There’s plenty of evidence that suggests that others were involved but no smoking gun or conclusive proof.
Speculating about a conspiracy is not the same as proving that there was a conspiracy.
We may never be able to answer the questions of whether there was or wasn’t a conspiracy.
The case is not closed.
There are quite a few intriguing circumstances which create the opportunity for speculation about conspiracies. And for many years I just “knew” that there HAD to be a conspiracy. Learning more details, with an open mind, has changed my mind. And the more I continue to learn, the more convinced I am. That said, I am open to any new evidence of a conspiracy. I believe that most others are also.