You've hit on one of my company's most successful marketing tools. You may have a hard time tracking the owner through public records. Owners of long-vacant homes are usually in an assisted living facility, deceased, or out of the area. Sometimes they have a local attorney who looks after the house, though by the look it they're not earning their $450/hour. Most owners either have no family or their family lives far away (I've travelled to the midwest more than once to present an offer for a boarded-up property).
We have a lot more success with just asking the neighbors. They may know the owner or an owner's family member and agree to give you contact information. While I would never open a mail box or do anything else ILLEGAL (tampering with the mail is a federal offense, entering without permission is trespassing...), I've had luck just looking at mail on the ground or stuck in the door to get a name, which may or may not match the real owner. Just follow the leads.