The notices have the property address where you can then go into the county assessor' office and pull up that address and hopefully get a situs and mailing address that you can send letters to.

I'd hold if the situs is right. 

I think part of why it is so confusing as the law says one thing but Judges rule however they decide to.Our properties are held by Wyoming situs trusts and a WY LLC is the trustee I am manager of the LLC.  

And those are found of course by just looking at the non situs run on the county tax records.Also @Joel Owens  I don't see Joel driving around and looking to see if some 100 unit apartment he is brokering happens to be vacant...

Does anyone have any feedback on Situs Real Estate operating out of Denver, Colorado?

Even using zip code will eliminate some records as the assessors tend to have a lot of parcel with incomplete, missing, or inaccurate property (situs) addresses.

I may have a filing obligation even where there is no income tax due.Each state is given pretty broad authority in establishing their jurisdiction (nexus is just the right/jurisdiction to deprive one of property essentially).So Ohio I know is complex because I had to prepare a couple.Basically for state income tax nexus is determined by situs of real property. 

You would typically need the APN to start your search and maybe the property situs address.

You may be able to get the assessors data and then use that to determine absentee owners by comparing mailing and situs addresses, but that is far more difficult and confusing than using Listsource. 

For about $50 you can hire a programmer on Odesk.com to scour the tax records and create a list of owners who live at a different address than the situs property.