When I've exhausted phone, text, and email options I like to visit the property and scope out the neighborhood for additional options to open a conversation with the property owners/heirs.
I left a note at the door of a subject property and as I'm walking down the driveway the firetruck rolls up. We gave each other a nod and look of confusion. Thanks to the paramedics, I was able to hang around and get the homeowner to have a conversation, but she's not ready to make a deal.