Countrymouse
Country exile in the city
With the neighbor concentrating to hard on you guys with the cameras all pointed at your house, I have to wonder if the guy is a voyeur.
Also, the next time he tries to threaten you even via the RING device, make sure you take a vid of the direction it's coming from, even if there is no action there, you will have his voice on the vid. And keep doing this.
And go to your local PD and just have a talk with a supervisor just telling him/her that you have some very strong concerns as to the mental state of (neighbor's name) and then let them hear all the ranting and raving from the vid you recorded them on and tell them that you just wanted to let them know what has been going on and that the neighbor does not seem mentally stable.
That way, you've planted a 'seed' in their minds about the neighbor and even though they don't right down a report, the neighbor will be now considered maybe a bit of a threat to police.
Remember, the first one who calls/approaches a situation with the police is always believed and also, research has shown that people always believe the first thing they hear about someone, even if they've never met them.
It's all just human nature, so you have to start being proactive like Right Now, to establish yourselves as being the sane ones, if that nutball next door decides to make a false accusation on you and calls the cops.
I'm only saying all this, because I've seen your scenario play out before and I was lucky to stand on the sidelines, observe and learn what to do with a person like the guy next door. V
THIS. That is the first thing I thought of. YOU be the first to go to the police---even better if you go to the local PD and have a talk with not just an officer but an upper-echelon (sergeant or chief) person, quietly and rationally, describing your concerns and (even) asking their advice as how to best handle this.
EMPHASIZE how you USED to be on good terms with this neighbor and don't understand the sudden change.
ASK them to record your concerns in a report, as well as for their advice.
Tell them you fear not only his calling the police, but whether he might PERSONALLY try to retaliate against you (you're painting him as unstable and paranoid is the point)