How can I handle a male supervisor who has wanted me for over a year and refuses to back down.?

I have a former supervisor at work who took a strong liking to me about a year and a half ago. He insisted on offering tons of help and was very strict. Eventually he began hitting on me, telling me I shouldn't disrespect him because of "everything I've done for you." Before long he took to calling me Casanova. After I broke up with my girlfriend he began more directly and aggressively to pursue me. I broke off ties and when the situation worsened, I submitted a complaint to HR. Despite my complaint he has yet to back down. After the complaint although he hasn't said anything to me I've spotted him staring at me from across the office and he has been walking close to me to the point that our bodies almost touch. I've talked to a friend who has said that he is going to continue his behavior even if he is fired. I've asked for mediation at work since they don't seem to be able to handle it but it hasn't come to be. Does anyone have any options on what I should do?