noun
special investigation department
Refers to a dedicated investigative unit, often within a police force or public prosecutor's office, tasked with handling major or complex cases.
特捜部が大規模な贈収賄事件の捜査を始めた。
The special investigation department has begun investigating a large-scale bribery case.
Compound of 特 (special) + 捜 (search/investigate) + 部 (department/division).