The prosecution's case was based on the belief that Presa Canario dogs are dangerous by breed, Knoller and Noel knew that these particular dogs had bitten people and animals and therefore were dangerous to humans, neither Noel nor Knoller took sufficient precautions to protect people like Whipple, and Knoller herself knew that she could not control these dogs because at least one witness, Neil Bardack (see above), testified that he saw one of these dogs dragging Knoller down the street one day. 

A number of witnesses testified that the dogs previously attacked them or exhibited extreme agression against them (short of physical attack, but clearly suggestive that it would someday turn into physical attack). Given the association between these defendants and the prisoners, Noel and Knoller certainly were aware that the Presa Canario breed was designed for violence. A veterinarian sent the defendants a written warning that the dogs would be "a liability." One of the dogs even bit Whipple prior to the day it killed her. 

The defendants were charged under three laws:

  • The mischievous animal law (Cal. Penal Code sec. 399). This law says, essentially, that the owner of a dangerous dog that kills a person is guilty of a felony if the owner's criminal negligence permitted the dog to do so. Both Noel and Knoller were charged with this crime.

  • Involuntary manslaughter (Cal. Penal Code sec. 192(b)). This law applies to any person who kills another as a result of doing something lawful "which might produce death ... without due caution and circumspection." In other words, this is a homicide that results from criminal negligence. Both Noel and Knoller faced this charge.

  • Second degree murder (Cal. Penal Code secs. 187 - 189). The distinction between involuntary murder and second degree murder is that this crime is a killing with malice, as opposed to criminal negligence. Only Knoller faced the second degree murder charge.