Had a version of this happen when I was a kid and we finally moved in to our own home. It needed a ton of work and we were burning construction wood scraps in the backyard and our new neighbor came up and said we were burning on his land. He even had this plot of survey thing that showed our property relative to his property. It looked like this -
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He thought we owned nothing but our deed said one acre. He basically spent a whole summer trying bullshit down at the courthouse, the police station, etc. The cops showed up over I think no building permit? It took a bit but the cops figured out he was the crackpot and things started to calm down. He was peeking in our windows when we weren't home. Before we moved in he and another neighbor kicked a fucking hole in the foundation that we had to repair. Found that out quite a few years later.
Video!