Was there a great bit of CYA at the FBI after the fact because of their failures to spot and stop the freak? Certainly. It is would be surprising if the CIA wasn't involved in some CYA as well.
@John_Scotus I remember years ago the stories coming out how J. Edgar hated the Kennedy family and he might have been in on it.
But this is not equivalent to conspiracy to kill Kennedy. Nor is it really even news.