Distinguishing homicides and suicides in firearm fatalities: the role of skeletal trauma analysis
De La Paz, Jade S.
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The work of an international team of forensic experts led to the final determination that Salvador Allende, former Chilean president (1970-1973), committed suicide by firearm during the military coup against his socialist government on September 11, 1973. Included in the final report was the anthropologists’ skeletal trauma analysis documenting the gunshot trauma to the skull as consistent with the passage of a high velocity projectile under the chin and through the cranial cavity. The anthropological report was part of a multidisciplinary effort to finally address the questions surrounding the manner of Salvador Allende’s death, and to eliminate speculations that he was killed by the military. Although it is not the role of the anthropologist to determine manner of death in a forensic case, expertise in osteology and the biomechanics of high velocity projectile trauma to bone may contribute to the pathologist’s final conclusions about manner of death in firearm fatalities. Previous research looking at variation between homicides and suicides in firearm fatalities has used soft tissue trauma analysis and autopsy reports to identify common characteristics specific to these manners of death. They have found that anatomic location of entrance trauma, bullet direction, number of shots, and range of fire are important factors in understanding this variation. Anthropological research has not explored these differences as they are expressed on the skeleton, however; knowledge of variation in skeletal gunshot trauma, between self-inflicted and other-inflicted gunshot wounds, can better equip anthropologists to report pertinent information that can lead to accurate determinations of manner of death. The current study explores the factors of anatomic location of entrance trauma, bullet direction, and number of shots, with additional consideration to fracture severity and fracture patterns, in place of range of fire. The William M. Bass Donated Skeletal Collection and the Antioquia Modern Skeletal Reference Collection provided a total sample of 15 suicide and 19 homicide cases for this analysis. This research found that localized entry sites to the front and right sides of the head and to the chest were common in suicides. Entries to the left and front sides of the head and to the posterior side of the head and body were common in homicides. Further analysis of sequence of shots and entry sites revealed that the front of the head, common in both homicides and suicides, was more common in secondary gunshot wounds in homicides. Bullet directions common in suicides were right to left through the sagittal plane, and anterior to posterior through the coronal plane. The left to right direction through the sagittal plane was most common for homicides, whereas the anterior to posterior and posterior to anterior directions through the coronal plane were almost equally represented in homicides. Further analysis of sequence of shots and bullet direction revealed that the anterior to posterior direction was more common in secondary gunshot wounds in homicides. The transverse plane did not show statistically significant differences between homicides and suicides for either the inferior to superior or superior to inferior directions. For number of shots, homicides more commonly expressed multiple gunshot wounds and suicides more commonly expressed single gunshot wounds. Fracture severity analyses revealed that the presence of tertiary fractures (concentric fractures) in entrance wounds was more common in suicides. The presence of secondary fractures (radiating fractures) as the most severe fracture in entrance wounds was more common in homicides. These results suggest that fracture severity is higher in suicides, based on the amount of kinetic energy dispersed at impact, although it is unclear what factor influences these differences (range of fire, type of firearm, caliber of bullet, etc.). There was also a significant difference between homicides and suicides in fracture patterns for both entrance and exit wounds. These findings are based on a small sample and should be considered with caution, especially for use in a forensic setting. Further research is crucial to better understanding the variations seen in this study. Specifically, sequencing of shots should be further explored for its utility in distinguishing homicides and suicides as well as providing a better understanding of multi-shot cases. Additionally, more research should be conducted on fracture severity and fracture patterns with specific consideration to the factors that influence the variation seen between homicides and suicides.
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