In answer to some of your questions, apparently a lot of former staff members who quit working there because of the atrocities committed against the "students" are afraid to tell what they saw, or at least put a name and face to their statements, because of confidentiality agreements that are the terms of employment. Basically, even if you quit and you go and talk about it, you can get into legal trouble. Kudos to someone with the guts to risk it anyways in the name of exposing these bastards, though.
What I'm surprised about this is how, at least as I remember reading, the center was ORDERED to keep these tapes available for further investigation/evidence, and "accidentally" destroyed them anyways, and yet they remain unpunished for it. But then again, I've heard these guys have all sorts of corrupt ways of working and connections to help them get away with it.