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Forensic Ballistics.pptx
This document summarizes key aspects of forensic ballistics including: 1. Ballistics is the study of firearms, ammunition, and their effects. Forensic ballistics deals with investigating firearms/ammunition and the injuries/medico-legal issues they cause. 2. Ballistics is divided into internal, external, terminal, and wound ballistics. Internal ballistics examines what happens inside the firearm during discharge. External ballistics examines what happens after discharge until impact. Terminal and wound ballistics study the projectile's motion upon impact and the resulting injuries. 3. Key parts of firearms include the chamber, barrel, magazine, and types. Rifled firearms have grooves cut into the barrel to
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Forensic Ballistics.pptx
- 1. Forensic Ballistics Dr NikitaPrabhakaran Assistant professor
- 2. Ballistics • It isthe study of firearms and ammunition
- 3. Forensic Ballistics • Dealswith 1. the investigation of firearms and ammunition 2. Injuries caused by it and 3. the medico-legal problems associated with it
- 4. Internal ballistics Externalballistics Operation of a firearm and the movement of the projectile Inside the firearm Study of events -after the discharge of the projectile from the firearm - Till it reaches the target
- 5. Terminal ballistics vswound ballistics • Terminal ballistics motion of the projectile in the target • Wound ballistics study of the injury caused
- 6. Parts of afirearm
- 7.
- 8. • Cartridge pre-assembled firearm ammunition • Magazine- ammunition storage and feeding device for a repeating firearm
- 9. Types of firearms •Rifled firearms • Smooth bore firearm
- 11. Rifling • The internalsurface of the barrel has been scored by a number of spiral grooves • More common number is 6 • Sometimes there can be microridges • Projectile is usually called a bullet
- 13. • Examples areREVOLVERS RIFLES PISTOLS
- 14. • Projecting ridgesare called lands • The deep portions are called grooves • Distance between diagonally opposite lands is called calibre
- 16. • In USAit is measured in Inches 0.22 • In Europe expressed in millimetres
- 17. Need for rifling??? •Spinning action to the bullet • Stabilizes its flight/ straight trajectory path • Prevents wobbling/ tumbling • Penetrative power increased • Increases accuracy and range (NEET PG)
- 18. How to increasethe range of firing?? • By increasing the length of the barrel • So according to that : – (a) Short barrel firearms – (b) Long barrel firearms
- 19. Pistols and revolvers •Short barrelled rifled firearm
- 20. Pistols Catridges in avertical magazine When fired, empty catridge case falls at some distance away New catridge slips into the breach automatically by spring action Should be reloaded again Hence, “ Semi-automatic”
- 21. Revolvers • In ametallic revolving cylinder • After firing, the cases remain there • After one round, it should be loaded manually again
- 22. • AK47 • AK74 • Automatic rifles fire using gases of the previous
- 23. SHOT GUN • Singlebarrelled/ double barelled • Smooth bored weapons • Projectile- pellets
- 24.
- 25. Choking??? • Reduction ofdiameter at the muzzle end of the barrel. • Reduces the dispersion of pellets and holds the pellets together for a longer distance • Can be non- choke bore/ choke-bore
- 27. Paradox guns • Actuallyshots guns • But with rifling at the muzzle end
- 28. GUAGE • Indicates thediameter of the barrel • Determined by no: of lead pellets which can be made from one pound of pure lead • Exactly fitting the bore of the shotgun
- 29. • Smaller thegauge greater the diameter • Ranges from 10 to 28.
- 30. CATRIDGE • Consists ofa metallic case in which: • Projectile pellet/bullet • Propellant gunpowder • Primer gives the impulsive spark to ignite the propellant
- 32. Functioning?? • Pulling thetrigger and released • Striker goes and hits the percussion cap • Releases heat • Primer inside the percussion cap ignites • Explodes the gunpowder (propellant) • Projectile is propelled
- 33. Purpose of wad?? •Plastic/ paper disc • Acts like a piston • Propells the pellets together
- 34. Primary marking andsecondary marking • In all rifled firearms, • Cartridges are usually larger than the barrel • (for perfect obturation)
- 35. • Thus whena bullet passes through it, • the markings of the lands on the bullet –PRIMARY MARKINGS –Reveal the manufacturer of the gun • Unique markings typical to the weapon –SECONDARY MARKINGS
- 36.
- 37. Pellets??? • Lead largepellets buckshot/ mould shot • Single large pellet in shot gun is called SLUG • Smaller than bore diameter • Base- hollow • End-pointed
- 38. Bullet??? • Are ofdifferent sizes and shapes • Varies from one firearm to another
- 39. Dum-dum bullet • Itis open at the nose and is covered with a lead jacket. • It expands on hitting the target • Hence produces a larger wound
- 40. Frangible bullets • Theybreak into multiple pieces when they enter the body • Here, matching with the test bullet is difficult
- 41. Tandem bullets (Piggytail/ piggy back bullet) • It means two bullets come out from a single firing shot • Causes: • (a) defective ammunition where one gets stuck in the barrel and on subsequent firing the new bullet comes along with the previous one • (b) duplex/ tandem catridge manufactured in a single catridge there will be two bullets one behind the other
- 42. MLI One entrance woundand two exit wounds Or Two entrance wounds Or No exit wounds
- 43. Ricochet bullet • Bulletchanges its direction by striking on some surface or object Bullets can get deformed Speed is dampened and hence placed superficial on the body
- 44. Types • External ricochet •Strikes an intermediate object before entering the body • Entrance wound may be deformed • May show foreign bodies from the striking object • Usually in inferior weapons
- 45. • Internal ricochet –Occurs inside the body
- 46. Medico-legal significance • Incase of external ricochet, unintentional firing may be used as a defence • The entrance wound will be larger than the expected • Velocity is reduced and may produce a keyhole injury on the skull • Gutter fracture on the skull • Grossly deformed, identification is difficult.
- 47. Souvenair bullet • Bulletsremain in the body silently • Sometimes, they are made to remain like that • Because intervention might cause more damage. • Seen encapsulated by fibrous tissue. • c/c lead poisoning may be seen.
- 49. Gun powder (Propellant) •Black powder- classic one • Smokeless powder • Semi-smokeless powder
- 50. Black powder • PotassiumNitrate (75%) gives oxygen for burning • Charcoal (15%) fuel • Sulphur helps in ignition • Coarse /fine FG, FFG, FFFG • 1gm 3000 -4000cc • CO, CO2, N2, H2S
- 51. Smokeless powder • Singlebase- Nitrocellulose • Double base- Nitrocellulose (60%) • Nitroglycerine (40%) • 1gm 12,000 to 13,000 gas
- 52. Semi- smokeless powder •80% black powder • 20 % smokeless powder • Triple baser Nitrocellulose+ nitroglycerine+ Nitroguanidine
- 53. Wounds produced byFirearms
- 54. In any firearminjury, there will be (1)Entrance wound (2)Exit wound (3)Track of the fire-arm inside the body
- 55. Classification • 1. Woundscaused by shotgun • 2. Wounds caused by rifled firearms
- 56. Flame = 30cm Smoke= 45 cm Unburnt gun powder= 60 to 80cm
- 57. Wounds caused byshotgun Product of firing Distance up to which it travels Injury caused Flame 30 cm Burning Smoke 45 cm Blackening Unburnt powder grains 60-80 cm Tattooing Pellets move together Up to 2 metre Single hole Pellets spread >2 metre Multiple holes Wad travel Up to 5metres Metallic fouling due to metals expelled by the discharge
- 60. Wiping ++ • Tattooing doesn’t go • Smudging/blackening goes off • Metal fouling does not go
- 61. Contact shot • Explosiveinjury + Gross destruction of tissues • Entrance wound: • Muzzle imprint + Cherry red discoloration • Burning, smoke and soot inside the track
- 62. Specific appearance ofContact Shot • Muzzle/ recoil imprint mark • Back spatter • Blowback phenomenon or blast effect- – Cruciate/ stellate/ragged laceration – Especially if there is a bone underneath
- 63. • Clothes werepresent soot and burns on the clothes +++ • Exit wounds- depends on the area of injury • If its head, lesser space for the gas to expand hence mutilated • If it is chest or abdomen, a round entry wound and an exit wound may be there
- 66. Close range <30 cm • Large entrance wound • Burns singeing of hair • Blackening / smudging due to smoke • Tattooing in the periphery
- 67. 30- 45 cmrange • No burning • Blackening and tattooing
- 68. > 45 cm- 80cm • Only tattooing and central hole
- 69. 1- 2m • Singleentrance wound with irregular margins • RAT HOLE APPEARANCE
- 70. > 2 metres •Pellets begin to spread • Central hole • Surrounded by multiple wounds • Scattered wounds
- 71. > 4 metres •Scattered holes • No central hole • All of comparable sizes
- 73. > 5metres • Wadwould produce a typical irregular wound • Dispersion of wounds caused by individual pellets.
- 74. Exit wounds froma shotgun • Contact and close range shots pellets do make exit wound • But otherwise they stay within the body • Thinner body parts like limbs– will have exit wounds
- 75. Wounds caused byrifled firearm • Entrance wound • Contact wound – stellate/ cruciate wound • burning, blackening, tattooing inside the track
- 77. Close shot • Burning •Blackening • Tattooing around the entrance wound • Entrance wound usually circular • edges- inverted
- 78. • Abrasion collar/contusion collar • the abrasion caused around the entry wound due to the spinning action • Grease collar/ bullet wipe • dirt and grease on the bullet
- 79. NOTE • Abrasion collarand dirt collar • characteristics of an entrance wound
- 80. Absent abrasion collar •Entry wound on palms and soles • Ricochet bullet
- 81. • Diameter ofthe bullet entrance wound + abrasion collar
- 82. • Near shot •Upto 8 cm burning +++ • Upto 15 cm burning -, tattooing +,blackening + • Upto 60 cm burning -, blackening -, tattooing + • Distant shot • > 60 cm abrasion collar and grease collar alone
- 84.
- 85. SMOOTH BORE CONTACT SHOT CLOSE NEARINTERMEDI ATE DISTANT RANGE < 1 metre 1-2 metre 2-4 metre >4 metre > 5 metre Stellate wound Circular wound Irregular wound RAT HOLE Central hole large + satellite holes Individual pellet holes Wad wound + individual pellet wounds Muzzle imprint ++ single Single Multiple wounds Multiple Burns + blackening+ Tattooing + In the track Burns + - upto 30 cm Blackening +- upto 45 cm Tattooing +-upto 80 cm Around the wound ------ -------- ---------
- 86. Rifled firearm CONTACT SHOT Pointblank Close shot (Range of flame) Near range (Range of gunpowder) Long range (beyond that range) < 8cm <60 cm Stellate wound Muzzle imprint Circular entrance wound Abrasion collar Circular entrance wound Abrasion collar Wound < bullet Abrasion collar Burns Blackening Tattooing (in the track) Burns + Blackening+ Tattooing+ Burns – Blackening— Tattooing ++ Burns-- Blackening-- Tattooing ---
- 87. Note : if thereis external ricocheting abrasion collar may be absent Blackening, burning , tattooing ---
- 88. ENTRANCE WOUND vsEXIT WOUND Character Entrance wound Exit wound Size Smaller than the diameter Larger edges inverted everted Abrasion collar and grease collar Present Absent Scorching, smudging and tattooing Present Absent Bleeding less more Fat extrusion less more Cherry red colour May be present absent
- 89. Yawing/ tembling • Atthe last part of the flight, • Bullet may rotate in a longitudinal axis. Base comes in front • Penetrating power is lost • Irregular lacerated wound is caused
- 90. • Entrance woundinverted edge • Exit wound everted edge • shape may vary considerably
- 91. Shored exit wound •If the body is protected at the point of exit wound • Wound will be circular • With abrasion around • Bullet will be in the vicinity
- 92. Entrance wound Exitwound Size- smaller larger Edges- inverted everted Burning blackening tattooing + --- Abrasion collar and grease collar + ---- Bleeding less more Fat and other tissues – no protrusion protrusion Metal ring +++ -----
- 94.
- 95. Tissue quake • Eventhe distant organs from the track are affected
- 96. Kennedy phenomenon • Surgicallyaltered entrance or exit wound • Happened in John. F, Kennedy ‘s assasination
- 97. Billiard ball Ricocheteffect
- 98. One entrance wound+ no exit wound • Bullet in the body • Enter the bowel and gets excreted • May enter trachea and can be spitten out • May enter the stomach and vomited out • Deflected throught the same path
- 99. One entry andmultiple exit wounds • Bullets splitting into two inside the body • Tandem bullet • Bullet strikes on the bone comes out with bone fragment
- 100. Multiple entry wounds •Bullet striking and splitting before entering • Intermediate object secondary missiles+ • Tandem bullets
- 101. Multiple entrance wounds+ single exit wound • One may remain and other exit • One excreted/ coughed
- 102. Multiple entrance woundand no exit wound • Multiple pellets lodged inside
- 103. Detection of Gunshotresidues • 1. Dermal nitrate/ Paraffin test- non-specific test • Residues are removed from the suspects hand by paraffin cast or cotton swab • Diphenylamine reagent • Positive test : blue flecks ++
- 104. • 2. Harrisonand Gilroy test • Qualitative calorimetric test • Not specific • But detects antimony, barium and lead residues
- 105. • 3. Neutronactivation analysis Detection and measurement of characteristic isotopes In a nuclear reactor Antimony and copper residues from primer
- 106. • 4. Atomicabsorption spectroscopy (AAS) Or FAAS (Flameless spectrophotometry) • 5. Scanning electron microscope- energy dispersive X-ray spectrometry even minute traces can be detected • 6. Modified Greiss Test • Specific For nitrites • Alpha –naphthol to produce visual display
- 107.