noun
detective; police detective
Refers to a police officer who investigates crimes. Often used in news and fiction.
刑事が現場に到着した。
The detective arrived at the scene.
彼は警視庁の刑事だ。
He is a detective with the Metropolitan Police Department.
noun, noun-modifying (irregular)
criminal matter; criminal case
Used in legal or formal contexts to refer to a criminal affair, as opposed to a civil matter (民事). Often appears in compounds like 刑事事件 (criminal case).
これは民事ではなく刑事だ。
This is a criminal matter, not a civil one.
刑事責任を問われる可能性がある。
There is a possibility of being held criminally responsible.