In APCO, Association of Public-Safety Communications Officials 10-codes, 10-66 means "Suspicious Person" or "Subject Investigation". It is used to report an individual whose behavior, presence, or activities appear unusual, suspicious, or potentially related to criminal activity, enabling dispatch and law enforcement units to monitor, investigate, and respond appropriately.
Here’s how it might be used in a real-world scenario:
- Officer: "Dispatch, 10-66 at Main Street and 5th, subject acting suspicious near closed storefronts."
- Dispatch: "10-4, units in the area advised, maintain observation and report updates."
In this exchange, the officer reports a person whose behavior warrants attention but may not yet constitute a confirmed crime. Using 10-66 allows dispatch to alert other units, coordinate monitoring, and ensure officer safety during interaction or investigation.
Operational Purpose
10-66 is important for proactive law enforcement, situational awareness, and crime prevention. Rapid reporting allows units to document suspicious activity, assess risk, and respond effectively without escalating the situation unnecessarily. It also helps track patterns of behavior that could indicate ongoing or planned criminal activity.
This code is commonly used for individuals loitering in sensitive areas, behaving erratically, carrying unusual items, or otherwise drawing attention due to suspicious actions. It may also apply to reports from concerned citizens or business owners.
Officer Safety And Coordination
Declaring 10-66 ensures officers and dispatch maintain situational awareness and coordinate response safely. Units may report location using 10-20, acknowledge instructions with 10-4, or indicate temporary unavailability with 10-6. Proper coordination minimizes risk while observing, approaching, or detaining the subject if necessary.
Variations And Agency Practices
Some agencies use 10-66 for broad observational purposes, while others restrict it to potential criminal activity or threats. Local protocols may define documentation requirements, risk assessment procedures, and the use of backup, surveillance, or specialized units.
Plain-Language Alternatives
Agencies emphasizing plain-language communication may replace 10-66 with phrases such as:
- "Suspicious individual observed."
- "Person under investigation."
- "Subject behaving unusually or suspiciously."
Related 10-Codes
Codes commonly associated with 10-66 include 10-4 (acknowledgment), 10-20 (location), 10-23 (arrived on scene/standby), 10-55 (intoxicated driver/traffic alert), and 10-50 (accident/crash report). Together, these codes support coordinated, safe, and effective monitoring and investigation of suspicious individuals.