- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Prerequisites for Examination
Home > Cartridge and Shotshell Examination > Identification > Prerequisites for Examination
Prior to conducting any examinations or microscopic comparisons of fired or unfired cartridge cases or shotshell cases, certain preliminaries should be addressed.
Laboratory Policies
Laboratory policies are followed, including
- chain of custody,
- laboratory safety,
- trace evidence,
- coordination of examination sequencing across disciplines to preclude loss of trace evidence,
- evidence marking and packaging.
Documentation
Basic descriptive information should be documented prior to any examination or comparison. A laboratory-approved worksheet may be available to allow for contemporaneous documentation.
Equipment
Stereo and comparison microscopes should be calibrated and maintained prior to examination.
Click here to read the stereo and comparison microscope calibration sections in Module 7, Equipment/Instrumentation.
Class Characteristics
Determination of class characteristics is performed according to laboratory protocol. (AFTE protocol recommendations can be requested from the AFTE website.)
Rimfire cartridge case ejector
mark comparison
Microscopic Marks
The evidence is examined to establish that it bears microscopic marks of value suitable for comparison. Although the marks are suitable for comparison, they may not be sufficient for identification. This is determined during the actual comparison.
Test Standards
Test standards (known standards) are obtained and appropriately marked and preserved. Many forensic firearms laboratories maintain a collection of known standards, referred to as the standard ammunition file (SAF). The goal of such a physical file is to determine what cartridge types and which manufacturer or marketer is represented by the evidence. The examiner should make use of the SAF in selecting and firing test standards in order to match physical characteristics and headstamps.
Examiners should always be aware that reference collections and database programs are seldom all inclusive; all available resources and examiners should be consulted.
