Did I miss something? What was the motive for the murder?
Because the instructor wouldn't let him be a firefighter? It's hard to believe a guy who wanted to be a firefighter because he respected his father so much would kill another respected firefighter because he wanted to fire him for perfectly valid reasons.
I thought he might be blaming the instructor for his father's death but I don't see anything that connects him to it, he's not even mentioned in that story.
