Hold people liable for encouraging crime and not reporting to authorities when they can stop it or at least try to stop it.
The Oregon shooter was encouraged by his online friends to carry out his murders and they should be just as guilty as him.
They could have contacted authorities and it would have never happened.
Instead they encouraged him to do it, that's like asking someone to go kill someone else.
They were all a part of his murderous plot and therefore justice should be served for the families of the fallen.