Lec Flashcards
The identification of fired bullets, cartridge cases or other ammunition components as having been fired from a specific firearm.
FIREARMS IDENTIFICATION
Forensic Ballistics is sometimes properly called
FIREARMS IDENTIFICATION
PRINCIPLES OF IDENTIFICATION THROUGH BULLETS
a. No two barrels and microscopically identical as the surface of their bores all possess individual characteristics markings.
b. When a bullet is fired from a rifled barrel, it becomes engraved by the riflings and this engraving on a bullet fired from one barrel will be different from that on a similar bullet fired from another barrel. And conversely, the engraving on bullet from the same barrel will be the same.
c. Every barrel leaves its “thumbmark” on every bullet which is fired through it, just as every breech face leaves its “thumbmark” on the base of the fired
cartridge case.
PRINCIPLES INVOLVE IN SHELL IDENTIFICATION
- The breech face and firing pin of every single firearm have individual microscopic individuals of their own;
- Every firearm leaves its fingerprint or thumbprint on every cartridge it fires;
- That, since the breech face of every weapon has individual distinction, the imprints of all cartridge cases fired from the same weapon are the same
PRINCIPLES OF IDENTIFICATION THROUGH CARTRIDGE CASE/SHELLS
a. The breech face and striker of every single firearm leave a microscopically individualities of their own
b. The firearm leaves its “fingerprints” or “thumbmark” on every cartridge case which it fires.
c. The whole principles of identification is based on the fact that since the breech face of every weapon must be individually distinct, the cartridge cases which is fired are imprinted with this individuality. The imprint on all cartridge cases fired from the same weapon are always the same, those on cartridge cases fired from different weapons must always be different.
- These were set even before the manufacture of FAs. These are factory specifications.
CLASS CHARACTERISTIC
- Are determined after the manufacture of FA. Such marks
are so minute that the use of the lens with high magnification is necessary to discover individuality.
INDIVIDUAL CHARACTERISTICS
CLASS CHARACTERISTICS
● BORE DIAMETER
● NUMBER OF LANDS AND GROOVES
● WIDTH OF THE LANDS
● WIDTH OF THE GROOVES
● DIRECTION OF TWIST
● PITCH OF RIFLING
● DEPTH OF THE GROOVES
- marks left on a fired bullet caused by its contact to the ‘elevated portion(lands) of the bore of the firearm.
LAND MARKS
It appears as slight depressions or scratches the cylindrical surface of the fired bullet.
LAND MARKS
marks found on a fired bullet caused by the grooves of the barrel which is the same number as that of the landmarks.
GROOVE MARKS
Marks that are generally found on fired revolver.
SKID MARKS
It is more or less located at the anterior porti bullet due to its forward movement from the chamber the gun before it initially rotates.
SKID MARKS
- marks found on those bullet fired from a “loose-fit” barrel wherein the rifling are already been badly worn-out.
STRIPPING MARKS
Worn-out in the rifling of the firearms can be cause by either chemical reaction brought about by rust(corrosion) or through excessive use (erosion)
STRIPPING MARKS
- marks commonly, found on bullet fired from a revolver cause by its forward movement to the barrel that is poorly aligned to the cylinder
SHAVING MARKS
marks found on fired bullets passing through either on oily or oversize barrel
SLIPPAGE MARKS
- mark generally found at the base portion of the cartridge case more specifically near center of the primer cup in a center fire cartridge or at the rim cavity of a rimfire cartridge.
FIRING PIN MARK
Considered as one of the most important marks for identification of firearms using fired shell.
FIRING PIN MARK
- mark found at the base portion of the shell cause by backward movement to the breech face of the block of the firearm.
BREECH FACE MARK
sometimes called”Secondary Firing Pin mark” found in the primer near the firing pin mark.
SHEARING MARK
- marking found at the two sides of the rim cause by the magazine lips during the loading of the cartridge into the magazine for firing.
MAGAZINE LIP MARK
- mark mostly found around the body of the fired cartridge case cause by the irregularities of nips inside the walls of the chamber .
CHAMBER MARK
mark mostly found at the extracting groove of the fired cartridge case.
EXTRACTOR MARK
Cause by its withdrawal from the chamber.
Extractor mark
mark generally found on cartridge case fired from an automatic firearms.
EJECTOR MARK
It is located near the rim of the case cause by the throwing of shell from the firearm to the area of shooting.
Ejector mark
- test performed to extract the nitrates embedded in the skin.
PARAFFIN TEST
- a test that determines the presence and location of
nitrate, chemical needed is diphenylamine reagent.
DIPHENYLAMINE TEST OR DPA TEST
half of evidence & test bullet is projected:
INTERMARRIAGE
- the critical side by side examination of evidence and test bullet/shell.
JUXTAPOSITION
means putting two things together to emphasize their contrast between them.
Juxtapose
Used for determining weights of bullets and shotgun pellets for possible
ANALYTICAL OR TORSION BALANCE
Determination of type, and make of firearm from which it was fired
ANALYTICAL OR TORSION BALANCE
Measurements are expressed in Grains or Grams.
ANALYTICAL OR TORSION BALANCE
- Consist of a wooden box, 12“x”12”x 96, with a hinged to cover and with one end open.
BULLET RECOVERY BOX
This long box is filled with ordinary cotton and separated into sections by cardboard petitions.
BULLET RECOVERY BOX
- An instrument very much similar with the bullet
comparison microscope,where 2 fired bullets or shells can be compared in one setting of the firearms examiner .
CP-6 COMPARISON PROJECTOR
Inventor of CP-6 COMPARISON PROJECTOR.
William Howard Livens, engineer and British Army, was the
inventor .
- Type of instrument used in measuring pitch of rifling firearms.
HELIXOMETER
- A machine use for testing the accuracy of a firearm.
MACHINE REST
- an instrument used for making measurements such as bullet diameter and bore diameter .
CALIPER
- a small instrument sometimes used in examining the internal surface of the gun barrel in determining the irregularities inside the bore of the gun barrel.
ONOSCOPE
- Equipment used in firearms identification. It contains a series of microscopic lenses of different magnification that can be used in examining fired bullet or fired shells to determine their class characteristics and also for orientation purposes
SHADOW GRAPH
- unlike the bullet comparison microscope does not have
any camera attachment and no photomicrograph can be taken for court presentation.
STEREOSCOPIC MICROSCOPE
It is generally used in the preliminary examination of fired bullets and fired shells to determine the relative distribution of the class characteristics or for so-called orientation purposes.
STEREOSCOPIC MICROSCOPE
invented the first Stereoscopic-Style Microscope with
two eyepieces in 1671.
Cherubin d’Oreans (1671)-
- designed the first successful stereomicroscope.
Francis Herbert Wenham (19”) of London
- It is used primarily for determining bore diameter of firearms.
TAPER GAUGE
This instrument is very useful for giving quick idea as to the caliber of a gun.
TAPER GAUGE
measure the velocity of bullet.
CHRONOGRAPH
Inventor of CHRONOGRAPH
Alfred Lee Loomis (1918)- inventor
-similar in use with Caliper .
MICROMETER (C-CLAMP LIKE)
Inventor of MICROMETER (C-CLAMP LIKE)
William Gascoine (17)- first ever inventor .
- a pointed instrument used to mark:
STYLUS
- a mechanical trigger pull trigger tester
TRIGGER PULL GAUGE
- used to handle bullets
TWEEZERS
This valuable instrument is especially designed to permit the firearms examiner to determine similarity and dissimilarity between two fired ballets or two fired cartridge
cases by simultaneously observing their magnified image.
COMPARISON MICROSCOPE
It is actually two microscope couple together with a single or two eyepiece, so that when one comparison eyepiece
he through this seeing one half of what is under the other - in other words, half of the evidence bullet and half of the test bullet.
COMPARISON MICROSCOPE
This is generally in the preliminary examination of fired bullets and fired shells.
STEREOSCOPE MICROSCOPE
To determine the location of the extractor márks and ejector marks for orientation purposes.
STEREOSCOPE MICROSCOPE
It can be used also in the close-up examination of tampered serial numbers of firearms.
STEREOSCOPE MICROSCOPE
This is similar to the comparison microscope.
COMPARISON PROJECTOR - CP6
Two fired bullets or two fired shells can be compared in one setting of the firearm examiners.
COMPARISON PROJECTOR - CP6
A magnified image appears on a large screen and can be observed in a comfortable viewing distance.
COMPARISON PROJECTOR - CP6
No mental strain because comparison of evidence is faster, easier and less tiresome, thus allowing a more efficient
and productive use of investigative time in the Criminal Laboratory.
COMPARISON PROJECTOR - CP6
For obtaining best fired bullets or test fired cartridge cases from the suspected firearms submitted to the ballistic laboratory in test firing suspected firearms, it is standard
procedure to use ammunitions that are of the same caliber, make or brand and manufactured in the same year with that of the evidence bullet or shell.
BULLET RECOVERY BOX
Water is one of the means to obtain test bullets and test shells because the microscopemarks on the cylindrical or peripheral surface of the bullets are preserved for
good use. The same is true with cotton.
BULLET RECOVERY BOX
This projector determines the width and lands width of grooves, diameter ánd twist of a fired bullet.
MEASURING PROJECTOR-MP6
This instrument determines the bullet diameter and barrel length
VERNIER CALIPERS
used to measure external diameter or width of an object
Outside jaws
used to measure internal diameter of an object
Inside jaws
used to measure depths of field through object or a hole
Depth gauge
used to block movable part to allow the easy transferring of a measurement.
Retainer
This more or less determines the weights of the bullets, shots and pellets for possible type, caliber and firearm from which they were fired.
ANALYTICAL BALANCE
Use for determining the bore diameter of the firearm.
TAPER gauge
For examining the interior surface of the gun barrel.
ONOSCOPE
For measuring the pitch of rifling. Pitch of Rifling- is the distance advanced by the rifling in one complete turn or the distance travelled by the bullet in one complete turn.
HELIXOMER
For determining the speed of the bullet or the muzzle velocity of the bullet.
CHRONOGRAPH
is any substance that may cause an explosion by its sudden decomposition or combustion.
Explosive
a material either pure single substance or mixture of
substances which is capable of producing an explosion by its own energy.
Explosive
Are combustible materials containing within
themselves all oxygen needed for their combustion that burn but do not explode and function by producing gas that produces explosion.
PROPELLANT OR LOW EXPLOSIVES
Example of PROPELLANT OR LOW EXPLOSIVES
Black powder, smokeless powder, firecrackers, and pyrotechnics
- Explode or donate when they are heated or
subjected to shock.
PRIMARY EXPLOSIVE OR INITIATORS
They do not burn. Sometimes they do not even contain the elements necessary for combustion.
PRIMARY EXPLOSIVE OR INITIATORS
The materials themselves explode and the explosion results whether they are confined or not.
PRIMARY EXPLOSIVE OR INITIATORS
PRIMARY EXPLOSIVE OR INITIATORS Example
Mercury fulminate, lead azide
- Explode under the influence of the shock of the explosion of primary explosive.
HIGH EXPLOSIVES
They do not function by burning, in fact not all of them can be ignited by a flame and in small amount generally burn tranquilly and can be extinguished easily.
HIGH EXPLOSIVES
If heated to a high temperature by external heat or by their own combustion, they sometimes explode.
HIGH EXPLOSIVES
Example of HIGH EXPLOSIVES
Ammonium nitrate, TNT ,dynamite, nitroglycerine,
picric acid, plastic explosives.
-rapid combustion, decomposition of gases, & consequent violent increase of pressure, usually causes a loud report.
EXPLOSION
Sudden breaking apart,shattering or bursting in
pieces by internal pressure, as that of gas or steam(pressure explosion).
EXPLOSION
- One resulting from practically instantaneous decomposition or combustion of unstable compounds such as nitroglycerine, TNT or mercury fulminate, as distinguished from explosions of black powder.
DETONATION
- Any substance that may cause explosion by its sudden decomposition or combustion.
EXPLOSIVE
- hollow projectile of iron generally spherical, containing explosive material which is fired by concussion or by time fuse.
BOMB
LOW EXPLOSIVES VS HIGH EXPLOSIVES
Due to difference in explosion velocities between low & high explosives,difference in their effects are rather obvious -low explosives produce dull ‘boom’ & generally, ‘push’ type of damage, while high explosives detonate w/ sharp ‘crack’ & produce violent shattering type of damage localized at the site of the explosive, w/ intensely of disruptive or shattering damage diminishing rapidly w/distance from this point. Ex. TNT, dynamite, nitroglycerine, picric acid.
- cheapest and most readily available salt of nitric acid.
Ammonium nitrate
- most widely used explosive in the Philippines.
TNT (trinitrotoluene)
- most widely used commercial explosive.
Nitroglycerine
considered as one of most important military
explosive used today.
RDX (Royal Demolition Explosive)
- plastic explosive which is white and dough like in texture.
C4
is principal component in filler used in tear gas solutions
Chloroacetophenone-CN
- Molotov cocktail which is incendiary device, acids mixed with gasoline, alcohol and gasoline, etc.
Fire Bombs
pressure inside container exceeds its structural strength
MECHANICAL EXPLOSION A.k.a. Hydraulic Explosion
Example of MECHANICAL EXPLOSION A.k.a. Hydraulic Explosion
Air pressure tanks for cleaning or paint spray, Water pressure tank, Air pumped kerosene burner
Electricity arcs through air, 2 objects of different electrical potential:brought close to one another, Large amount of heat develops, Heat rapidly expands air in and around arc producing popping sound of arc.
ELECTRICAL EXPLOSION
Release of significant amount of energy by fusion or fission
NUCLEAR EXPLOSION
Result: significant increase of destructiveness
NUCLEAR EXPLOSION
Example of NUCLEAR EXPLOSION
Atomic Explosion
Chemical reaction producing heat and gas at rate faster than surroundings can dissipate
CHEMICAL EXPLOSION
- 4 lands, 4 grooves, right hand twist and lands and grooves are of equal width. (4-R-G=L)
Steyer type
- 5 lands and grooves, right hand twist, and lands and grooves of equal width. (5-R-G=L)
Smith and Wesson type
- 6 lands and grooves, right twist, narrow lands and broad grooves. (6-R- G-2x)
Browning type
- 6 lands and grooves, left twist, narrow lands and broad groove. (6-L-G-2x)
Colt type
- 7 lands and grooves, right twist, narrow lands and broad grooves (7-R-G3X)
Webley type
- 6RG3X (six lands and grooves twist to the right, groove width is three times wider than the land)
Winchester type
- 4RG2X, which means there are 4 lands and grooves that twist to the right but the grooves are twice wider than the lands
Carbine type
- 4 lands and grooves, right twist, narrow land and broad grooves (4-R-G3X)
Army type
- are those recovered from recovery box for comparison purposes with the evidence bullet.
Test Bullets
- are those recovered from the crime scene.
Evidence bullet
- are those recovered during test firing for comparison purposes with the evidence shell
Test shells
- are those recovered from the crime scene
Evidence shell
- the firearm is fired from a bullet recovery box or water tank in order to obtain test bullets and test cartridge cases.
Test Firing
- signifies a match between two specimens
Identification
- represents a no match between the examined items of evidence
Exclusion
- indicates that the specimen submitted could neither be identified now eliminated as having been fired by a particular weapon based on the quantity and quality of microscopic markings.
No Conclusion
a. Specific for lead
b. Vaporous lead is usually found closer than arm’s length
Sodium Rhodizonate Test
Results of GSR Hand Tests:
a. Negative result is may be caused by:
i. Washing the hands.
ii. Shooter may have been wearing gloves
iii. Lead free ammunition
is no longer used and is generally
considered unreliable in GSR testing because of its no specificity. The main problem it was recently realized cosmetics and other everyday preparations as well as being present in cigarettes and cigars, so that the value of a swab as a positive indication of recent gun handling is lost.
The so-called “dermal nitrate test” or “paraffin test”
Inventor of “dermal nitrate test” or “paraffin test”
This kind of test was developed by Teodoro Gonzales of Mexico in 1933
Specific for partially burned and unburned gunpowder particles, most specifically, nitrates found in the partially burned gunpowde
Modified Griess test
○ Tests for Lead, Antimony, and Barium particles
○ Studies suggest it stays on the hands approximately for 6 hours
Examined under the Scanning Electron Microscope (SEM)
