Who knows, the dog owners that go to that park may be lazy and just leave their dogs' huge piles. I can understand how that would piss off a long time resident who is sick of stepping in sh*t. Maybe the person is visually challenged and when gets home, perhaps doesn't take shoes off, and has had to deal with sh*t all over her carpet.
Of course what was done is horrible, but the media as usual only has a part of the story.
Dog owners letting their dogs off leash should take a couple of balls with them, to keep their dogs' attention! Was it an off leash park? If not, that might piss a long term resident off, that people are letting their dogs run wild and pooping all over.
I'd be pissed if my dog was poisoned. The dog owner has my empathetic rage.