Ex employee gives life threat and sabatoged office.

One of my ex employee (delivery boy) had left the job 3 months ago after working with us for 5 years. He wanted to start ola cab business and was not satisfied with the salary of 8500 per month. In the last one month he has been stalking my staff and picks up random fights with them and always hits them with his shoes or threatens them - all the time he is drunk. Yesterday he barged into my godown and hit one of the guy with a shoe so we called his father as his family stays nearby and asked him to explain him not to do anything stupid else we will register a police complaint. He came to our office today evening all drunk and while talking to my father he hit me while i was recording what he was saying. Later when his father was called even in front of him he hit me several times and manhandled my father. I had calles the police however they reached 5 mins after he left after threatning to kill me today or tomorrow. We lodged a police complaint against him he was kept in the police station was left off at 11 pm after a warning. At 11:05 pm he called my staff who stay in a nearby quarter given to them and threatened them that he will come tomorrow morning to to find out who complained against him and take revenge as he is now free. Me, my staff and family are under fear what can be done? His family has given up hopes on him they say let police beat him up and jail him. Most of my labor class staff in factory is from outstation and are very scared. What can be done and how can we deal with this situation?