3Firearms: DC Sniper case Discussion What Forensic evidence can be obtained from firearms?October 2-October14 acts of violence10 killed3 injured1 assault on a Michaels craft store window
4Firearms: DC Sniper case Forensic evidence obtainedOctober 2-October 2214 acts of violenceDNA, (Multiple Sources)CasingsProjectile FragmentsProjectilesLater used to confirmsemiautomatic .223-caliber firearm
5Firearms: DC Sniper case John Allen Muhammad, 41Born John Allen WilliamsFound guilty,received the death penaltyhis execution by lethal injection on November 10, 2009.John Lee Malco, 17Life without parole
6Firearms: DC Sniper case John Allen Muhammad, 41Mildred Muhammad, the sniper's second ex-wife and the mother of three of his children, told CNN on Monday that she last saw him in 2001 at a custody hearing and had not sought to visit him in prison."I had emotionally detached from John when I asked him for a divorce," she told CNN. "And my emotions were severed when he said that you have become my enemy and as my enemy, I will kill you.“She has asserted that she was her ex-husband's target, and she blamed the first Gulf War for changing his personality.
8Firearms Demo The rifle is chambered for the .577 Tyrannosaurus Rex. According to reloading data, the 13.6 pound rifleAt a velocity approaching 2600 fps for a muzzle energy of over foot-pounds. This energy is comparable to that of the US military's .50 BMG cartridge frequently used as a heavy machinegun and anti-material rifle.
9Gun Safety Rules ALWAYS keep the gun pointed in a safe direction. ALWAYS keep your finger off the trigger until ready to shoot.ALWAYS keep the gun unloaded until ready to use.
11Firearms Chapter 15 Outline What is Firearm Identification? Three basic Rules of Firerarm SafetyWhat is BallisticsBullet Comparisons,TypesCaliberAnatomy of a bulletCartridge CasesFirearmsAnatomyAutomated Firearms Search SystemNational Integrated Ballistic Information Network (NIBIN)Gunpowder residuePrimer residueSerial Number Restoration
12What is Ballistics? Ballistics: is the study of bullets and firearms Firearm: a weapon capable of firing a projectile.
13What evidence does Firearms Identification provide? .
14What evidence does Firearms Identification provide? Comparison of bulletsIdentification of varying weapon typesRestoration of obliterated serial numbersDetection and characterization of gunpowder residues (garments and wounds)Estimation of muzzle to target distance and angle from targetPowder residues of hands
26Types of Bullets Frangible Bullets Non-Expanding Bullets -Full Metal JacketExpanding Bullets
27FrangiblesFrangible bullets break up into very small pieces upon impact with the target or the background. The penetration of this type of bullet is limited and the inflicted damage is typically near the surface of the target. They are the safest type of bullet to use in semi-populated areas, as the risk of ricochet is minimized.
28Non-Expanding Bullets Non-expanding (FMJ) bullets typically retain their general shape as the bullet penetrates and passes through target.The penetration of this type of bullet is usually much greater than frangible or expanding bullets because the frontal area of a non-expanding bullet does not increase as it penetrates.Since the wound channel is typically much narrower than that of an expanding bullet, the damage caused by a non-expanding bullet is usually much less, and quick kills on deer size game are rare.For this reason non-expanding FMJ bullets are illegal for big game hunting almost everywhere in North America.In round nose form they are favored by some African hunters for use on the largest and toughest game, principally on elephant and rhino, where very deep penetration against heavy hide and bone is required.
29Full metal jacket (or FMJ) is a bullet consistingsoft core (usually made of lead)encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy.This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead.(A bullet that is completely enclosed by the shell is termed a total metal jacket round.)The jacket allows for higher muzzle velocities than bare lead without depositing significant amounts of metal in the bore.It also prevents damage to bores from steel or armor-piercing core materials.
30Expanding BulletsExpanding or "controlled expansion" bullets are designed to deform or "mushroom" as the bullet penetrates and passes through the target.Expanding bullets are the most complex and difficult type of bullet to design, and also the most useful and numerous type of bullet.Almost all big game hunting bullets are of the expanding type. The penetration of an expanding bullet may be measured in inches or feet, depending (among other things) on the bullet's design, the bullet's sectional density, the expansion medium the bullet hits, and how fast it is traveling when it hits the expansion medium.Expanding bullets are normally used to humanely kill animals greater than approximately 30 pounds in weight by creating significant tissue damage as the bullet passes through the animal. Expanding bullets are generally constructed to (ideally) mushroom to approximately twice their initial diameter as the bullet passes through soft to firm tissue, such as skin, fat, muscle, small bones, and internal organs. The objective is to cause catastrophic damage to vital organs, especially the heart and lungs, so that the animal dies as quickly as possible.
32Understanding Caliber Caliber is simply a unit of measurement of the diameter of the bullet using inches. .45 caliber means .45 inches wide. On the other hand, mm is the metric system measurement. 9mm means 9 millimeters wide. To convert use 1 inch = 25mm.".38 special" measure " and a 9mm measures .355" instead of .354".
41ShotgunsGauge One of the earliest ways to designate the size of the bore of a gun was to figure how many bullets for it could be made from a pound of lead. Since at that time all bullets were roundballs of lead, this made a good standard.In time this designation of 'balls to the pound' became synonymous with gauge, so that what our forefathers called '28 to the pound', we now call '28 gauge'.The British commonly used the term 'bore' for 'gauge', so their '28 bore' is the same as '28 gauge' or '28 balls to the pound'. Knowing that there are 7000 grains in a pound, we can simply divide 7000 by 28 and see that 28 gauge balls weigh 250 grains each.If we measure one of those balls, we see that it is .550 inches in diameter. In modern usage that is the same as '.55 caliber'. The same relationship holds true for any size bore, of course.
47Rifling Terminology: Bore: the interior of the firearm barrel Barrel drilling leaves behind irregular marksRifling: spiral grooves that are formed in the boring of a barrel, designed to produce projectile spinProducesgrooveslands
49Lands and Grooves Firing Pin Ejector Markings on CasingLands and GroovesFiring PinEjector
50Firearm Identification Bullet Comparisons Lands - In a rifled barrel, the raised spiral ribs left between the grooves in the bore. This is the part of the barrel that actually engraves the bullet, imparts the spin to the bullet, and ultimately stabilizes the bullet.Rate Of Twist - In a barrel, the length over which the rifling grooves make one complete twist ( i.e. the length of the bore used to turn the bullet one full revolution ) e.g. 1:10 or one revolution in 10 inches. Differs from caliber to caliber.Bullet weight must be appropriate to the rate of twist or bullets will not stabilize in flight. The heavier the bullet, thus the longer, the faster the twist rate must be.
52Firearms Identification, Comparison of bullets Inner striations of gun barrel leave impressions on bulletThese striations are individual characteristicsThe widths of the lands and grooves on a bullet provide a further class characteristic that can be used as a preliminary means to determine if the submitted bullet could have been fired from the submitted firearm.
54Firearms Identification, Comparison of bullets There are three basic machining processesRifling can be cut into the inner surface of a barrel using a broach,the rifling can be formed using a hardened steel button,the rifling will be formed through a process called hammer forging. A newer method of rifling barrels, called Electrochemical Rifling, does not involve the normal machining processes of the other techniques.
55Firearm Identification Bullet Comparisons Rifling will ensure that the bullet flies true with a point-first attitude.. Methods of manufacturing areButton rifling,Cut riflingHammer forging.
56Firearm identification The first step in a firearm identification is to look at what are called class characteristics. These are characteristics common to a particular group or family of items.In the case of a firearm these would be thecaliberThe caliber of the firearms refers to the size of the bullet that is fired.Obviously a bullet that is 0.30" in diameter could not be discharged from a firearm that has an inside barrel diameter of 0.15".The rifling pattern onrifling pattern of the barrel.the inside of a barrel is often unique to a specific firearm manufacturer. This pattern is the spiral staircase pattern that can be seen when looking down the barrel of a firearm.
57Bullet ComparisonWater Tank Comparison Microscope
58Bullet Trajectory Using Hole A Mr. Vickers was found dead on the floor of his apartment. It was determined that he was shot on the floor after a struggle from eight feet away. What was the arm height of the assailant.