i've seen this kind of case before. she can file

a harrassment case to HR. however it would just end there. since the harrassment case is classified based on the repetitive pattern. so if he stops that behavior at some point, the case is closed. unless you, or someone else, reopen the case, saying he's doing it again. otherwise, it is just that.

as far as sue him in court, forget about it. it will only give you loss of money and huge anger. on court, the result is solely dependent on the skills of your lawyer. i won't bet on that your lawyer is better than company's lawyer.