Green’s Dictionary of Slang

(US Und./police) a pickpocket or petty thief.

1950		Goldin et al. DAUL 111/2: Jostler. A pickpocket’s helper who jostles and distracts attention of victim.
1956		(con. 1940s) J. Resko Reprieve 182: The jostler’s task was distracting the victim’s attention, while the hook [...] extracted the wallet.
1965		C. Brown Manchild in the Promised Land (1969) 168: After a while, you got to know all the jostlers down there.