- 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
- Introduction
- Objectives
- AFTE Knowledge and Ability Factors
- Powders and Residues
- Examination
- Distance Determination
- Significance of Results
- Contact Shot
- Nitrite Residues
- Vaporous Lead Residues
- Residues Consistent with the Passage of a Bullet
- Residues Consistent with the Discharge of a Firearm
- Interpretation Challenges
- Reproduction of Results
- Nitrite Residue Patterns
- Shot Patterning
- Chemical Testing
- Shot Pattern Reproduction
- Selected Bibliography
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Distance Determination
Home > Gunshot Residue and Distance Determination > Distance Determination
The next step involves the interpretation of the positive results acquired during the performance of gunshot residue analyses in the previously described sequence of tests. These results are the basis for comparison with known-distance test firings of residue patterns. Positive results are duplicated to create known standards by firing the evidence firearm and ammunition at test targets under controlled conditions. Several types of detectable residues may be deposited and will vary with the distance from the target.
While gunshot residues hold significant potential for determining the facts in a shooting incident, there are also limitations. Some types of residues may be strongly indicative of or consistent with the discharge of a firearm. However, these same residues may have no value in determining the distance involved because the deposits do not constitute reproducible patterns, only random effects of firing the firearm.
The types of positive and negative data that should be noted based on the examinations include
- the Modified Griess Test results for the presence of reproducible patterns of nitrite residues, or simply scattered residues for which a maximum distance for deposition can be determined,
- the Dithiooxamide Test results for the presence of bullet wipe consistent with the passage of a copper-bearing bullet,
- the Sodium Rhodizonate Test results for the presence of particulate lead only, consistent with the discharge of a firearm; bullet wipe consistent with the passage of a lead-bearing bullet; or vaporous lead residue for which a maximum distance for deposition can be determined.
