reproduce the bloodstain is necessary. In this study, we designed device can reproduce projected bloodstain by copying human heart and blood vessel. We used pump, power-supply, silicone hose, potentiometer, manometer to design the device. Experiment was carried out that reproducing the projected bloodstain, depending on the size of blood vessels. The projected bloodstains were similar to the bloodstains that were reported. The device can reproduce similar projected bloodstains observed in crime scene. So, we purpose the device for reproducing projected bloodstain for crime scene reconstruction. Though, there is a difference between the actual heart and blood vessels, so it is believed that follow-up studies are needed to supplement them.

In this study, we investigate the phenomenon where momentarily melted copper is scattered from the power source side to the load side during a short-circuit in electrical wiring, caused by arc sparking at the fault. This results in different short-circuit shapes on the power source side compared to the load side. Additionally, we theoretically analyze physical phenomena such as the Lorentz force acting on the electric wire during a short-circuit. By sharing these experimental and theoretical findings, we aim to better understand the mechanism of short-circuit formation and utilize this knowledge to pinpoint specific ignition points in fire investigation contexts.

Footprint evidence is essential in crime scenes as it is commonly found and can reveal the type and size of the suspect’s footwear. Detailed characteristics such as wear marks, impressions, and scratches can determine if a shoe matches the crime scene. Unlike fingerprint evidence, where Edmond Locard set a minimum characteristic point standard in 1914, footprint analysis lacks a clear quantitative foundation for identification determination. This study aims to establish a quantifiable basis for comparing the reliability of footprint and fingerprint identification by referencing established methods in fingerprint analysis. Based on previous research by Stone and Lim, which quantified the probability of identification for footprints, we conducted a comparative analysis with fingerprint standards. Our findings indicate that the selected footprints, which had 17 to 18 characteristic points, were considered identical based on fingerprint criteria. This comparison suggests that applying similar quantitative measures to footprints as those used for fingerprints can enhance the objectivity and reliability of footprint identification determinations in criminal cases, potentially aiding judicial decisions.

To analyze the causes of traffic accidents such as school zone accidents and right-turn accidents, considering the driver's blind spots is crucial to clearly understand the driver's risk perception at the time of the accident. However, the field of view presented in emotional dashcam footage differs from the actual driver's field of view, making it difficult to accurately reflect the driver's field of view and blind spots using conventional black box footage or literature-based driver field of view analysis methods. Therefore, this study proposes an analysis technique utilizing eye-tracking technology to scientifically and objectively determine the driver's field of view limits. The analysis was conducted on three real traffic accident cases using eye-tracking technology. The results confirmed significant differences between the field of view observed in black box footage and that of drivers wearing eye-tracking devices, highlighting the importance of considering individual driver characteristics in accident analysis for more objective and scientific conclusions.

Helium is widely utilized colorless and odorless inert gas, which poses a risk of hypoxia-induced asphyxiation when encountered in high concentrations, as it diminishes the partial pressure of oxygen during respiration. Accurate detection of helium from autopsy sample is essential for forensic investigations to ascertain the cause of death in suspected cases of helium asphyxiation. Conventionally, Gas Chromatography with a Thermal Conductivity Detector (GC-TCD) is employed for headspace gas analysis of autopsy samples. Nonetheless, the efficacy of this method is often compromised by helium's low reactivity and the minimal residual presence in samples, further complicated by hydrogen interference resulting from putrefaction. This study introduces a novel preprocessing technique that utilizes an electric arc to initiate a reaction with oxygen, effectively eliminating hydrogen from the headspace gas and thus enhancing the detection of helium. Experimental validation revealed that a 5-minute preprocessing period could remove 95% of hydrogen, while a 10-minute treatment achieved a 97% reduction. The successful detection of helium in putrefied autopsy samples underscores the effectiveness of this method, offering a promising approach to improve helium detection in forensic contexts.