It’s essential to know the identity of the accused person for any type of action. If you don’t know the person, you can present any proof which will help in identifying the accused. For example- if a person is harassing you via sending vulgar pictures and texts from random Ids, you should have the screenshots of the chats and discussion. CCTV cameras are there in the institute, so you may check whether it is there at the point of the incident. All efforts will be made to identify the culprit.