There is no evidence on who he stole that Rolls from, but he was pretty blatant about it, and who knows if the deal was really collateral for work or money, or features, or what kind of tangled web is beneath. It could be as simple as he met someone, gained their trust, in some dubious way, and just thought there would be no discussion.
Gut feeling is it was a civilian, moreso than an active criminal, as the Brooklyn US Attorneys Office got involved, or maybe it was someone pretty sophisticated, who knows how to play that game, and sent a lawyer, but still, why then kill him?
I think at this point robbery is the most likely motive, until further evidence is discovered. To people looking it seems random that one person is killed, out of 6 in the house, but we don't know these factors
How many people WERE actually in the house?
How many people with guns?
If there is one person with one gun, (suspects) out of 4 and 6 potential victims the odds are still pretty reasonable to think Smoke was just happenstance. 1 in 10 or 1 in 20, less so. But, we don't have this info.