I don’t even know who it is?

This account has started harassing me via DM. I don’t have screenshots of the convo because the thread disappeared when the account blocked me. I have zero clue as to who it is. I’m generally a well-liked person and keep my profiles private(don’t add randoms or people I don’t personally know) so they really went out of their way.

I might be able to get the account taken down, but that doesn’t help if they can just make another one and harass me all over again. I’d like to take this up with law enforcement, but I have to know who’s behind the account. How do I figure this out y’all?