- 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
Sufficient Agreement and Best Known Nonmatch
Home > Toolmark Identification > Basic Toolmark Identification > Sufficient Agreement and Best Known Nonmatch
The second of the three principles of the AFTE Theory of Identification indicates that the degree of correspondence which must be exceeded to constitute sufficient agreement for an identification is the best known nonmatch (by each individual examiner) to have been produced by different tools. Ideally, the examiner would gain experience in this during their initial training period rather than when they begin to perform actual examinations on their own.
The third principle of the AFTE Theory of Identification indicates that, although founded on the scientific method and reproducibility of results, the interpretation is subjective in nature. It is the policy of most laboratories that a second qualified examiner verify the findings of the first examiner.
Ultimately, sufficient agreement is the product of the examiner’s personal training, skills, and experience in
- recognizing corresponding patterns of matching striations,
- recognizing corresponding patterns within impressed toolmarks,
- determining the best known non-match in their personal experience,
- comparing striated and impressed toolmarks.
It is incumbent on each examiner to rely on their training and experience to identify and to be able to articulate the process used to determine sufficient agreement and best known nonmatch.
