Forensic Analysis of Gunshot Wounds

Ballistic Injuries

• Unlawful use of firearms is increasing, readily available in many jurisdictions, regardless of possession laws
• Firearm injuries can be deliberate or accidental (e.g., hunting accidents)
• Firearm types include lethal barreled weapons, prohibited weapons (as per 1968 Firearms Act) and components/accessories designed to reduce the noise or flash
• Lethality is a legally determined issue for specific weapons
• Two main firearm types exist: smooth-bore (using pellets/shot) and rifled-bore (single projectiles/bullets). Airguns/air rifles use compressed gas
• Modern propellants (nitrocellulose, synthetic compounds) produce the gases propelling projectiles
• Muzzle velocity (speed of projectile exit) varies by weapon type (shotgun to military); energy is proportionate
• Shotguns are long-barreled, smooth-bore weapons using shot cartridges (single or double barrels)
• Rifled firearms (handguns, rifles) are long-barreled weapons for firing projectiles at targets over distance
• Revolvers use rotating cylinders and pistols use magazines. Rifle cartridges have a higher case to bullet ratio and larger propellant load

Firearms Injuries

• Injuries include smoke, flames, combustion gases, projectiles, propellant fragments, wadding

Evidence Recovery

• Forensic recovery examines projectile trajectory, range-of-fire, bullet/cartridge comparisons
• Firearm residue, shot patterns, smoke/powder-soiling are used for investigation

Injuries From Smooth-Bore Guns

• Pellets are propelled by gases from detonation, expanding at increasing distances from the muzzle
• Shot patterns are conical and expand as the shot travels from the muzzle to the target
• The closer the muzzle to the target the more concentrated the entry wound
• Contact wounds (when gun presses against skin) are circular. Smoke soiling and abrasion may be present
• Intermediate range (20-100cm): Smoke soiling/burning may occur with a central hole surrounded by pellet damage.
• Long range (> 1m) shows spread of shot, central hole decreases

Injuries From Rifled Weapons

• Bullets cause entry and exit wounds, sometimes retained in the body
• Muzzle velocity affects wound severity, and is related to both the mass/velocity of projectile and the trajectory, along with construction of the body tissues

Mass Disasters

• Mass disasters (natural or criminal) need triage to prioritize patients' needs
• Triage uses colours (Red for immediate, Yellow for delayed, Green for minor) for rapid classification
• Triage should respect individual medical needs, not other criteria
• Forensic recovery requires proper documentation, recording and preservation of evidence

Air Weapons/Unusual Projectiles

• Airguns/air rifles use compressed air to propel projectiles
• Injuries vary by design but entry wounds resembling bullet wounds usually do not exit the body
• Non-standard firearms use a variety of mechanisms for the discharge of projectiles

Miscellaneous Firearms and Weapons

• Kinetic Energy Devices (KEDs) are impact devices intended to deter, not cause serious harm
• KED impacts should target less vulnerable areas
• Various projectiles are used from KEDs
• Stud guns, humane killers, bows/crossbows also cause injury with varying severity and characteristics

Determination of Accident, Suicide, or Murder

• Forensic investigation focuses on factors such as timing, weapon access, location of wounds, and weapon location in determining nature
• Identifying intent can be challenging given the various factors involved, considering the nature of injuries and the circumstances

Identification of the Living and the Dead

• Identifying the deceased requires consideration of multiple factors
• Age estimation in the living is important for legal and safety processes
• DNA profiling, dentition (teeth), fingerprints, morphological characteristics, tattoos/piercings are all helpful for identification.