Revealing Weapon Impacts on Clothes Using Reaction Reagents for Amino Acids / 대한법의학회지

If we analogize any external physical force applied to victims of crimes involving violence, it would be possible to not only presume the mutual action between victims and suspects but also deduce more facts related to the cases. Therefore, in this study, defining the phenomenon of amino acid compounds in sweat spreading into clothes as impact marks, experiments using ninhydrin, 1,8-dizafluoren-9-one (DFO), 1,2-indanedione-zinc (1,2-IND-Zn) were conducted to determine developmental variations through change over time, which was not performed in previous studies. A 5-week period was set up including first damage as a variation factor, and materials in each action were developed using certain reagents. The level of specimen development depending on the change over time was identified. Thus, no changes were observed at each initial level of development.

A Study of Impact on Head and Neck Using Human Volunteer Low-Speed Rear Impact Tests / 대한법의학회지

Whiplash injury in low-speed traffic accidents are not objectively verified by medical equipment, thereby creating scope for misuse, which has resulted in huge social losses worldwide. The aim of this study was to examine the influence of low-speed vehicular rear-impact collisions on middle-aged men, and to analyze the head and neck injury criteria for the symptomatic human volunteers. Data was examined from the results of 50 dynamic sled tests, originally performed by Hong et al. (2012). In the previous tests, 50 men aged 30~50 years were exposed to an impulse equivalent to a bumper-to-bumper rear collision under medical supervision, and no resulting whiplash injury was identified. In this study, for 6 subjects who experienced dull aches over their bodies, head injury criteria (HIC15) and neck injury criteria (N(km)) were calculated according to the accelerations, forces, and moments at the occipital condyle measured by motion capture system. Although there were no changes in magnetic resonance imaging findings in all subjects at the pre-/post-test orthopedic examination, 6 subjects revealed mild aches around the shoulder, back, or lumbar area, and their symptoms disappeared within 2 days. The head and neck injury criteria, HIC15 (3.086 +/- 2.942) and N(km) (0.077 +/- 0.064) were obtained, and the maximum HIC15 and N(km) were found to be significantly lower than the critical injury assessment reference values (HIC15: 700, N(km): 0.3). Moreover, even though 2 subjects were exposed to the same level of change of velocity (7.9 km/h), each N(km) was significantly different (0.179, 0.057). One can therefore conclude that N(km) can vary according to voluntary movements in the human subject.

Measurements and Comparative Considerations of Velocities of Primary Bloodstain Spatters using a High Speed Camera / 대한법의학회지

Bloodstain pattern analysis is a forensic discipline that reconstruct events of a crime scene by analyzing sizes, shapes, distributions, positions of bloodstains. Bloodstain pattern can be classified into the low velocity, medium velocity, and high velocity system. Velocities in this system represent the velocity of the wounding agent (the force applied) and not to the velocity of the blood in flight. Thus there is no reference system about the velocity of the blood in flight in the existing bloodstain classification system. Applying bloodstain pattern analysis to the real crime case, we needed to have the reference system of velocities of impact spatter, cast-off spatter, and expectorate spatter. Therefore we measured the velocities of these spatters using high speed camera and we analyzed the results. In this experiments the average velocity of impact spatter that generated by swinging a hammer with all experimenter's strength at the pool of blood is about 4.7 times faster than that of swing cast-off spatter that generated by swinging a red-wat hammer with all experimenter's strength, and about 3.9 times faster than that of expectorate spatter that generated by emitting blood from the mouth with all experimenter's strength. The velocities of cast-off spatter and expectorate spatter, however, showed similar distributions. Our experiments that measure the velocities of droplets of blood spatters in flight under the specific conditions that generated at fastest speed can give some reference to the classification system of velocities of bloodstains which is not distinct up to now, as well as some real bloodshed crime cases.

A Study of Similarities Between Bloodstain Pattern Analysis and Fire Investigation In Point View of Event Analysis / 대한법의학회지

Crime scene reconstruction is the use of scientific methods, physical evidence, deductive and inductive reasoning and their interrelationships to gain explicit knowledge of the series of events that surround the commission of a crime. Event analysis is the method of crime scene reconstruction. As disciplines of crime scene reconstruction, bloodstain pattern analysis and fire investigation have many common points. Comparing bloodstain pattern analysis with fire investigation in point view of event analysis helps us to further understand crime scene reconstruction as well as bloodstain pattern analysis and fire investigation themselves. We study event analysis and apply it to cases and we seek similarities and differences between bloodstain pattern analysis and fire investigation by analyzing the methodology of both of them. In a fire scene, the point with the greatest damage is the point where the fire burned longest, which is likely to be the origin. In bloodstained scenes this approach is reversed. The greatest bloodshed point is most likely the ending point of the incident and is likely at or near the point where the bloodshed started. Above this, there are other similarities between them. Mastering the crime scene reconstruction requires long time hard training. Thus if the fire investigation experts or arson experts among crime scene investigators join the field of bloodstain pattern analysis(or reverse), then there will be many synergy effects to both of them.