>>2 My initial thoughts were to have written evidence, e.g. written confessions from the victims or screenshots and photos of the events happening and placing them in a folder to be placed somewhere nearby the administration office. You could place an 'urgent' or 'for authoritative eyes only' header on the file for it to be read immediately. Preferably audio and video would be better evidence, but for that you'd need to set up a new phone number or a different social account to send it as to avoid any suspicion towards you.
I would really like to know if there is a more efficient way of providing anonymous evidence. If you have ideas, please do spill.