In San Francisco, Diane Whipple was attacked and killed by two dogs, Presa Canarios, which belonged to her neighbors Marjorie Knoller and Robert Noel. The brutal incident occurred in the hallway of her apartment building as Whipple tried to enter her home. Despite her attempts to fend off the dogs, she suffered fatal injuries. The incident raised public safety concerns and prompted debate about the responsibilities of dog owners, particularly regarding breeds perceived as dangerous.

The case quickly escalated into a highly publicized trial focusing on the culpability of Knoller and Noel. Prosecutors argued that the couple had demonstrated negligence and disregard for the safety of others by owning and improperly controlling the aggressive dogs. The court proceedings involved discussions around implied malice, which refers to a person's conscious disregard for human life. Ultimately, the legal ramifications of the incident resulted in a significant court ruling establishing clearer understandings of implied malice murder.

This ruling had far-reaching effects on animal ownership laws and ignited discussions on public safety measures concerning dangerous breeds. The narrative of Diane Whipple's tragedy underscored the potential hazards of irresponsible pet ownership and contributed to ongoing legislative considerations regarding animal control in urban settings.