Earticle

In this study, we have analyzed the current status and analysis of cases that have been requested to DNA analysis sector, Daegu institute, National Forensic Service (NFS), for the past three years. In 2014, a total of 2,036 cases were filed for DNA typing. In 2015, 2,626 cases were filed for it, an increase of 590 cases from 2014, and by 2016, 3,577 cases were filed for it, an increase of 851 cases from 2015. In case of urgent DNA typing, 27, 55, and 57 cases of DNA typing were commissioned in 2014, 2015, and 2016, respectively. We also examined the cases of total DNA typing request that we made in three years by 16 types of cases. In 2014, the number of DNA typing was high in the order of theft (38.7 %), rape (14.7 %), and unnatural death (I 1.2 %), and in 2015, theft (44.2 %), rape (1 4.2 %), and unnatural death (13.4 %). In 2016, which was the most frequently requested, many requests were made in order of theft (49.1 %), unnatural death (17.1 %) and rape (9.4 %). Of the types of cases that have been requested for DNA typing, DNA typing related to fraud, theft, unnatural death, and identification increased significantly every year. The increase in the number of DNA typing request related to the identity of the deceased and the identification is due to the increase in the number of autopsy cases, The increase in the number of DNA typing requests for evidence related to fraud or theft is considered to be due to the increase in life style crimes related to the economic downturn.

According to a case of sudden unexpected death of both asphyxiation and toxicity of gases at an open job site, a worker died near a landfill area after inhaling gases produced by decomposition. At the site of the accident, oxygen concentration was measured at 1.9 %, methane at 2.0 % and carbon dioxide at 21.7 %. Another case of unexpected death of asphyxiation occuned at an open job site of trash heap with an oxygen concentration at 6 %, carbon dioxide and methane concentrations at 17.2 %, 0.97 %, respectively. In cases of death of both asphyxiation caused by an acute lack of oxygen and carbon dioxide toxicity, it is necessary to perform accurate scene investigations to determine both the cause and manner of death.

This paper reports a murder case in which critical DNA evidence was provided through additional analysis of a bag strap that was used as the murder tool. Samples were first transferred from the surface of the bag strap by applying sterile cotton swabs before the whole bag strap was torn apart for further additional analysis. DNA was extracted from both kinds of sample, and the ratio of total to male DNA was quantified the success rate of this DNA type analysis was confirmed. In the samples from the cotton swab transfer, only the DNA type of the victim was detected with the autosomal short tandem repeat (A-STR) analysis, and no DNA type was detected with theY chromosome short tandem repeat (Y-STR) analysis. However, in the samples from the torn material, both the DNA type of the victim and that of the suspect were detected with the A-STR analysis, and the DNA type of the suspect was also detected with the Y -STR analysis. These results, suggest that more reliable data may be obtained by applying different sampling methods depending on the type and status of the evidence.

In many violent crime cases, a perpetrator assaults a victim with physical impact force (violence) using a part of the body or a hitting tool. Hence, violent crime cases are con·elated with impact force. Using various methods of impact force measurement, many studies have been conducted to develop impact force measurement sensors or devices. However, no study has been conducted on the correlation between physical behavior and impact force depending on the body characteristics in situations in which the impact force is applied using a part of the body or a hitting tool in the same posture; nor have studies considered the difference and range of the correlation. The present study was conducted to investigate the correlation between body characteristics (body weight and skeletal muscle content) and impact force by measuring the body characteristics of the subjects, applying impact force to an impact force measurement system using a part of the body or a hitting tool at the same height and in the same posture, and analyzing the resulting data. The results showed that linear regression plots of the acquired data depending on the subjects body weight were generally constant, but had some outlier values. The linear regression plots of the acquired data depending on the skeletal muscle content were very constant, indicating that the skeletal muscle content is a more important factor in the correlation with the impact force than is the body weight. In addition, the results also showed that gender is not significantly correlated with impact force.

In this study, the influence of explosion over-pressure caused by the rupture of bonded container LPG used as a propellant was calculated by using the Hopkinson's Scaling Law and the accident damage was estimated by applying the influence on the adjacent structures into Probit model. The overpressure calculated by probit model up to 4 m of interest is 55 kpa, This is an overpressure where all buildings are destroyed, The limit distance of structure damage was 15 m and the limit of glass damage was 45 m. As a result of this, in this study, 100 % of the explosion efficiency is applied, and the actual damage effect due to the explosion of the bonded container is considered to be less than the value calculated in this study.

In this study, we studied blood detection test and DNA typing from washed bloodstain samples. We considered the conditions of the washing time (using chlorine bleach), drying time and the type of detergent. Regardless of the drying time of the blood, bio detergent, non-bio detergent was found to be positive in all samples for the blood washing and STR (Short Tandem Repeat) was detected only in the samples dry at least 12 hours. Washing with chlorine bleach, blood detection test showed positive results only from the blood stains dried less than 4 hours, but STR was not detected in all samples, regardless of the drying time of the blood, and returned positive results in blood detection test and STR from all the samples that were dried for 24 hours and washed less than 10 minutes. Therefore, blood detection test and STR typing are influenced by various fac tors, including external factors such as the type of detergent, internal factors such as blood drying time. Thus it should be careful in judging if there is blood-stain or STR from the evidence prepared from an incident.

STR and SNP have been widely used genetic markers to confirm family relations. STR has been deemed very useful marker to confirm human identif ication and relations due to that everyone has different short tandem repeats (STRs) which is inhe rited indepe ndently. Des pite of weaker power of locus discrimination compared with STR, SNP features lower mutation rate (10·8) and binary polymorphism, which facilitate confirmation of family relations. In addition, applying next generation sequencing is now able to experiment larger number of SNP markers. In this study to determine relations of sibling, 17 STR and 169 SNP markers were used to see whether these markers have confidence to be used in the fi eld. 17 STR markers were detected in the full-sibling analysis and 140 SNP markers were analyzed among 169 SNP markers. When likelihood ratio value is more than 1, all true positive were detected (43 pairs), false negative were not detected and faJse positive pairs were more detected STR (47 pairs) than SNP (S pairs). Therefore FuJJ-sibJing anaJysis was efficient to use with the STR and SNP.

Blood marking starts from the outer border and dries to the center of blood. At this time, skeletoni zation s tain is formed when external force is applied. The experiment was carried out at a temperature of 20 ·c and a humidity of 55 %, and a skeletonization stain was formed with a blood volume of 24 11m and a height of 76 em and a force of about 12 N. The mean diameters were 12.12 mm, and the thicknesses were 3.80 mm. The drying in 10 minutes showed significant differences. When the ratio of the thickness and the diameter of the outline blood formed between I 0 minutes and 80 minutes is represented by the time equation, the error rate was from 0.5 % to 4.25 %. Therefore, when a person drops from the tip of a f inger or a knife in a standing position to produce a contour (about 76 em in height), the result of this experiment can be used to calculate the falling blood before the contour. It is expected that it will be able to judge the generation time.

The only cutTently available method of estimating blood origins of impact spatter bloodstain is a straight-line trajectory method based on the assumption that blood droplets travel in straight-line trajectories. However, since blood droplets actually follow a parabolic trajectory due to the effect of gravity and air resistance, there i s an urgent need for a method of estimating blood origins considering the parabolic trajectory in the analysis of impact spatter blood stain in bloodshed criminal incidents. In the present study, the equations of motion of blood droplets were analyzed to derive an estimation algorithm including a parabolic trajectory analysis, and a blood origin estimation program based on the algorithm was developed and validated. The results showed that the error rate of the software program developed in the present study, NFS Spatter Trajectory (NST), was lower than that of the conventional method by a maximum of 65 %. The NST software program developed in the present study may enable more accurate estimation of blood origins in the analysis of bloodstain patterns found in a crime scene, and replace expensive, imported software programs, giving an economic benefit to scientific investigations performed in South Korea.

1,2-IND, widely used as an amino acid reagent in detecting fingerprints on porous surfaces, shows outstanding performance among reagents developed after ninhydrin. This study examined the optimal optical conditions of 1,2-IND, a representative reagent that uses photoluminescence to detect latent fingerprLnts at crime scenes. The experiments found that the optimal conditions were a stimulus light of 505 nm and a 550 nm long pass fi lter. This was followed by a stimulus light of 505 nm and a 565 nm band pass filter, and a stimulus light of 530 nm and a 590 nm long pass fi lter. Investigation agencies are expected to benefit from using latent fingerprint detection with the optimal optical conditions of 1,2-IND provided in this study, in combination with camera shutter speed and aperture values.

Various types of bloodstain are found at criminal scenes in which bloodshed is involved. The impact angle from the ejection point of a falling bloodstain to the final surface may be estimated using the length of the long axis and the short axis of the bloodstain. The blood origin of an impact spatter bloodstain may be estimated by calculating the impact angle. The equation for calcul ating the impact angle may help to reconstruct a criminal scene. The conventional equation for calculating the impact angle is sina· = W/L, which is based on a general trigonometric function. Some studies have shown that the impact angle calculated using the conventional equation is different from the actual impact angle, but almost no study has been conducted to coiTect the equation. In the present study, an improved equation for calculating the impact angle was derived on the basis of impact angle experiments, and the error rates of the conventional equation and the improved equation were calcul ated. The improved equation is as follows W/L = 1.590 sin(0.009517a- 0.02887) A comparison of the impact angle calculated using the conventional equation and the improved equation with the actually measured impact angle showed that the error rate of the improved equation was significantly lower. Therefore, in a situation in which an impact angle of a bloodstain needs to be calculated for a criminal scene involving bloodshed, the improved equation provided in the present study may help to estimate the impact angle more accurately.