Green’s Dictionary of Slang

1. (US Und.) a steamboat thief, spec. the thief who actually removes the booty.

1837

N.Y. Times 16 Aug. 2/6–7: Frequently a gang of half-a-dozen [thieves] combine together. Part of them act as ‘jackals’, and the others as receivers. These latter gentry take care to be on the wharf on the landing of the boat, ready to receive the booty provided by the jackals.

2. a moneylender’s tout.

1898		Binstead & Wells Pink ’Un and Pelican 202: Flash had an extensive ‘practice’ as a jackal (a money-lender’s tout, for the benefit of the groundlings).
1933		C. Drew ‘Sledgehammer Joe’ in Bulletin (Sydney) 19 July 49/1: Just before the boxers entered the ring I chatted to a chap I knew, and he went round among the jackals to get our money on.