Environmental Control Stub
Definition
A blank carbon-tape stub collected from the collection environment (table surface, custody cell, vehicle seat) to establish background particle levels in the case-specific setting. Required by ASTM E1588-20 and ENFSI Best Practice Manual.
- Purpose
- Establishes background particle levels at the scene
- Required by
- ASTM E1588-20 and ENFSI Best Practice Manual
- Sample type
- Blank carbon-tape stub
Common questions
Why is a control stub taken from the environment, not from the suspect?+
It answers a different question than a suspect's hand or clothing sample: whether the collection setting itself (a table, a custody cell, a vehicle seat) already carries particles resembling gunshot residue, which would undermine confidence in a positive result from the suspect sample.
What happens if the environmental control comes back positive for GSR-like particles?+
A positive control weakens the evidential value of any matching particles found on the suspect, since it raises the possibility of environmental contamination rather than firearm discharge or handling as the source.
Related terms
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- Carbon-Tape Stub (Tri-Mark)
- A standard SEM-format aluminium or plastic pin stub bearing conductive double-sided carbon tape, used to collect GSR from hands and surfaces for...
- NABIS (National Ballistics Intelligence Service)
- The UK agency responsible for managing ballistic evidence including GSR analysis, operated by the National Police Chiefs' Council. Issues guidance on GSR...
- Persistence Half-Life (GSR on Hands)
- The time after which approximately half of the initial particle count has been lost from the hand surface. Published studies (Cardinetti 2004,...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...
- Tertiary Transfer
- Transfer of GSR from a secondary surface (a person who received particles via handshaking) to a third surface. Documented at low levels...