> If it turned out that there was a conspiracy it is actually quite likely that the group that organised it are still active.
I don't think these are correct assumptions. Sixty years is a long time, and the world has changed a lot. The Soviet Union is a shell of its former self (hence the current Ukraine conflict), Fidel Castro is dead, etc.
> if it was the Israelis
IMO this is one of the dumber and least plausible of the conspiracy theories.
What are we even to conclude from this, though? Of course Israel still exists, but what exactly are you trying to imply about the current situation? Netanyahu, by the way, was 14 years old in 1963 and was actually living in Pennsylvania, US at the time.
> there'd be no reason to believe they stopped
Stopped what?