what does Steve learn about making poor choices?

Is Steve Harmon guilty of the crime? Did he participate in the robbery, serving as a lookout man to check if the drugstore was clear? Sometimes Steve gives hints that he might have participated, such as when he writes on page 140, "What did I do? I walked into a drugstore to look for some mints, and then I walked out. I didn't kill Mr. Nesbitt." In Steve's mind, he might be forgiving himself, but in the law's view, if he participated in the robbery, he is as guilty as the person who shot and killed Mr. Nesbitt. This might be too harsh of a law, but it is the law. I think Steve's choices really relate to the company he kept and his motivations.