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FM6.1-2,FM7.1-2,FM14.11 | Firearm, Blast & Regional Injuries — PBL Case

CLINICAL SETTING

You are a forensic medicine resident called to assist in the autopsy of two bodies recovered from a collapsed riverside warehouse that was reportedly the scene of an explosion followed by gunfire. The first body (Victim A) is a 34-year-old male with multiple injuries. The second body (Victim B) is a 29-year-old male found 8 metres from the blast epicentre. Police have recovered three 9mm cartridge cases, residue of an improvised explosive device (IED), and a steel crowbar near the bodies. A detained suspect claims 'an accidental gas explosion' was the only event.

Trigger 1: Victim A — Autopsy Findings

Victim A: Height 170 cm, body weight 72 kg. External findings: (a) A wound on the right cheek, 0.8 cm diameter, round, punched-out margin with a concentric abrasion collar 0.2 cm wide; no soot, no tattooing. (b) A wound on the left cheek, 2.1 cm, irregular, everted margins, no abrasion collar. (c) Bilateral tympanic membranes intact. (d) No other external injury. Internal findings: Track of haemorrhage from right cheek through the oral cavity to the left cheek. Skull X-ray: single bullet track, no fragmentation.

DISCUSSION POINTS

  • Classify each cheek wound as entry or exit, citing specific morphological features. What firing range is suggested by the absence of soot and tattooing?
  • Reconstruct the bullet trajectory through the head. Based on the entry/exit positions, what can you infer about the relative position of the shooter to the victim? Is this consistent with 'defensive posture' or 'execution position'?
Click to reveal Trigger 2: Victim B — Blast and Fragmentation Injuries (discuss previous trigger first!)

Trigger 2: Victim B — Blast and Fragmentation Injuries

Victim B: Found 8 m from blast epicentre, against a concrete wall (tertiary throw distance noted in scene report). Autopsy findings: (a) Bilateral tympanic membrane perforations. (b) 23 irregular metallic fragment wounds on the anterior trunk and thighs, each <1 cm, with blackening and irregular margins. (c) Contusion haemorrhages throughout both lung parenchymata, confirmed on histology as alveolar haemorrhage with barotrauma. (d) T10 vertebral compression fracture. (e) No gunshot wounds detected. Radiology confirms multiple metallic fragments. No exit wounds from fragments.

DISCUSSION POINTS

  • Categorise each injury finding (tympanic perforation, fragment wounds, pulmonary contusion, vertebral fracture) into the primary/secondary/tertiary/quaternary blast injury framework. Justify each classification.
  • The suspect claims only an 'accidental gas explosion' occurred. The fragment wounds show blackening. What forensic investigations on the fragments and wound tracks would confirm whether this was an IED (military-grade explosive) versus a domestic gas explosion, and would help quantify proximity to the blast?
Click to reveal Trigger 3: Reconstruction and Medico-Legal Opinion (discuss previous trigger first!)

Trigger 3: Reconstruction and Medico-Legal Opinion

Scene report: The warehouse measures 15 × 10 m. The IED remnant is located in the NW corner. Victim A is found in the SE corner (15 m away). Victim B is found 8 m from the blast, on the east wall. The steel crowbar shows blood and hair matching Victim A on one end. Three 9 mm cartridge cases are located near the NW blast point. The steel joists of the roof collapsed AFTER the blast (confirmed by fire investigator timeline). Police wish to know: (i) Was Victim A killed by the gunshot or the blast or the structural collapse? (ii) Could the gunshot have been accidental? (iii) What is the sequence of events?

DISCUSSION POINTS

  • Using the autopsy findings, determine the cause of death for Victim A. Assess whether the single through-and-through gunshot wound at intermediate range is consistent with accidental discharge, suicide, or homicide. What features of the wound and scene most strongly support one hypothesis?
  • Construct a likely sequence-of-events timeline using all available evidence (wound morphology, blast injury categories, scene layout, crowbar evidence). What additional evidence (GSR, histology, ballistic trajectory rods, CCTV) would you request to complete the reconstruction?

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [FM6.1] What is the classification of firearms and ammunition relevant to medico-legal reporting, and how do calibre and gauge relate to wound morphology?
  2. [FM6.2] What are the distinguishing morphological features of entry vs exit gunshot wounds, and how does firing range alter wound characteristics (contact → distant)?
  3. [FM6.2] What are the four categories of blast injury, their underlying mechanisms, and the characteristic pathological findings of each category?
  4. [FM7.1] How are gunshot wound trajectories reconstructed at autopsy, and what anatomical findings determine the direction of fire?
  5. [FM14.11] What is the legal framework for evidence collection, chain of custody, and documentation in firearm homicide investigation in India?