Steven, I understand your argument regarding involving the cat owner. Honestly, I don’t know anyone who wouldn’t be immediately willing to solve the problem with you if it was proven to be their pet. There are always a few ignorants everywhere. However, where I have to vehemently disagree with you is your last conclusion to kill the cat if necessary. YOU MAY NOT do that and you do not have the right to do so. If the cat owner finds out, harsh penalties will be imposed. That you feel it is your personal right is a completely different matter. But that does not make it legal. So you are forced to resolve it differently.
By the way, you have to be very careful in choosing your methods. Live traps are not for free use. Even in our animal welfare organization, there were cases where we accidentally caught a cat with an owner (a classic outdoor cat). The cat was cared for, registered with Tasso, and kept in the animal shelter. However, the owner caused a huge fuss to find her pet. Apparently, that was not quite cheap. The association had to reimburse the woman for the costs. We should not have caught the cat. It did not matter that we did not do it intentionally.
Even spreading pepper in the garden is very borderline. If the cat gets irritated, you may have to pay for veterinary costs.
Regarding the feces, courts decide very differently. Ultimately, they seem to agree that you have to tolerate up to 2 cats on your property as visitors. Whether the deposited feces are to be accepted as a reasonable restriction of your ownership is seen very differently.
If the cat deposits the sausage in the flowerbeds, neatly buried, probably every court will laugh at you. In the case of andimann, it might look a bit different, since the kitty deposits it so conspicuously. But how it will be decided we will only see when it comes to a case.
Contrary to some indications, there is NO uniform jurisdiction to which one can refer.