Property Liens

I need to know if there are liens on a preforeclosure property. When I go to our assessors site, they do have a link that tells us the property tax information but there is nothing about mechanics liens, child support liens, etc. Is there a way to find that out online? Is it free info? I realize a title search will eventually have to be paid for should I pursue a property but would like to use that lien info to either eliminate a preforeclosure lead or use it in negotiation a price. I live in Iowa if that makes a difference.