How to expose an abuser?

I was wondering if anyone here knows of ways to expose someone who is abusing you, or to trick that person into publicly confessing, especially if you have no concrete proof and the offender is somewhat famous with money and other famous co-abusers/enablers to protect him. (E.g. are there any psychological techniques to make a liar confess in an email or on an online video. In this scenario, using a tape recorder or smartphone is impossible/dangerous).