Firearms and Toolmarks Flashcards
(17 cards)
What is firearms examination?
The forensic discipline that indentifies bullets, cartridge, cases, and other ammunition components as having been fried by a particular firearm
What is the caliber of a bullet?
The diameter of the bullet being fired
What are the different variations in bullets?
Caliber
Base construction
Base shape
Nose construction
Nose shape
Cannelures
What are grooves and lands?
On a bullet:
Grooves = outwards
Lands = inwards
Class characteristics
What are the identifying parts of a cartridge case and where are they?
(draw it)
Class:
Head stamp
Individual:
Firing pin impression & scrape mark
breechface marks
Ejector mark (on face)
Extractor mark (on side of face)
What is IBIS?
- Integrated Ballistic Identification System
- Computerized system that captures, stores, and compares digital images of ballistic evidence
What is NIBIN?
- National Integrated Ballistic Information Network
- ATF program that uses this technology in a cohesive network and law enforcement plan
What are the three chemical tests for distance determination analysis?
Modified Griess Test
for nitrite compounds
Dithioxamide Test
for copper bearing materials
Sodium Rhodizonate Test
For lead residues
What is the gun control act of 1968?
All newly-manufactured firearms
produced by licensed manufacturers in the United States
and imported into the United States must bear a serial number
What is the first thing you must know for serial number restoration? What do you do next?
Must test for metal type (magnet test)
If magnetic (ferrous, contains iron): use chemical etchants designed for steel
Not magnatic (nonferrous): use chemical ethcants designed for other metals
Chemical, steel: Fry’s, Turner’s, and Davis Reagent, Nitric Acid
Chemical, other metals: ferric chloride, acidic ferric chloride, 25% nitric acid, 10% sodium hydroxide
What is a toolmark?
Any impression, scratch, or abrasion made when contact occurs between a tool and an object
What are class and individual characteristics of tools?
Class characteristics: type, shape, size
Individual characteristics: features from wear and damage
What are common types of toolmarks?
- Abrasion marks: made when one surface slides along another (scratching)
- Cutting marks
- Indentation marks: when a tool is pressed against a softer surface, resulting in an impression of the harder tool in the softer material
What are impressions?
Marks or imprints left when an object is pressed against a surface, typically without any sliding or cutting motion
Tire tracks and shoeprints
What are the two types of shoeprint retrieval?
Dental stone casting
Mold that is poured, works on malleable surfaces such as dirt, sand, and clay
Static lifting
Uses a film to static lift dust and residue, works on hard surfaces such as wood, stone, or tile
What is the casting material used for toolmarks?
Mikrosil
A silicone-based casting material that involdes a base and catalyst mixed together
What is TreadMate?
A database containing data on more than 5,000 vehicle tires and tread patterns
