Dynamic Mark
Definition
A combination of compression and sliding in one contact. The most common real-world tool mark and the hardest to reproduce in test impressions.
- Field
- Tool mark examination
- Composition
- Compression plus sliding motion
- Frequency
- Most common real-world tool mark type
- Difficulty
- Hardest to reproduce in test impressions
Common questions
Why is a dynamic mark harder to compare than a static compression mark?+
The sliding component means the tool's contact angle, speed, and pressure all vary continuously across the mark, so no two dynamic marks from the same tool are ever pixel-identical, which forces examiners to rely on individual class and subclass striae patterns rather than an exact silhouette match.
How do examiners attempt to reproduce test impressions for comparison against a dynamic mark?+
Examiners try to replicate the original tool's likely angle and motion using an exemplar surface, generating multiple test marks at varying angles and pressures, then compare the resulting striae patterns to the questioned mark rather than expecting one test strike to reproduce it exactly.
Related terms
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Impression Mark
- A compression mark made when a tool meets a softer surface with no relative motion. Hammer face on brass, plier jaw crimping...
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
- Striation Mark
- A scratch pattern made when a tool slides across a softer surface. Pry bar dragging across painted wood, blade cut, a screwdriver...
- Test Mark
- A reference mark deliberately made with a suspect tool against a soft medium (lead, clay, aluminium) so it can be compared against...