Green’s Dictionary of Slang

a police officer (usu. male), esp. a detective.

1959		E. De Roo Go, Man, Go! 149: If you ain’t get a search warrant, Dick Tracy, don’t search!
1969		J. Crumley One to Count Cadence (1987) 220: You know what that mother said [...] That crooked fucker [...] that head Dick Tracy.
1984		J. Ellroy Because the Night 203: ‘No shit, Dick Tracy?’ ‘If I'm lyin', I'm flyin'. Talk, Hubert’.
2000		M. Collins Keepers of Truth 164: And, damn it if you’re not a regular Dick Tracy, Bill.
2021		P. Papathanasiou Stoning 156: ‘Look, Dick Tracy, save it. [...] I didn’t kill her’.