Please enable JavaScript.
Coggle requires JavaScript to display documents.
Cartridge and Shotshell Examination
retrieved Feb 11, 2020
https…
Cartridge and Shotshell Examination
retrieved Feb 11, 2020
https://firearms-examiner.training.nij.gov/
Module 9
Identification
Evidentiary Value
- striations and impressions
- fire pin impressions
- action, extractor, ejector marks, mechanism marks
Individual Characteristics
- various parts
- can be reproducible
- striated marks/impressions
Developments
- optical systems and peripheral equipment
- digital imaging and management
- digitized ammunition reference resources
Prerequisites for Examination
- Laboratory Policies
- Documentation
- Equipment
- Class Characteristics
- Microscopic Marks
- Test Standards
-
Physical Characteristics
marks on fired cartridge cases and shotshell cases reflect both class and individual characteristics of striated and impressed toolmarks.
Individual characteristics
Marks produced by the random imperfections or irregularities of tool surfaces.
-
Subclass characteristics
Discernible surface features of an object that are more restrictive than class characteristics
Pattern Identification
process of determining whether or not the details of striated marks or impressions on two objects correspond
-
-
-
Fired Case Examination
Microscopic Procedure
- Review laboratory protocols
- Complete administrative requirements
- Follow laboratory safety protocols
- presence of trace evidence? and follow laboratory protocol for collection
- latent fingerprint examinations?
- other examinations?
Microscopic Comparisonsv
- maintenance and calibration standards met
- appropriate level of magnification
- same type and orientation of light source for each comparison microscope stage
-
-
-
-