Army Tactics, Techniques, and Procedures (ATTP) 3-39.20 is the manual for police intelligence operations (PIO) doctrine. This manual aligns with Field Manual (FM) 3-39, the Military Police Corps Regiment's keystone manual, and other Army and joint doctrine. Simultaneous operations that combine offensive, defensive, and stability or civil support operations are emphasized. PIO is a military police function that support the operations process and protection activities by providing exceptional police information and intelligence to enhance situational understanding, protection of the force, and homeland security HLS). This manual emphasizes that PIO supports, enhanced, and contributes to the commander's protection program and situational understanding by analyzing, integrating, and portraying relevant criminal threat and police information and intelligence that may affect the operational environment (OE). This threat information is gathered by military police Soldiers as they conduct military police functions and by other Army Soldiers, Service policing forces, multinational elements, and security forces. This manual is written for military police and United States Criminal Investigation Command (USACIDC) Soldiers and civilians conducting the PIO function. This manual is focused on establishing the framework of PIO, how PIO supports military police and Army operations, and how to integrate PIO within the other four military police functions: Law and order (L&O), internment and resettlement (I/R), maneuver and mobility support (MMS), and area security (AS).