brand logo

Reconstructing a ‘hit-and-run’ road accident in Sri Lanka

14 Jul 2022

  • Forensic academic notes need for advanced assessment of injuries and use of biomechanics 
BY Ruwan Laknath Jayakody Since extensive internal injuries along with bizarre external injuries are common in fatal road traffic accidents, meticulous injury interpretation and event and injury reconstruction would be useful in determining the sequence of events, while the development of biomechanics in order to make useful conclusions – such as the positive identification of the perpetrator and the offending vehicle – is essential. These observations and recommendations were made in a case report on “Injury interpretation and the reconstruction of events in a victim of a ‘hit-and-run’ road traffic incident” which was authored by H.T.D.W. Ariyarathna (attached to the Sri Jayewardenepura University’s Medical Sciences Faculty’s Forensic Medicine Department) and published in Sri Lanka Journal of Forensic Medicine, Science, and Law’s 13 (1) in June, 2022. A medico-legal expert (forensic pathologist) is obligated to address any medico-legal issues that arise following violent deaths. The investigation of a crime scene by investigating police officers and the available post-mortem findings are often enough to reconstruct events during most routine medico-legal investigations. However, there are some instances in which extensive analysis and interest is required in order to address medico-legal issues.  Incorrect reconstruction has grave consequences in the medico-legal field, as it may effectively exonerate the perpetrator while concluding that an innocent person is guilty. Events occurring during a victim-vehicle collision can be complicated. Therefore, A. Giorgetti, G. Cecchetto, C. Giraudo, E. Quaia, A. Viero, G. Viel, and M. Montisci’s “Reconstruction of the dynamic in a fatal traffic accident with prolonged dragging of the victim” notes that such events should therefore be analysed and interpreted with caution.  Due to the scarcity of biomechanics and its applications in Sri Lanka, scene investigation and scientific observations were used to reconstruct the events in this case. It is not infrequent to sustain bizarre patterned injuries during road traffic accidents. As a result, it is possible that certain injuries are overlooked. This case report is an instance where the reconstruction of each injury in a logical manner proved to be of major benefit in revealing an atypical run-over injury that was not initially suspected by the investigating police officer. Case history  A 49-year-old male was discovered dead by the side of the road along with his damaged motorcycle. This was suspicious of a hit-and-run accident. There were no eyewitnesses or closed circuit television (CCTV) footage of the incident. However, a sudden moderately loud noise had made a neighbour visit the scene. He had noticed the unresponsive victim lying on the road. He was wearing a helmet with no other protective wear. The victim’s severely damaged motorcycle was located by the side of the road. The cause of death was determined to be blunt force trauma to the head, chest, and spine sustained by the motorcyclist as a result of a vehicular collision. The incident was described as a run-over injury by a heavy vehicle of which the driver had driven away without informing the Police (hit-and-run road traffic injury). The injury pattern was consistent with those sustained due to acceleration and deceleration (head injury), and being run-over (upper back of the chest) by a heavy vehicle. The run-over injury was unequivocally diagnosed by considering the torn areas, the faint grease and dust marks on the back of the T-shirt, and by the underlying injuries that were unexplained otherwise. The large injury in the form of an abraded contusion that extended across the back of the upper chest was initially not explainable during the post-mortem examination. However, a degree of suspicion as to why the undamaged, peculiar patterned injury was seen within the contused abrasion was the trigger to analyse the injuries extensively. If the injury over the back of the chest was not analysed and interpreted as a whole, this deduction would have been impossible. Because the case at hand involved a hit and run accident, it was necessary to reconstruct the dynamic events that occurred and to interpret the injuries in order to identify the implicated vehicle and the driver.  Ariyarathna was unable to interpret or provide an opinion on the injury situated on the upper back of the chest. It did not show features of a primary impact injury or secondary injury. However, subsequent to injury documentation, the internal dissection was initiated without any interpretation of the external injuries. The internal examination revealed multiple posterior rib fractures, lung lacerations and contusions, and vertebral column damage, thus arousing suspicion of a run-over injury. There was no other convincing explanation for the severity of the injuries that he had sustained on his chest.  An examination of the scene was conducted retrospectively by Ariyarathna. This did not result in any convincing evidence to ascertain the reason for the spared skin in the upper mid-back of the chest. Given that those injuries were sustained as a result of being run-over, Ariyarathna was then compelled to look for possible tyre marks on his body and clothing. The mark observed on the back of the upper chest which did not have a viable explanation at the outset of the post-mortem examination was then subjected to an in-depth study.  If the mark was caused as a result of a run-over accident, it was necessary to determine the reason for the absence of typical tyre marks and the reason for the sparing of an oval shaped area of skin in the centre or either side of the midline. The absence of typical tyre tread marks on the alleged run-over injury was attributed to the vehicle likely having wasted tyres. The T-shirt that the deceased was wearing may have also partly contributed to the absence of tyre-tread marks. The absence of injuries over the upper mid-back of the chest should also be explained as the second query that was encountered during the medico-legal investigation. However, the reason for that was not clear and required further meticulous observations and reasoning. The second to eighth ribs had been bilaterally fractured in two locations, resulting in the formation of two vertical imaginary lines on each side. The symmetrical rib fractures in the second to eighth ribs allowed for the formation of a separate bony flap that could be pressed into the posterior thoracic (located in the upper and middle part of the back) cavity while the tyre ran over the upper back of the chest in the prone position. The fractures at the first and second thoracic vertebrae may have facilitated the indentation of the bony flap, thereby preventing skin contact with the running tyre. Another medico-legal issue that needed to be addressed was the vehicle’s travel direction. The concentration of dust and grease marks on the victim’s clothes, which decreased from the left to the right while the victim was prone, was used as evidence, per D. Dolinak, E. Matshes and E. Lew’s “Forensic pathology: First edition” and H.L. Beddoe’s “Hit-run murders: Examination of the body”. The severity of the skin injury was also gradually reduced from his left to the right while he was in the prone position. By considering those two facts, Ariyarathna was able to provide an opinion that the offending vehicle was moving from the left to the right of the victim while he was in the prone position. It is the duty of the forensic pathologist to provide useful information after the post-mortem examination to the investigating Police officer to continue his investigation. On this body, there were no primary or secondary impact injuries or secondary injuries. Instead, a run-over injury was identified. At the end of the post-mortem investigation, Ariyarathna informed the investigating police officer that there has been a component of being run-over in addition to it being a hit-and-run incident.  The estimated minimal width of the tyre from one sidewall to another of the offending vehicle and the direction of travel of the vehicle was also determined (the width was 15 cm and the vehicle moved from the left to the right of the victim while he was in the prone position at the scene). The Police were further informed that no paint flakes or any other trace evidence was collected from the dead body. On inquiry by the Police, the possibility of being run-over by two vehicles was ruled out due to the uncomplicated nature of the injuries confirmed by the judicial medical officer and the direct testimony from the neighbour who rushed to the scene immediately upon hearing the moderately loud noise. The technical examination of the motorcycle that was conducted by the Police investigators along with the findings of the run-over injury, revealed that the offending vehicle had collided with the motorcycle, imparting significant kinetic energy to his body, in turn causing him to be thrown off from his seating position, resulting in him being run-over by the same vehicle. In this case, the dynamic events were reconstructed using knowledge from the basic sciences and empirical studies. The width of the tyre-mark injury provided information about the tyre’s dimensions. As per the dimensions of the injury situated over the back of the chest, the width of the tyre from the sidewall to the opposite sidewall was around 15 cm. It provided a clue or evidence to trace the offending vehicle.  A medico-legal expert must suggest the dynamic actions that could have occurred during a road accident. The dynamic movements of the victim that could have occurred during the incident and the impact should also be considered with great care while arriving at conclusions.  However, there is no standard scientific procedure to cross-check or double-check the conclusions reached based on the reconstruction of events in this case. Further, there is no other convincing explanation for this case scenario within the limits of the examination. As a result, it was concluded that the bony flap supposedly created by the moving tyre on the upper back could have resulted in the atypical run-over injury.


More News..