Still not worth paying for unless they are researching and determining if the deceased owned property.

Since you mentioned you are cross checking the appraisal district to see if the deceased had any real property, thats a good first step, 2.

Probate is a legal process to disburse a deceased person's assets.  

Is the borrower deceased?

If deceased owners get you excited, you'll find them by looking for reverse mortgages in default.

Current property owner has not been successful in locating heirs, and executer of the estate is also deceased.

Without crossing into other towns or other borders in which the market is drastically different.

Example: I just optioned from a local church who inherited it from a deceased congregation member an old grocery store sitting in a mainly residential area that the city allowed me to re-zone as residential units.

The perimeter of the city proper is bordered by a very large number of politically separate boroughs and townships.

I have a few doors myself in SoCal and recently jumped across the border to develop in Tijuana, Baja, MX when cap rates squeezed to 3 in San Diego (they're finally increasing now, unfortunately due to interest rates).