she should contact the police, sexual assault of any kind and stalking are both illegal criminal activities, if he is going into her work someone will know his name, right, find out that way from her workplace and then go to the police. what is she waiting for to be abducted, raped or murdered? this is what the police are there for, call them, they can find out who he is for you if you can't.
When I tell the truth, it is not for the sake of convincing those who do not know it, but for the sake of defending those that do.
William Blake