This man is being very unreasonable. See what you can do to get him to take his sign down and camera. Call the Police and the City. You should not have to live like you did something wrong.
I have a cat that never ever goes outside. I love him too much to have something happen to him. I have only had Dukie for 1 year. Never had cats before, only dogs.
I have had strays use my yard for a litter box. My family and friends have had the same and it always under the living room windows. Why??? I have used moth balls, but they stink up the front porch. I changed 2 years ago to Cayenne Pepper, I have to put it on several times a year. No more cats using my front yard for their litter box. Good Luck!!! HUGS to you.