Earlier today I was doing Merl Reagle's crossword and one of the clues was "Fraud fighting Fed." The answer turned out to be "T-Man," being short for "Treasury Man." So, this got me thinking...
Though the slang term "G-Man" is short for "Government-Man," it seems exclusively used to describe FBI agents. I think I understand why this is the case (given the origin of the term and its subsequent dramatization in popular culture).
However, many departments within the U.S. Government fight organized crime and conduct criminal investigations. With that in mind, can, for example, a CIA operative be considered a G-Man? Or a Secret Service agent?