finding owners

I am trying to finding an owner of vacant property in foreclosure. It has equity and worth pursuing. Can’t find the owner. Actually the owner has Alzheimer’s and the son is POA. Can’t find the son either. I believe the POA has an unlisted number. I’ve sent letters and flyers, and even address correction request, but no reply.
Any suggestions for success. Time is running out to do a pre-foreclosure sale if I can’t find the POA.
Max

If you’re local, try knocking on the door of the son with the POA.

If not local, and no response to your letters, I’m sorry…

Good Luck!