noun
G-man; FBI agent
Specifically refers to a special agent of the FBI, often with a tough, investigative image. The term is borrowed from American English and carries a similar nuance.
あの映画の主人公はＧメンだ。
The protagonist of that movie is a G-man.
Ｇメンが組織犯罪を追っている。
The G-men are pursuing organized crime.
noun
inspector; government investigator
Extended use for any government inspector or investigator, not limited to the FBI. Less common than the specific FBI sense.
税務署のＧメンが調査に来た。
An inspector from the tax office came to investigate.