It's a fair question, Osa. I can see why you would ask it, I mean, we want our news and information to have come from reliable sources and we cannot accuse people, organizations..etc without having real proof.
But I wish to point something out, which I am sure that you yourself probably already know, and that is this: the intelligence communities (the FBI, CIA, or the CSIS in my country) engage in a lot of covert operations. They hide any trails that might lead back to them. They cover their tracks. They engage in false flag attacks. They put sleeper agents in various places. They stage sting operations that are almost indistinguishable from entrapment. They employ nefarious, asymmetrical tactics. In other words, just because there is no proof, that doesn't mean they didn't do it. I know this is very unsatisfactory, but I need to say it.
I am not trying to prove any wrongdoing. I simply do not have any proof. But I want to convey to the regular Americans that they need to do something that is very alien to their nature, and that is they need to be a little on guard, a little suspicious, with their government, but especially when it comes to the feds.