It's probably someone you know if they are stalking you like that. I'm not sure I understand why you want to track this person though. Why can't you just moderate your comments and delete anything that this person posts? You'll have a hard time tracking someone like that down.
If you get any threats, then I do suggest showing it to the police. You may be able to get microsoft or google involved to cancel the account, but the services are free and they would probably just sign up again. Also, because of the privacy policies in place, they may not be willing to help you at all.
I think it's off topic and spammy because of the title. You essentially ask people to do hacking for you. That's not what this site is about. If you had worded the title differently, it probably wouldn't have been deleted.
You could try reposting. I would suggest a title of "Ask YC: What should I do about a stalker on my blog?"
If you get any threats, then I do suggest showing it to the police. You may be able to get microsoft or google involved to cancel the account, but the services are free and they would probably just sign up again. Also, because of the privacy policies in place, they may not be willing to help you at all.