Unfortunately without something in writing, sale contract, lease agreement, exchange agreement, etc.
It turns into a he said/she said.
Without something in writing, a gentlemans agreement usually ends up in court or close to it, depending on the people involved.
Most likely nothing will develope further due to the distance-3 hours.
But, certainly use this as a lesson learned and do paperwork, lots of it, even to friends/relatives.
And don't give them the previous owners info, they have nothing to do with it and don't need to be dragged in the middle.