The man who kills the grizzly bear illegally is and "old friend" of Walter's. His name is Rusty, and Walter calls him "the best outfitter in the San Juans...best outdoorsman you ever saw." Rusty first appears in the narrative when he comes to ask Walter's permission to hunt on his land. Cloyd takes an instant dislike to Rusty, because he gets the feeling that the man looks down upon him. His mannerisms make Cloyd feel that he thinks meeting and greeting Cloyd is "a joke" (Chapter 8). Cloyd's hatred towards Rusty is solidified when he discovers that Rusty is a bear hunter; bears are sacred to Cloyd's ancestral tribe, and not to be harmed (Chapter 9).
Rusty reappears later in the story. He and his brothers are out on a "pleasure hunt," and Cloyd, not realizing that it is open season on bears, tells Rusty about a large bear that he has seen in the vicinity (Chapter 17). Using this information, Rusty tracks the bear and kills it, but after the deed is done, he uneasily observes the unique shape of the creature's forehead and the hump on its back. The bear he has killed is a grizzly, which is an endangered species and thus protected by the law. The penalty for killing a grizzly is a "hundred thousand dollar fine and a year in jail."
Whether Rusty had been fully aware at the time he killed it that the bear was a grizzly is debatable. He says that the possibilty "crossed (his) mind," and begins to make up excuses, but in the end, he admits that he "got carried away." The hunters in his group urge him to just keep quiet about the incident, but Rusty knows that the carcass of the bear will inevitably be found. According to the law, "if a grizzly's found dead, you're supposed to report it...so the Department of Wildlife's scientific guys can study it." Rusty believes that the best way to handle the situation is to turn himself in. The game warden is Rusty's friend, and he is hoping that he will be lenient in dealing with him (Chapter 19).