The House Subcomittee on Assassinations in the 1970's determined the JFK assassination was a conspiracy, they just didn't determine who did it.
I'm not sure what you consider mainstream of official, but I don't think there is a real mainstream or official view. I have read lots of Cold War histories and there isn't a clear historical consensus on who killed JFK. Certainly not on who actually pulled the trigger.
The question of who killed JFK is a historical question now. In the past it was a whodunit, or a murder mystery, but that this point it is definitely a question of history that will forever be debated by historians.
Is there link to a good source on this. That's pretty much my understanding and it would be nice to have a good reference to counter the lone gunman idea.
Bullshit. "Everyone knows" there was one shooter: Oswald, and he was killed.
So he claimed, yes.
But the "benefit of the doubt" isn't necessary here. The theory that CIA recruited Oswald specifically to assassinate JFK has been conclusively proven wrong. The magic bullet theory has been conclusively proven wrong. That the USSR had evidence that the CIA assassinated JFK has been conclusively proven wrong. This has been studied in tedious amount of detail.
A little too convenient, don't you think?
Ruby was not afraid of the consequences? He couldn't wait for the judicial system to pronounce the death sentence? (which was very likely if Oswald was indeed the killer). If he loved the president so much, didn't he want to know if there were others involved, so they could be punished as well?
I think it is very unlikely that Jack Ruby's actions were borne of impulsiveness.
Jack Ruby was once again let to die in a prison before he could testify in a proper court. So many convenient ends disappear...