According to the documents filed in court (you can find them at The Smoking Gun), the codefendants will testify that they personally witnessed him killing the dogs.
Be careful what standard you set for “knowing” whether something occurred. From a purely scientific point of view, one cannot “prove” that Napoleon existed.
Actually it said they “collectively” participated in the death of the dogs. Rather interesting way to put it. Drowning dogs is still practiced up here in the hills. The irony is that people would be appaled if he gassed them to death and that’s how we “euthenized” them at the dog pound.
I found it interesting that the guys fought the same dogs over and over. The standard belief is that the dogs fight to the death. Usually one just gives up.
The problem is not necessarily the fighting. It’s everything before the fighting. Vick gave away a lot of dogs that did not fight. They were all over town. That’s why pit bulls are so dangerous.