Stokes- This stuff may vary by state. In NY at least liens have to be filed with the County Clerk. You can either check it yourself or, if significant money is involved and/or you want to be careful, you could have a title company check for you. Although I know how to do this (in NY anyway) I still usually use a title company for any serious work.
You can find them under title company in the yellow pages
Chicago Title may have an affiliate near you, I'm not saying that's who you should use though, but it's a start.