Persistence Half-Life (GSR on Hands)
Definition
The time after which approximately half of the initial particle count has been lost from the hand surface. Published studies (Cardinetti 2004, Koons 2002) indicate approximately 4-6 hours for conventional Pb-Ba-Sb GSR under normal activity conditions.
- Typical range
- Roughly 4 to 6 hours under normal activity
- GSR type studied
- Conventional lead-barium-antimony particles
- Source studies
- Cardinetti 2004, Koons 2002
- Major variable
- Level of hand activity after the shooting event
Common questions
Does washing or wiping the hands shorten the persistence window?+
Yes, deliberate washing, vigorous activity, or contact with other surfaces removes particles faster than the passive decay figures from controlled studies, so the published half-life applies to undisturbed hands, not to a suspect who has since washed.
Why do reports give a range instead of a single fixed persistence time?+
Particle loss depends on skin condition, sweating, clothing contact and hand use, all of which vary between individuals and scenarios, so a single number would overstate the precision the data actually supports.
Related terms
- 5% HNO3 Swab
- A cotton or polyester swab pre-wetted with 5% nitric acid, used to collect dissolved GSR for atomic absorption spectrometry or ICP-MS. Recovers...
- 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...
- Environmental Control Stub
- A blank carbon-tape stub collected from the collection environment (table surface, custody cell, vehicle seat) to establish background particle levels in the...
- 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...
- 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...