There's no real proof either way. All we have to go on, is Big Brother & Idiot Box disinformation. No one here on this Board can prove anything either way. And that's the way it's supposed to be.
Proof is an elusive animal in any case; but the fewer the aspects in need of evidential support, the better.
Ever heard of
Occam's Razor?
The less 'elaborate' the hypothesis, the more plausible it is at base level.
In order to believe that the deaths of any or all of the victims didn't really happen, one would have to buy into the planners' capacity and desire to subvert the knowledge of MANY more people related to (or any way acquainted with) the victims in question, when simply carrying out the killings and framing a kid with a history of psychosocial issues would not only be easier, it would also lend an air of reality/credibility to the operation, all while calling for much less damage control in the aftermath.