BALLISTICS AND FIREARMS MCCONNELL

FIREARMS IDENTIFICATION DISCIPLINE MAINLY CONCERNED WITH DETERMINING WHETHER A BULLET OR CARTRIDGE WAS FIRED BY A PARTICULAR WEAPON INCLUDES: BULLET COMPARISON WEAPON OPERATION SERIAL NUMBER RESTORATION GUNPOWDER DETECTION & CHARACTERIZATION ESTIMATING MUZZLE/TARGET DISTANCE

HOW BULLET STRIATIONS FORM:

HOW BULLET STRIATIONS FORM: HOLLOW OUT PIECE OF STEEL TO FORM BARREL LEAVING BEHIND MICROSCOPIC DRILL MARKS ON INSIDE OF BARREL OR BORE. THESE MARKS ARE AS UNIQUE TO THAT GUN AS FINGERPRINTS ARE TO A HUMAN

HOW BULLET STRATIONS FORM: THE BARREL IS THEN RIFLED RIFLING: THE IMPRESSING OR CUTTING OF GROOVES ON THE INNER SURFACE OF A BORE THESE GROOVES GUIDE THE BULLET THROUGH THE BARREL CAUSING A SPIRAL/SPINNING MOTION TO KEEP THE BULLET FROM TUMBLING TUMBLING: THE ROLLING OR TURNING END OVER END MOVEMENT CALIBER: THE MEASURED DIAMETER OF A BORE

METHODS OF RIFLING ROTATING STEEL HOOK CUTTERS BROACH CUTTER BUTTON PROCESS MANDREL RIFLING HAMMER FORGING

RIFLING LANDMARKS LANDS GROOVES THE RAISED PORTION OF THE SPIRAL CUTS MADE BY RIFLING GROOVES THE VALLEYS OF THE SPIRAL CUTS MADE BY RIFLING

THE CHARACTERISTICS OF BULLETS CLASS CHARACTERISTICS: ONCE A MANUFACTURER CHOOSES A METHOD TO MAKE A GUN THEY STICK WITH IT. EX. 5 LANDS, 5 GROOVES, LEFT INDIVIDUAL CHARACTERISTICS: THE UNIQUE STRIATIONS ON THE BORE FROM THE DRILLING PROCESS

HOW DO YOU COMPARE BULLET MARKINGS? HAS TO BE DONE WITH BULLETS FIRED INTO WATER OR SOFT COTTON FIRST ELIMINATE ALL POSSIBILITIES USING CLASS CHARACTERISTICS WHICH IS DONE BY COUNTING THE NUMBER OF LANDS AND GROOVES AND THE DIRECTION OF THE SPIRAL

HOW DO YOU COMPARE BULLET MARKINGS? THEN USE A COMPARISON MICROSCOPE TO EXAMINE THE STRIATIONS FOR INDIVIDUAL CHARACTERISTICS. TURN EACH BULLET SIMULTANEOUSLY UNTIL YOU FIND AN IDENTICAL WELL DEFINED LAND OR GROOVE. THEN TURN THE BULLETS UNTILYOU FIND AREAS OF MATCHING STRIATIONS. ROTATE TO VIEW ALL IDENTICAL AREAS.

PROBLEMS WITH BULLET IDENTIFICATION: BULLETS ARE OFTEN DAMAGED OR ALTERED TO THE POINT THAT FINDING A COMPLETE PERFECT MATCH IS VERY DIFFICULT. STRIATION MARKINGS CAN CHANGE IN A GUN OVER TIME FROM WEAR AND TEAR NO RULE FOR NUMBER OF POINTS OF COMPARISON

PROBLEMS WITH BULLET IDENTIFICATION OFTEN HAVE A BULLET WITH NO WEAPON. BUT CAN BE SOLVED IF THE WEAPON IS VERY DISTINCTIVE. SHOTGUNS HAVE SMOOTH BARRELS WHICH LEAVE NO CHARACTERISTIC MARKINGS.

GENERAL RIFLING CHARACTERISTIC FILE RUN BY THE FBI CONTAINS A LIST OF CLASS CHARACTERISTICS FOR ALL KNOWN WEAPONS PERIODICALLY UPDATED AND SENT TO ALL LOCAL LAW ENFORCEMENT GROUPS

PARTS OF A GUN ***GO OVER HANDOUT CARTRIDGE CASES: THE CASE OR SHELL THAT SURROUNDS THE BULLET BREECHBLOCK: THE REAR PART OF A FIREARM BARREL

ACT OF FIRING: HOW DOES A GUN WORK? PULL THE TRIGGER TO RELEASE THE WEAPON’S FIRING PIN THE PIN STRIKES THE PRIMER WHICH IGNITES THE POWDER GASSES FROM THE BURNING POWDER FORCE THE BULLET FORWARD THROUGH THE BARREL THIS SIMULTANEOUSLY PUSHES SPENT CARTRIDGES BACKWARD AGAINST THE BREECHBLOCK

MARKS ON CARTRIDGE CASES (WHAT CAN WE SEE?) SHAPE OF FIRING PIN IMPRESSED INTO THE METAL OF THE PRIMER BACKWARDS MOVEMENT IMPRESSES CARTRIDGE WITH SURFACE MARKINGS OF THE BREECHBLOCK MARKS FROM THE EXTRACTOR MECHANISM THAT WITHDRAWS CARTRIDGE FROM CHAMBER

MARKS ON CARTRIDGE CASES (WHAT CAN WE SEE?) MARKS FROM THE EJECTOR MECHANISM THAT THROWS CARTRIDGE FROM THE FIREARM MARKS ALSO FORM ON SHOTGUN SHELLS BUT THEY ARE UNLIKE BULLET MARKS

AUTOMATED FIREARMS SEARCH SYSTEMS DRUGFIRE EARLY SYSTEM DEVELOPED FOR FBI EMPHASIZED MARKINGS ON CARTRIDGE CASINGS & SOME BULLET STRIATIONS LOOKED AT IMAGES THROUGH A MICROSCOPE ATTACTED TO A VIDEO CAMERA

AUTOMATED FIREARMS SEARCH SYSTEMS INTEGRATED BALLISTIC IDENTIFICATION SYSTEM (IBIS) SYSTEM DEVELOPED FOR THE ATF FOCUSED ON FEATURES FROM EXPENDED BULLETS AND CARTRIDGE CASINGS USED PICTURES FROM DIGITAL MICROSCOPES

AUTOMATED FIREARMS SEARCH SYSTEMS NATIONAL INTEGRATED BALLISTICS INFORMATION NETWORK (NIBIN, 1999) COMBINE DRUGFIRE AND IBIS TO FORM A COOPERATIVE SYSTEM DIVIDED SYSTEM JOBS INTO TWO CATEGORIES COMMUNICATIONS – FBI SYSTEM SITES - ATF

BALLISTIC FINGERPRINTING GOAL OF NIBIN A SYSTEM THAT WOULD CAPTURE AND STORE MARKINGS ON BULLETS AND CARTRIDGES TEST FIRED FROM ALL HANDGUNS AND RIFLES BEFORE THEY ARE SOLD GOAL HASN’T BEEN REACHED YET

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? GUNPOWDER RESIDUE PARTIALLY BURNED AND UNBURNED PARTICLES OF GUNPOWDER DISCHARGED WHEN A WEAPON IS FIRED DISTANCE DETERMINATION CALCULATING DISTANCE BETWEEN FIREARM AND A TARGET BASED ON THE DISTRIBUTION OF POWDER PATTERNS OR THE SPREAD OF A SHOT PATTERN

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? HANDGUNS AND RIFLES IF YOU HAVE A WEAPON COMPARE POWDER RESIDUE PATTERN ON VICTIM’S CLOTHING OR SKIN TO PATTERNS FOUND WHEN FIRING SUSPECT’S WEAPON FROM VARYING DISTANCES AT A TARGET USING THE SAME AMMUNITION

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? HANDGUNS AND RIFLES IF YOU DON’T HAVE A WEAPON SEARCH FOR RECOGNIZABLE CHARACTERISTICS AROUND THE BULLET HOLE

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? CHARACTERISTICS IF GUN WAS TOUCHING OR LESS THAN AN INCH FROM THE TARGET THEN YOU WILL SEE: A HEAVY CONCENTRATION OF SMOKELIKE VAPOROUS LEAD SURROUNDING THE HOLE SCORCH MARKS OR MELTING AROUND THE HOLE

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? CHARACTERISTICS IF GUN WAS TOUCHING OR LESS THAN AN INCH FROM THE TARGET THEN YOU WILL SEE: STELLATE/STAR-SHAPED TEAR PATTERNS AROUND THE HOLE WHICH ARE FORMED BY BLOW BACK OF MUZZLE GASES

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? CHARACTERISTICS IF GUN WAS GREATER THAN 3 FEET FROM THE TARGET THEN YOU WILL SEE: NO POWDER RESIDUE AT ALL BULLET WIPE: DARK RING AROUND THE PERIMETER OF THE ENTRANCE OF A BULLET HOLE MADE OF CARBON, DIRT, LUBRICANT, PRIMER RESIDUE, AND LEAD

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? CHARACTERISTICS IF GUN WAS 12-18 INCHES FROM THE TARGET THEN YOU WILL SEE: A HALO OF VAPOROUS LEAD IF GUN WAS UP TO 25 INCHES FROM THE TARGET THEN YOU WILL SEE: SPECKS OF UNBURNED OR PARTIALLY BURNED POWDER

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? WHEN THE WEAPON IS A SHOTGUN IF YOU HAVE A WEAPON THEN DISTANCE IS DETERMINED BY FIRING THE SUSPECT WEAPON FROM VARYING DISTANCES USING THE SAME TYPE OF AMMUNITION LOOK FOR SIMILARITIES IN THE SHOT PATTERNS

HOW CAN YOU TELL HOW FAR AWAY THE GUN WAS? IF YOU DON’T HAVE A WEAPON FIRED FROM UP TO 4-5 FEET FROM THE TARGET, THE SHOT ENTERS AS A CONCENTRATED MASS WITH A HOLE LARGER THAN THE BORE USUALLY THE SHOT SPREAD INCREASES 1 INCH FOR EACH YARD OF DISTANCE CHOKE: INTERIOR CONSTRICTION PLACED NEAR THE MUZZLE OF A SHOTGUN BARRELL TO CONTROL SHOT DISPERSION, GREATER CHOKE EQUALS LESS SPREAD

HOW DO I LOCATE POWDER RESIDUE ON GARMENTS? VISUAL EXAMINATION – CAN I SEE IT WITH MY NAKED EYES? INFARED EXAMINATION – CAN I SEE IT WITH AN INFARED CAMERA/TOOL? CHEMICAL EXAMINATION – DO CHEMICAL TESTS PICK UP ANY TRACES OF POWDER?

HOW DO I LOCATE POWDER RESIDUE ON GARMENTS? GREISS TEST CHEMICAL TEST USED TO DEVELOP PATTERNS OF GUNPOWDER RESIDUE AROUND BULLET HOLES BY DETECTING THE PRESENCE OF NITRATES

PRIMER RESIDUE THE UNUSED PORTION OF PROPELLANT DURING A GUNSHOT CAN BE DETECTED IN SEVERAL WAYS USED TO FOCUS ON NITRATES BUT NOW FOCUSES ON BARIUM AND ANTIMONY

DETECTING PRIMER RESIDUE DERMAL NITRATE TEST – EARLY TEST, PAINTED SUSPECT’S HAND WITH HOT WAX, LET IT DRY, TEST IT WITH DIPHENYLAMINE, BLUE MEANS POSITIVE, BUT GAVE MANY FALSE POSITIVES FOR THINGS LIKE FERTILIZER ADHESIVE – USES TAPE OR ADHESIVES TO REMOVE ANY PARTICLES OF PRIMER RESIDUE FROM SUSPECT’S HAND WHICH ARE THEN TESTED IN A LAB.

DETECTING PRIMER RESIDUE SWABBING – SWAB BOTH HANDS OF SUSPECT WITH 5% NITRIC ACID SOLUTION, PROBLEM IS RESIDUE COMES OFF EASILY AND SO MIGHT HAVE RUBBED OFF ALREADY SEM TESTING – USES MICROSCOPE CONNECTED TO AN X-RAY ANALYZER TO LOOK FOR DISTINCTIVE PARTICLES, VERY TIME CONSUMING AND EXPENSIVE

DETECTING PRIMER RESIDUE NEUTRON ACTIVATION ANALYSIS – USES A NEUTRON SOURCE TO LOCATE AND IDENTIFY THE ELEMENTS IN PRIMER RESIDUE, VERY EXPENSIVE, LIMITED, AND STRICTLY CONTROLLED BY THE GOVERNMENT FLAMELESS ATOMIC ABSORPTION SPECTROPHOTOMETRY – TEST BASED ON HOW DIFFERENT COMPOUNDS ABSORB LIGHT

SERIAL NUMBER RESTORATION WHEN THE SERIAL NUMBER OF A GUN HAS BEEN FILED OFF SERIAL NUMBERS ARE STAMPED INTO THE METAL BODY OR FRAME CAN RESTORE BY CLEANING, POLISHING AND THEN APPLYING AN ETCHING AGENT

HOW TO COLLECT FIREARM EVIDENCE: HOLD FIREARM BY TRIGGER GUARD OR GRIP MAKE SURE WEAPON IS UNLOADED WITH POSITION AND AMMO RECORDED MARK CHAMBER POSITION WHERE IT LINES UP WITH BARREL PLACE EACH ROUND/MAGAZINE IN SEPARATE CONTAINER AFTER CHECKING FOR FINGERPRINTS

HOW TO COLLECT FIREARM EVIDENCE: COMPLETE AN EVIDENCE TAG SERIAL NUMBER MAKE MODEL INVESTIGATOR’S INITIALS FOLLOW CHAIN OF CUSTODY

HOW TO COLLECT AMMUNITION EVIDENCE: PROTECT ALL CLASS AND INDIVIDUAL CHARACTERISTICS SCRIBE BULLETS, CASING AND SHELLS WITH INVESTIGATOR’S INITIALS AT EITHER THE BASE OR NOSE WRAP BULLET IN TISSUE PAPER BEFORE PACKAGING IT FOR THE CRIME LAB

HOW TO COLLECT AMMUNITION EVIDENCE: LEAVE ALL TRACE MATERIALS ON BULLET NOTE EXACT LOCATION WHERE ALL CASINGS WERE FOUND

HOW TO COLLECT GUNPOWDER EVIDENCE: PRESERVE ALL CLOTHING PLACE IN SEPARATE PAPER BAGS AVOID CUTTING OR TEARING AROUND THE HOLE AIR DRY WET CLOTHES OUT OF SUNLIGHT

TOOLMARKS ANY IMPRESSION, CUT, GOUGE OR ABRASION CAUSED BY A TOOL COMING INTO CONTACT WITH ANOTHER OBJECT

COMPARING TOOL MARKS USUALLY PROVIDES GOOD CLASS CHARACTERISTICS BUT SELDOM GIVES INDIVIDUAL CHARACTERISTICS CLASS: TYPE OF TOOL, MAKE, MODEL INDIVIDUAL: DAMAGE ON TOOL