Rudy:

While I can understand how you could be offended by what you saw, problems like this are best handled with kidd gloves.

After all, if you come off as demanding that something be done, you're going to force your neighbor into a defensive position, and he's gonna say "Look Pal, it happened in my bushes on my property. It doesn't affect you, so mind your own business."

That's why I think that if you go to the neighbor or landscaping crew bearing gifts (like a camping toilet), things will start off in a spirit of co-operation.