In all honesty, I think the evidence of Oswald's involvement is quite significant and also can not be ignored. And by stating that he was a "patsy" he more or less admitted his involvement.

I believe that if there was a conspiracy (which I think there was) it must have been a very select group of people, probably no more than a couple dozen, for it to work. Within this group there were a few high-ranking mobsters and people who held key positions within the government, its agencies, the military industrial complex and the banking system, who indirectly (or perhaps even directly) control the government, and ofcourse a small group of assassins.

I really don't believe the mob could have done this on their own. Guys such as Marcello were too smart to make such a bold move without backing and assurance. So if the mob was in fact behind it, it automatically means that people who held key positions within the government or its agencies were involved as well, because only they would've been able to arrange for the cover-up.

The irony of the conspiracy theories is that it is a product that has been created by the government itself. Both the FBI and the CIA have been acting very suspicious in the aftermath of the assassination. This would've been unnecessary if there was no conspiracy of any kind. For example, the CIA made an incredibly strange move by showing a photograph of a man that was supposedly taken at the Cuban embassy in Mexico City and claiming that this was Oswald, while he clearly wasn't. They could've at least chosen someone would looked the part. What kind of game were they playing?