Locard Exchange Principle
Definition
The forensic principle that contact between two surfaces transfers material in both directions. Plant material, pollen, seeds, and leaf fragments all transfer from environments to people and objects, making botanical evidence a direct expression of this principle.
- Core claim
- Contact between surfaces transfers material both ways
- Botanical expression
- Pollen, seeds, leaf fragments transfer person to environment and back
- Field
- General forensic science principle
Common questions
How does Locard's principle apply specifically to botanical evidence?+
Plant fragments, pollen, and seeds adhere to clothing, footwear, and vehicles from an environment, and conversely a person moving through a scene can deposit foreign plant material there.
Is transfer under Locard's principle always detectable afterward?+
No. Transferred material is not always retained, persisted, or recovered; its usefulness in a case depends on the separate transfer, persistence, and recovery framework applied to that evidence type.
Related terms
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