By no means. We don't have the suicide note found in Cho's dorm room, and we only have NBC-filtered commentary on the long letter he wrote to that network. Nor have all the videos been made available.
We do have a statement from authorities that there was no suicide note in the room, just a few pages of free-form rant.
I aways find that, when I'm going to commit mass murder and justify it with a rant, it's important to have a backup rant just in case the mail to NBC gets lost. His computer will no doubt have the files he sent to NBC.