2 FirearmsFirearm - a device designed to propel a projectile through a cylinder/ barrel.The force needed for the propulsion of the projectile is usually generated by the pressurized gas produced by the combustion of a small amount of explosive material known as propellant in an enclosed space.
3 AmmunitionIt is a general term to denote cartridges, grenades, mines, rockets and artillery.Cartridge‘complete round used for firing after insertion in to a barrel ‘.
4 Smooth bore weapon cartridge is usually consisted of a case with a metal base, propellant, projectile (shot), cap/primer and wads. The shot usually consists of multiple metal balls.Rifled bore weapon cartridge is made of metal alone. The two main components of the cartridge are the bullet (the projectile) and the case.The rifled bore weapon cartridge has a length (height) and a caliber/ bore.
5 Firearms can broadly be divided in to two main types. Smooth bore weaponsRifled bore weapons
6 Smooth Bore Weapons Types of Smooth Bore Weapons seen in Sri Lanka Breech loading shot gunBreech loading shot pistolMuzzle loading shot gunMuzzle loading trap gun (‘Kandan thuwakkuwa’, ‘maruwela’, bandina thuwakkakuwa’) – A country made shot gunMuzzle loading shot pistolsSwan-off shot gun (‘Galkatas’) – An improvised modification of shot gun
7 A shot gun could be a muzzle loader or a breech loader. Ammunitions do not come in a compact form.Components of a shot should be refilled before each shotBreech loaderAmmunition is always a standard factory made (shot gun cartridge).
8 A shot gun is of two types Single barreledDouble barreledWhen double barreled, they are usually positioned side by side or rarely one below the other.
9 Rifled weaponsA rifled weapon has a barrel with multiple fine grooves which make the bullet to spin around its own axis when it leaves.This gyroscopic movement will minimize the wobbling of the bullet enabling it to keep its track to find the target thus enhances the accuracy.
11 Identification of Firearm Injuries A firearm injury is usually a perforating laceration.The identification of an injury as a firearm injury is based on the following criteria;Familiarityb. There is an entry, track and an exit.The characteristic features of a firearm injury - abrasion collar, burning, blackening and tattooing may be present. d. The history by eye witness – circumstantial evidence
12 Effects and Components of Firing A bullet or a collection of pellets (shot)Wads (if available)Residue of primer (burnt, partially burnt and unburnt)Residue of propellant (burnt, partially burnt and unburnt)Residue lubricantsFowling present in the barrel due to previous shotCompressed gas containing sootFlameHeatNoise
13 Medico-Legal Issues in the Investigation of an Alleged Firearm Death Is it a firearm injury or not?If it is a fire arm injury, what is the nature of the firearm and ammunition?How many fire arms have been used?How many shots have been fired?
14 What is the sequence and direction of firing? What are the circumstances? Are they accidental, suicidal, homicidal or done in self defense?Recovery of spent cartridges and other trace material from the scene.Have the spent cartridges been shot from this specific gun? (Specific identity of the weapon)Identity of the assailant.
15 Identity of the deceased. Identity of the entry, the path inside the body and respective exit wounds.The cause of deathTime since deathPossibility of volitional activity.Reconstruction of the event.Approximate distance of firing.
16 Entry Wounds and Exit Wounds Entry WoundsUsually smaller, circular or oval (approximately the size of the missile)Abrasion collar and contusion collar are present.Burning, blackening and tattooing may be present.Muzzle mark may be present.Margins are inverted.Clothes are driven inward in the track.Pinkish discolouration of the wound may be present due to Carbon monoxide.Beveling of the inner table of the skull.
17 Abrasion collar absent. Burning, blackening and tattooing absent. Exit WoundsTypically large and irregular. (but could be smaller. Ex: in contact and near contact entries)Abrasion collar absent.Burning, blackening and tattooing absent.No muzzle mark.Margins everted.Tissues from the track protruding out.No carbon monoxide.Beveling of the outer table of the skull.
18 Range of Fire Smooth Bore Weapons Smooth Bore WeaponsContact range – Muzzle mark on the skin around the entry wound. Burning, blackening and tattooing with pink discolouration (cherry pink colour due to CO).Near contact – No muzzle mark but with evidence of local explosive effect and burning, blackening and tattooing.Within 1 foot – single entry with burning, blackening and tattooing.Within 2 feet – single entry with blackening and tattooing only.Within 3 feet (1 yard) – single entry with tattooing only.Beyond 3 feet – tattooing is absent and the dispersion of the pellets begin and there will be individual entries caused by the dispersing pellets either singly or in combination.
19 Rifled WeaponsContact range - Muzzle mark on the skin around the entry wound. Burning, blackening and tattooing with pink discolouration.Near contact – No muzzle mark but with evidence of local explosive effect and burning, blackening and tattooing.Within 6 to 12 inches - Burning, blackening and tattooing.12 to 18 inches – Blackening and tattooing only.18 to 24 inches – Tattooing only.Beyond 24 inches – Tattooing absent.Extreme ranges – The entry is large and ragged.
20 Direction of FireThe direction of fire can be determined by the following factors.The shape of abrasion collar, contusion collar, burning, blackening and tattooing;Circular –fired at right angleElliptical – fired at an angleThe beveling of the skull;Equal on all sides – fired at right angleMore on one side – fired at an angleShelving and undercutting are seen when fired at an angle.
21 Circumstances of FireHomicidalSuicidalAccidental
22 SuicideHomicideUsually single injury (may be multiple) with one fatal injury.Multiple injuries on various parts of the body with more than one fatal injury.Weapon found close to the body usually gripped in hand in cadaveric spasm.Weapons not found with the body or the surroundings.Entry wounds are found in accessible sites.Entry wounds can be at any place of the body.Entry wound in an elective site such as temple, mid forehead, roof of mouth, under the chin, precordium.Not an elective site.Range always contact or near contact unlessa mechanism is used to pull the trigger.Range beyond arms reach (distant range)Associated with psychiatric disturbances and previous para- suicidal attempts.Associated with enmity, robbery, rivalry etc.Usually no eye witnesses.Eye witnesses’ accounts
23 Medico legal investigation History – reference to type of gun, number of shots, range and relative positions of victim and assailant.Visit to the sceneIdentification of the bodyPreliminary proceduresPhotographyX – rays
24 Collection of trace materials (missiles and wads, soot, burnt and unburnt gunpowder from the clothing and the entry wounds, gun powder from the hands of the weapon-user -useful in suicidal firearm injuries)Clothing – for burns, powder residues and infrared photographyGeneral external examinationSpecific external examination – entry and exit woundsInternal examination (track including injuries to internal organs and tissues/ recovery of pellets, bullets wads etc.)Laboratory investigations by the Forensic Ballistics expertDocumentation and reporting