TPR Framework
Definition
Transfer, persistence, recovery: the three sequential filters that every trace passes through, and the lens analysts use to weigh what a positive or negative result actually means.
- Components
- Transfer, persistence, recovery
- Purpose
- Weigh what a positive or negative trace result means
- Basis
- Sequential application of Locard's exchange principle
- Application
- Trace evidence evaluation, e.g. fibres, soil, gunshot residue
Common questions
Why can a negative trace result not be treated as proof of no contact?+
Absence could reflect failure at any of the three stages: material never transferred, it transferred but did not persist through subsequent activity, or it persisted but recovery technique missed it. The framework forces analysts to consider all three before concluding no contact occurred.
How does persistence differ from transfer within this framework?+
Transfer is the initial deposit of material at the moment of contact. Persistence is whether that material survives the time and activity between contact and recovery. A strong transfer can still yield little evidence if persistence is poor.
Related terms
- Exchange Principle
- Locard's core idea that physical contact between two surfaces moves material in both directions, so a perpetrator both deposits and removes trace...
- Persistence
- The property that friction ridge configuration remains stable from birth through death and into decomposition, as long as the papillary dermis survives....
- Primary Transfer
- The direct movement of biological material from an animal to a surface it contacts. When a dog sheds hair onto its owner's...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...
- Trace Evidence
- Small quantities of material transferred between people, objects, and locations during contact. Forensic geology focuses on the geological subset of trace evidence:...