I wonder why someone would do that. I mean it's very likely it ran away and got attracted by all the dogs so it came into the park. Or maybe someone anadoned it. But that would be very odd. I mean the dog is a purebred puppy. And sometimes those can be quite expensive. Maybe he was abandoned. I hope he gets adopted into a good home or finds his owner. You did a good thing and good luck with your search for the owner.