It sounds very much like you're a whistleblower of some crime, which gives you protection against the sort of retaliation you're describing. See http://en.m.wikipedia.org/wiki/Whistleblower for more information about legal protection.

Now, you're not immune to workforce politics so there may still be reasons why you'd be fired but I definitely wouldn't accept it without finding out a lot more about your situation and potentially escalating the complaint.