Keyhole Defect
Definition
An asymmetric gunshot defect produced by a projectile striking bone at a shallow angle; one end shows a conventional beveled entry geometry and the other shows a tangential groove or shallow furrow, with the long axis of the defect pointing toward the direction of fire.
- Location
- Bone, typically cranial
- Cause
- Shallow-angle projectile strike
- Feature
- Beveled entry at one end, tangential groove at the other
- Interpretive value
- Long axis points toward the direction of fire
Common questions
How does a keyhole defect differ from a standard entrance wound in bone?+
A typical entrance shows internal beveling around the whole margin, while a keyhole defect shows that beveling only at one end because the bullet grazed the bone at a shallow angle rather than striking it perpendicularly, leaving a shallow furrow along the rest of the defect.
Can a keyhole defect alone determine bullet calibre?+
No. Its shape mainly informs the angle and direction of impact rather than calibre, since a grazing or ricocheting bullet can produce a similar elongated defect across a range of calibres, so calibre estimation still needs measurement of the more circular beveled portion or recovered fragments.
Related terms
- Bearing Surface Diameter
- The diameter of the projectile face in contact with the bone surface at the moment of impact; smaller than the resulting defect...
- Contact Wound
- A firearm wound produced when the muzzle is pressed against or within a few centimetres of the target surface. Characterised by a...
- External Beveling
- The cone-shaped defect geometry at an exit gunshot wound in bone: the inner table diameter (entry face of the defect) is smaller...
- GSR (Gunshot Residue)
- Primer-combustion products (classically lead-barium-antimony compounds, now also non-lead formulations) deposited on the bone surface at close or contact range; detected by SEM-EDX...
- Internal Beveling
- The cone-shaped defect geometry at an entrance gunshot wound in bone: the outer table diameter (entry face) is smaller than the inner...
- Puppe's Rule
- The 1994 formalisation of the principle that radial fractures from a subsequent gunshot terminate at fracture lines already produced by a prior...
- Secondary Projectile
- A bone fragment or other material driven at high velocity through adjacent tissue by the primary projectile's passage through bone; produces irregular,...
- Stellate Fracture
- A set of radial cracks extending outward from the main gunshot defect, produced by compressed propellant gas pressure radiating under the scalp...
- Trajectory Reconstruction
- The forensic procedure that integrates the osteological bevel direction, angle-of-impact estimate, and the physical scene evidence to reconstruct the relative positions of...