I'd do what Emily suggested and put a note (make a copy of it for yourself and to show to the police) that clearly states:

I've noticed the attention you've paid me in the past two weeks since you've moved in here. Let me be clear -- this attention is unwanted and unappreciated. I am asking that you stop this behavior immediately as it is making me feel uncomfortable. If you continue with this attention, I will have no choice but to involve the police in this matter. Thank you for your cooperation.

Don't hedge and don't apologize for your feelings. Make it absolutely clear to him that his advances are unwanted. In my suggestion, I also made it clear what would happen if his behaviors continued, but tried to be pleasant in the way I framed it. Use your own words and say what is comfortable for you to say. Don't forget to make a copy for your records!

Then, understand, if he continues you absolutely should followup with the police and even, if necessary, take it one step further and file a restraining order against him.

Sorry you have to be dealing with this... Nobody should have to feel this way in their own home. Life's usually not boring, now is it?

DocJohn