Hire a private detective? Other than that you’re pretty screwed unless this person has wronged you in some way. If that’s the case you can call non-emergency, explain your situation and a cop will tell you what you need to know. When I had a stalker, I was able to find out about past offenses, what his real name was and where he lived. Depending on whether or not you get an address probably varies from cop to cop, too. There is a website that you can pay to get info on people by using their plate number, but the Drivers Privacy Protection Act prevents most people from obtaining such information. The site might be there to steal your money, and apparently they can only search in Colorado, Florida, Minnesota, Mississippi, Missouri, North Carolina, Ohio, Tennessee, Texas, West Virginia, and Wisconsin. If you’re not from any of those states, I don’t suggest trying it. I also may not try it simply for the fact that they probably rip you off. May I ask what you need such a service for?