It depends. If it was a criminal act, report it to the police and wait for the result of any criminal prosecution. If the verdict is guilty, you are free to talk about the results and refer to any publicly available information. Beyond that, disputes between adults should be settled privately. If you are asked to give reference for someone you had a problem with, you can either decline to comment, say you do not recommend working with this person without giving details, or give your account of what happened.
Never start a rant in a public forum trying to make you feel better or trying to tear down the other person. In almost all cases, your reputation will just be as tainted as the one you are accusing.