Lying in perpetuation of a coverup is the virtual definition of a co-conspirator.
No it isn't.
Conspiracy requires communication between the perpetrators. If someone on this thread knows that Burke is guilty of the crime by some kind of inside knowledge -- maybe one of his girlfriends is a FReeper -- say, and falsely posts that he's innocent, she is not a co-conspirator. She is simply someone withholding evidence and lying about that. Possibly this is a crime depending circumstances and the laws governing hearsay in a particular jurisdiction, but it is not conspiracy, per se.
Burke is also not part of a conspiracy, since he could not have been part of a conspiracy as a nine year old. His ongoing lies do not draw him into the planning of the commission of any future crime, unless he and his father or older half-brother have actually discussed the cover-up along with plans to continue it. Without coordination and a plan to commit a future crime, there is no conspiracy.