Department of Special Investigation

The Department of Special Investigation (DSI), under Thailand's Ministry of Justice (MOJ), operates independently from the Royal Thai Police (RTP) and is responsible for tackling high-profile crimes and transnational criminal enterprises. Its mandate includes against transnational organized crime, counterintelligence, counterterrorism, and investigating complex cases that impact national security, involve organized crime, or implicate high-ranking officials and law enforcement.

It has its own police tactical unit (PTU) called DSI Special Weapons and Tactics (DSI SWAT) Teams aka Indiraja 10, falling under the Bureau of Special Operations. DSI SWAT Teams is used for high-risk tactical law enforcement situations such as anti-irregular military in urban areas, apprehension of armed and dangerous criminals, executive protection, hostage rescue, support urban counterterrorism, and other tactical special operations.

DSI SWAT often joint training in tactics with the police tactical units of the Royal Thai Police, which mostly focuses on training in urban counterterrorism and hostage rescue crisis management. The police tactical units that frequently participate in joint training include Arintaraj 26, Counter Terrorism Special Operations Unit, Hanuman, and Sayobpairee 43. As for other law enforcement agencies that also joint training in tactical include the Eagle 19 Special Operations Team (Eagle 19 SOT), a police tactical unit under the Office of the Narcotics Control Board (ONCB). In which the joint training focuses on apprehension of armed and dangerous criminals involved in narcotics, including hostage rescue if the perpetrators capture hostages to use as human shields.

As of June 24, 2020, the DSI has also been assigned to investigate cases under the Prevention and Suppression of Torture and Enforced Disappearances Act, once enacted, focusing on incidents of torture and forced disappearances.

The DSI is often regarded as Thailand’s equivalent to the United States’ Federal Bureau of Investigation (FBI). Since its establishment, it has faced ongoing jurisdictional disputes with the police, with tensions arising over authority in high-profile cases. Additionally, DSI officials have repeatedly voiced concerns about political interference, which they claim has hindered the department’s ability to operate independently and effectively.