Crazy Neighbor

Location: Oregon. Hi, I live in Oregon, as does my brother, let's call him Barry (age 27). I was walking my dog around his apartment complex when a neighbor, Mary (~age 35), asked to pet my dog. I said yes, had some small talk, and when my dog wanted to Barry's door, I said "Hey let's not bother Barry". Mary got a weird, almost crazy look in her eyes as she widened them, saying "Oh no, Barry deserves it. He's a pedophile, didn't you know? He exposes himself to kids. He's an animal abuser, too, there's maggots in his cats shit. He's even a squatter, he's been living there without paying rent for months!" which conveniently not mentioning the fact he's got a roommate that refuses to pay any bills.

I looked at her and kept my expression neutral, since I've been helping him with rent since he lost his job, and nowhere is hiring anymore (small town), I've helped his cat's ear infection and never heard of these maggots, and this is the first time I've heard of this pedo shit, but I find it convenient it's come up around the time he's had younger family visiting.

I asked him what the hell was up over a messaging app, and apparently this neighbor has been throwing things at his door, egging his porch, trying to push her way into his house, and going around telling everyone else here that he's some pedo.

That's unfortunately just backstory, as our problem is this. I bought him a ring doorbell camera, so he can get footage of getting harassed, for the police or some protective order, or something. I set it next to his other doorbell, which faces Mary's door, in an open hallway next to the parking lot. Now, every time Mary passes the doorbell, she flips it off, constantly rambles about Barry being a pedo, rants about "Barry just got fucked" like Mary reported something somewhere, but the problem here is that every few hours, she's now covering up the camera, with tape, papers, or sheets. She's now claiming the camera is set up to spy on her child, through Mary's front door. The door is solid with no windows, and there's no windows next to the door at all.

He can't afford a lawyer, and the cops don't seem to care too much. But this shit is constant. Every day, these lies and rumors, ever few hours new covering over the door bell. This shit can't be legal right? What do we even do?