Otherwise we fall into the pit of using "negative evidence" to assert guilt. May I remind you that the New York Times, Los Angeles Times, Chicago Tribune and Washington Post were NOT ATTACKED! And the premier left-wing media institution in the US, National Public Radio, was likewise not attacked.
Does that mean they engaged in a conspiracy against the two major tabloid format publishers - the New York Post and AMI (National Enquirer)?
It does not. And the same goes for the idea that some right-wingnut did the job.