Creepy guy at the library?

File a restraining order. I don't know what country you live in but if its in the US go to the court house in your county or the county where the abuse takes place (harrasement is abuse). Tell them you need to file a Civil Harassment Orders against a man, you do not know him, he follows you around and stalks you, you have made reports to the police but they don't do anything. You'll fill out a petition for a restraining order and an affidavit that explains what happened during the abuse situation. You will need to provide information about the other party's appearance, home and work address, and abusive actions. If possible, bring the following documents to give as detailed a report as possible bring a photograph of the person, the next time you see him snap his picture with your phone or camera, bring any police reports you've filed and ask the library staff to sign statements that you've made complaints to them as well. You should get results on a hearing date within a few days, if you need an immediate restraining order ask for a temporary one that they can give you immediately. If you do not know who the person is you must fill out special paperwork stating this since he has to be handed paperwork on the restraining order by the court for it to be valid. You must do something the reports they are making wont do any good when he rapes and kills you now will they. He needs to be told to leave you alone or he'll have serious consequences. If he violates the restraining order call the police immediately and make sure to always carry the paper with you!

ask the police to take proper action or else go to some higher officer