Green’s Dictionary of Slang

1. (UK Und.) that member of a pickpocketing or shoplifting team who takes the stolen item from the person who actually picks the pocket.

1591		Greene Second Part of Conny-Catching in Grosart (1881–3) X 118: The Lift attired in the forme of a ciuell Country gentleman, comes with the Marker into some Mercers shop [...] and there he calles to see a boult of Satten.
1608		Dekker Belman of London G3: He that receiues it is the Marker. He that stands without and carries it away, is the Sentar.

2. (US black) a person engaged in ritual teasing or mocking.

1972

Mitchell-Kernan ‘Signifying, loud-talking and marking’ in Kochman Rappin’ and Stylin’ Out 333: ‘Marking’ is essentially a mode of characterization. The marker attempts to report not only what was said, but the way it was said, in order to offer implicit comment on the speaker’s background, personality, or intent.

3. (US black) the bait that lures a victim into some form of swindle or other fraud.

1983

R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].