Swiss law states that "pain, damage or suffering must not be unjustifiably inflicted on an animal, nor must any animal be subjected to severe anxiety."
In defense, the zoo explained that it had kept the bears together to replicate a "natural environment", which Nünlist contests. Male bears are solitary animals in the wild and do not typically remain with their offspring, he says, making the father's violence towards his cubs "predictable".
"The fact he killed the cub was in his genes, he did it because he wanted to mate with the female again," says Nünlist. "The female didn't put up a fight because if she had, the male would have killed her too."
If investigators determine that the zoo's neglect constitutes animal cruelty, it would likely result in little more than a fine -- but for Nünlist, the legal action is more about raising awareness of how animals are treated in captivity.