Ballistics Frank & Tony

History Who were the first to use guns and/or gunpowder?

History China= 800s, used gunpowder But ancient Greek writings of 200s reference “shooting powder”

History First Gun Load gunpowder down a tube Put a projectile down tube Ignite powder with wick

History Oldest pic of around 1326 Vase-shaped barrel

Modern-day guns

Grooves and Lands put spin on bullet

Lands and Grooves create striations on bullet

No two rifled barrels, even those manufactured in succession, will have identical striation markings Slight imperfections during rifling

Caliber What is caliber?

Caliber Diameter of gun barrel between opposite Lands Recorded in hundredths of inch or millimeters Ex: .22 inch, .38 inch, 9mm NOT exact .38 Cal may have barrel range of 0.345-0.365

Bullet-Gun Connection Need bullet from crime scene and suspected gun Shoot gun to recover undamaged bullet

Bullet to Bullet to Gun Comparison

Things to compare Number of Land and Groove Markings A 5 Land/Groove bullet does not come from a 6 land gun Width of Lands and Grooves Direction of twist A right twist bullet can’t come from a left twist barrel Striation specifics

FBI General Rifling Characteristics Files

Problems Perfect Land/Groove Markings Reality:Frags, Grit, Rust

Why can’t we get striation markings from shotgun ammunition?

Shotgun Ammunition Weigh and measure diameter of shot pellets

Shot

Shotguns and Gauges What is a shotgun’s gauge?

Gauge Diameter of barrel Ex. 12 gauge=diameter of 0.730 inches

Ballistic Mechanics

Ballistic Mechanics Trigger Pulled Activates Firing Pin Hits Primer

Ballistic Mechanics 4. Gunpowder ignited 5. Gases propel bullet through barrel 6. Spent casing bashed against breechblock Striations breechblock

Ballistic Mechanics 7. Spent Cartridge removed from barrel by an Extractor 8. Spent Cartridge thrown out of gun by the Ejector Both are sources for markings!

Ammunition

- Semi-Automatic Rifle or Shotgun

Databases IBIS DRUGFIRE

Gunpowder Residue Why is it important to know the range of gun to victim?

Gunpowder Residue Suicide (-at long range?) Self-defense (-but shot close & side of head?)

Gunpowder Residue

Gunpowder Residue

Shot Distance Determinations Need victim clothing with bullet holes Need the weapon Need identical clean clothing Need to fire shots at various distances at clean clothing to reproduce markings on clothes

Shot Distance Determinations Muzzle fire burns or melts cloths Concentrated burn marks and shot residue immediately around hole Close Range, less than 6”

Shot Distance Determinations Halo of smoke-soot around hole Shot 12” away

Shot Distance Determinations Scattered specks of shot residue with less soot around hole About 18” Away

Shot Distance Determinations Weapon fired more than 3 feet from subject, no visible powder on subject Can do a ”Bullet Wipe” Around hole will be carbon, dirt, lubricant, primer residue and lead from bullet passing

Determining the presence of powder residue on clothes Greiss Test Press a treated photo paper against questioned surface with an iron Nitrate residue stuck and chemically enhanced Lead Test Spray Sodium Rhodizonate and then acids Residue develops blue-violet color

Determining the presence of powder residue on hands Old School: Nitrate Test on hands Wax hands, lift wax Stain wax with diphenylalanine Get blue color Problem with false positives!

Determining the presence of powder residue on hands Detect: lead styphnate barium nitrate Antimony sulfide Swab hands to collect residue

Determining the presence of powder residue on hands Atomic Detection Devices Neutron Activation Analysis Atomic Spectrophotometry VERY Expensive technology!

Determining the presence of powder residue on hands Collect samples from hands for Scanning Electron Microscopy Problem with hours to scan for particles

Determining the presence of powder residue on hands Overall Problem?

Determining the presence of powder residue on hands Intentional and Unintentional washing off of residue Have a 2hr window to get accurate results.

Serial Numbers Functions and Problems?

Serial Numbers Stamped into metal History of individual gun ID Owner Track crimes committed Can file down number!

Serial Number Restoration Stamped metal area weaken When acid is applied to filed area, the strained area will burn at a faster rate than surrounding metal

Firearm Collection NEVER PUT A PENCIL DOWN BARREL AREA! WHY?

Don’t want to disturb powder Don’t want to disturb rust and dirt Will destroy or alter future striation marks Unload gun and handle by trigger guard and grip area

Ammo Collection Protect striations Bullets in wall may become more damaged if removed improperly. Wrap in paper Put into pill box

Bullet Trajectory Analysis

Bullet Trajectory Analysis

Bullet Trajectory Analysis