ABSTRACT
Serial numbers have forensic value as they help to identify firearms. While the serial numbers are mostly stamped on the metal parts of firearms, the characters on polymer parts involve non-serial number information such as caliber, brand, model, or proof marks, which also serve for identification purposes. The forensic evidence indicates that the polymer frames of firearms bearing non-serial number information are obliterated through heating and scraping. Although the destructive restoration techniques for polymers are well-documented, there is little theoretical and practical knowledge regarding the non-destructive restoration techniques applied on polymers. In view of this gap, this study aims to devise a non-destructive spectral technique to recover the obliterated characters on Polyamide 6. Considering its wide use on polymers, the numbering is carried out by hot stamping and the numbers are defaced through heating, scraping, and hammering both superficially and deeply at varying depths. Herein, we focused on imitating the manual obliteration techniques used by criminals instead of the deepness-controlled techniques preferred by previous studies. The samples are then viewed under the UV and IR lights in the Video Spectral Comparator 8000 for the first time. The results suggest that spectral imaging provided restoration to a good extent after heating and scraping which made the characters invisible at a relatively low depth of deformation compared to hammering. The recovery of characters with this novel technique brings a new perspective forensic marks examination literature by producing quick, successful and reliable results and facilitating reexamination by not harming the sample.
ABSTRACT
Detection of GSR particles potentially indicates that a person fired a gun or somehow involved to a shooting event. GSR on the shooter's hand, face, and clothing may disappear within hours and with sweat secretion, washing or cleaning to remove evidences. Due to its anatomical properties, ears are relatively protected; therefore, we aimed to identify GSR particles on ears, to compare its anatomical parts of ears, and compare ears with common GSR sampling sites, based on firing frequency. A 12-gauge semi-automatic shotgun was used. In the 4-week study, one shot in the first week, two consecutive shots in second week, three shots in third week, and five shots in fourth week were fired by six participants. Samples were taken from MAE, CA, and AAECA of both ears and common GSR sampling sites. The characteristic 3-component structure (Pb/Sb/Ba) of the samples was analyzed by SEM/EDX. Right CA was the most suitable area for sampling, which might be attributed to posture of body during targeting. Right ear was the most suitable area to take samples from CA or MAE in 3-shot group. Besides, left AAECA in 1- and 2-shot groups and the left MAE in 5-shot group were the most suitable areas for GSR sampling. In conclusion, ear seems to be a valuable alternative for detection of GSR particles, due to its complex anatomical structure potentially preventing loss of GSR with daily cleaning. Findings suggested that crime scene investigation teams and criminal laboratory staff should consider ear as a valuable alternative for GSR detection.
ABSTRACT
BACKGROUND: In this study, a 35 years old man was killed with the ricocheted shotgun pellets wounds from the asphalt road surface. The Public Prosecutor to define the ricochet point requested the ricocheted pellet pattern examination in two different ricochet distances. METHODS: The ten ricochet tests were performed for at 2 meters (point A) and 1 meter (point B) from the target, and the pellet distribution and pattern area were calculated using the gauss method. Then, the test and autopsy results were compared in the pellet number, calculated pellet pattern area and ricocheted angle. Furthermore, the similarity of the pellet number and the pellet pattern areas were examined using the two-tailed Mann-Whitney U test. RESULTS: In this study, 81 pellets recovered from the victim's body and the distribution pattern of pellets area was 2134 cm2. At the ricochet point A, the average number of pellets on the target was 82.1 and the distribution pattern of pellets area was 2700 cm2. At the ricochet point B, the average number of pellets on the target was 132.6 and the distribution pattern of pellets area was 4928 cm2. According to the two-tailed Mann-Whitney U test, there was low-level similarity (p<0.05 level Sig. 0.023; z=-2.424) on the pellet pattern area between autopsy and the ricochet point A. However, as regards the pellet number on the target, there was a similarity (p<0.05 level Sig. 0.481; z=-0.808) between autopsy and the ricochet point A. CONCLUSION: Test results showed that the pellet ricochet occurred two meters from the victim.
