Bullet Trajectory Kit (BTK)
Definition
A laser-based trajectory projection system by Sirchie that replaces the physical rod with a laser module, projecting a visible beam along the bullet's path for documentation photography.
- Manufacturer
- Sirchie
- Mechanism
- Laser module replacing trajectory rods
- Output
- Visible beam along the bullet path
- Use
- Scene documentation photography
- Field
- Bullet trajectory reconstruction
Common questions
What advantage does a laser trajectory kit have over rods or string?+
A laser beam does not sag or bend under gravity over long distances the way a rod can, and it produces a cleaner, more precise line for photography without physically disturbing the bullet holes.
Does using a laser trajectory kit change the underlying reconstruction methodology?+
No, it is a documentation and visualisation tool; calculating trajectory angles from entry, exit points or defects works the same whether a rod, string or laser displays the line.
Related terms
- Angle of Impact
- The angle between the bullet's trajectory and the surface it penetrates, measured from the surface plane. Calculated from entry-hole geometry: sin(angle) =...
- Bullet Wipe (Metal Wipe)
- The grey-black ring of bullet-jacket material (grease, metal oxides, carbon) deposited around the margin of an entry hole as the bullet's periphery...
- Burke and Rowe 1992
- The primary peer-reviewed study of bullet ricochet behaviour on concrete, asphalt, and vehicle metal surfaces, published in the Journal of the Forensic...
- Faro Focus 3D
- A terrestrial laser scanner used for crime-scene documentation, capturing a full-resolution point-cloud model of the scene at millimetre accuracy. Trajectory rods or...
- Keyhole Wound
- An asymmetric teardrop-shaped bullet entry hole produced when the bullet strikes the surface sideways or is unstabilised, indicating close-range fire (pre-stabilisation) or...
- Ortho-Tron Projection Rod
- A commercial trajectory rod system manufactured by Sirchie, widely used by the FBI Evidence Response Team and forensic laboratories internationally, providing standardised...
- Ricochet
- The deflection of a bullet off a surface at a low angle of incidence, producing a new trajectory that diverges from the...
- Single-Bullet Trajectory Analysis (JFK/HSCA)
- The 1979 House Select Committee on Assassinations photogrammetric reconstruction of the Kennedy assassination trajectories, the most extensively reviewed shooting reconstruction in forensic...
- Trajectory Rod
- A rigid fibreglass or aluminium rod inserted through a bullet wound channel and aligned with the channel geometry to define the bullet's...