Cat Piss.
All animals have a purpose and a way of life. Some good and some bad, if you allow it to happen. Most kill because they are hungry, don't we? I have over 35 pineapple plants that animals eat the pineapples before they are ripen. My solution to this problem was not to kill them, but deter them. I made a circular wire screen, that will fit over the pineapples to protect them until harvest. Had problem with rabbits and place cayenne pepper powder at their entry into my fenced yard. May also work on cats. Maybe rats are there also and that is why you have cats. Once an animal feels comfortable defecating at a location they will go there again. When I see a spot of use, I again pour a little cayenne power at the spot, problem solved. Let your neighbor deal with the problem. LOL