Well, there are even more tons of "confessions" of the accused that "confess" NOT being part of the coup. I hope you'll give them the same weight as the opposite confessions.
However this Doesn't mean that particular groups was not involved or took the initiative, I hope more will be revealed in time.
The problem is about prosecuting 99000 teachers, academics, and other "inconvenient" people, without much more than a hint that they do not like you or that they make fun of your similarity with Golum.