Scared of customer whos trying to befriend me with violent history and isn't stable mentally.

I work in retail and have had this guy coming in recently. He seemed nice enough and after a couple months of coming in time to time chatting asked to hang out. He seemed a little weird or off but wasn't ever rude to me or caused any issues so I try not to judge. We exchanged numbers and that's when things got weird. He called me basically right away to make sure I got the text. I said I did and that was all fine. After a few days I started to see post about him on Facebook and how he was recently charged. I can't even remember what it was for but I know he had caused issues in some other business and actually made someone quit and is hiding from them.

They have started calling me and texting all the time. I explained that I saw the post and I can't involve myself with that. However they didn't seem to understand and have continued to message me and saying really weird things about being able to help me if someone ever fucks with me and other things.

I haven't responded to any of the text's and only had the 2 calls with him. However, I'm fucking scared of this guy and i dont' know how to get rid of him. He now has my number and knows where I work. The police won't do anything unless he does something so that's not an option. It fucking terrifies me and nothing has even happened yet but I can tell this guys is not right in the head. I don't know how i didn't see it sooner. I don't know what to do. All the texts hes sending are giving me anxiety and I'm terrified to go to work