Green’s Dictionary of Slang

(US black) the police.

1971		E.E. Landy Underground Dict. (1972).
1980		E. Folb Runnin’ Down Some Lines 2: Irvine done vamped on me and my partner. [Ibid.] 243: irv Police.
1996		Eble Sl. and Sociability 83: There are 8 terms for ‘policeman’; including bluebird, Irvin, and skull-buster.