JFK was almost certainly the victim of a murder plot enacted by a faction of the federal government... Most likely because he intended to take down the federal reserve and limit the scope of the CIA's power. Basically his intent was to dismantle the military industrial complex that currently is in full steam ahead mode.

Oswald was obviously involved, to what degree (I suppose) is still a mystery. His comment of being a "patsy", is more or less an admission of pre-knowledge of the assassination, however I find it highly unlikely he acted alone. I'm not saying that there were other shooters, just that there seems to be a hidden hand directing him.

And of course, what is the first rule of assassination? Silence the assassin.

I doubt the mob was in anyway involved to be honest.