Passive Alert
Definition
A trained response in which the dog sits, lies down, or freezes at the scent source without digging or pawing. Preferred in forensic search because it does not disturb potential evidence at the deposit location.
- Behaviour
- Sit, lie down, or freeze at source
- Field
- Canine search
- Preferred for
- Preserving evidence at the deposit site
- Contrast
- Active alert, e.g. digging or scratching
Common questions
Why is a passive alert preferred over an active alert in evidence searches?+
A passive response does not disturb the ground, container, or item at the source, preserving trace and physical evidence at the exact deposit location for later recovery and documentation.
When is an active alert still used instead?+
Active alerts, such as scratching or digging, remain standard in some narcotics and explosives detection programs where speed of location matters more than preserving the immediate deposit site.
Related terms
- HRD Dog
- Human Remains Detection dog: a dog trained to detect and alert on the volatile organic compound signature of decomposing human tissue. Also...
- Scent Cone
- The plume of airborne VOC molecules that diffuses upward and downwind from a buried source. A dog working downwind of a buried...
- Search Pattern
- The systematic geometric route walked by a dog handler to ensure uniform coverage of the search area. Standard patterns include the ladder...
- Tile Probe
- A solid steel rod used to probe suspect ground by hand pressure, detecting resistance changes in disturbed soil and releasing sub-surface gases...
- VOC (Volatile Organic Compound)
- Carbon-containing compounds that evaporate readily at ambient temperatures. Decomposing human tissue produces a complex, changing VOC mixture that HRD dogs are trained...