Any ideas for locating owner of vacant property?

[Chris Pizzulo]

Hi guys, I'm in need of some help. My girlfriends parents have a vacant house next door which could be very nice but it's been vacant for quite some time and it's showing the signs. I located the owners name via tax records and tried sending a yellow letter to the property address hoping it would get forwarded but it can back marked "Return to Sender - Vacant - Unable to Forward". Does anyone have any suggestions on how I might locate an address for the owner or get in touch with them? Thanks in advance.