Found an Abandoned House - How do I find the owner??

[Boris Peyzner]

Hello All, 

I have found some abandoned houses and have identified the owners name.  The problem is that I do not know where the owner currently resides nor do I have a phone number.  In the past, I hired a private investigator to locate this information for me.  The problem is that the private investigator charges about $40 a name.  While this is acceptable when I am targeting one specific house, it is more then I want to  spend when I drive a city and find 100 potential houses.  Does anyone know of any tools that are available that can be used to identify a person's updated mailing address or better yet a phone number?