Men, how do you get an ex to leave you alone?

So I have an ex-boyfriend who I had broken up with over two years ago. Periodically, he messages me asking for casual hook ups, meet ups, or to just talk.
To clarify, this ex and I did not break up on good terms and I?ve asked him on multiple occasions to leave me alone. Whenever he messages me, I used to ignore them and block him.
But things have changed now. He keeps on creating new numbers and new facebook accounts to contact me. I?m at my wits end and finally messaged him back saying, ?I?ve asked you on multiple occasions to leave me alone and to never contact me again. I have screenshot our conversations and if I hear from you again, I will notify the police for harassment and stalking.?
He replied, ?Lol, go ahead and try it. I?m going to do what I want.?
So I blocked him again. Thankfully he doesn?t have my address and I worked hard to scrub my name offline from those stupid people searching websites. But now I?m worried. How should I proceed?


Source.