4. Except that no-one ever has come up with credible evidence.
The wounds and trajectory are consistent with shots fired from the sixth floor of the TSBD, and fired from Oswald's Carcano rifle. An examination of the physical evidence consisting of the wounds to Kennedy and Connally, of recovered bullet fragments, of the evidence of Oswald's rifle, of Oswald's movements immediately following the assassination (including his murder of a Dallas police officer), of his behaviour prior to the assassination (including his taking a shot at Gen Edwin Walker, and his leaving his wedding ring with his wife the night before the assassination), all lead to one conclusion; that Oswald did it, and he acted alone. The wishful thinking of people who refuse to accept that a loser with a cheap mail-order rifle could kill the most powerful man in the world doesn't change the basic evidence. And most of the conspiracy theories seem to be based on a deeply flawed and ahistorical understanding of Jack Kennedy, who was a McCarthyite Cold Warrior who believed in the "domino effect" in Southeast Asia, who was committed to the US mission in Vietnam, who wasn't trusted by the liberal wing of his own party, and who probably would have voted for Nixon if he hadn't gotten the Democratic nomination in 1960 (Bobby Kennedy did in fact vote for Ike and Nixon in '56, rather than for Adlai Stevenson). The idea of Kennedy-as-liberal-martyr on the altar of the military-industrial complex is so ludicrous as to not even merit consideration. The only really vaguely plausible conspiracy theory (which is totally unsupported by any evidence) is the idea that the Mafia were behind the assassination as revenge for feeling double-crossed after Mob associates of Joe Kennedy's swung the election by just enough in West Virginia and Illinois for JFK to eke out a win and then JFK's Justice Department went after them anyway.