In Chapter Six, Dr. Dressler is shocked that Smoke is considered a suspect in the wildfire. In what way does his shock support one of the novel's main themes?

In Chapter Six, Dr. Dressler’s shock at finding out that Smoke is a suspect shows that it is only the knowledge of Smoke’s past that makes people think that he set the wildfire. He didn't know about Smoke’s past until the police told him about it, so it never occurs to him that Smoke is a suspect.