Green’s Dictionary of Slang

(US police) a general alert, a search for a missing person.

1953		Mad mag. Jan.–Feb. 3: We got an A.P.B. on the M.O. from the P.D.Q. on the B.V.D.
1967		M. Braly On the Yard (2002) 239: The police [...] put out APB’s on Caterpillar and Chilly.
1975		D. Goines Inner City Hoodlum 187: They issued an A.P.B. for the little black man they called Sam.
1987		‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 23: Last week the drive-in owners of Dallas County put out an APB on Joe Bob Briggs.
1996		Steve Earle ‘Billy and Bonnie’ 🎵 Now Billy wasn’t sweatin’ no APB.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 81: A six-foot-four nigger in an easily identifiable hot rod and a tristate APB out.