What is the message?

The film is about scapegoating more than anything. A young girl is dead and it's next to impossible to discern who did it, so the community's collective pain is hurled at the four who trivialized her death in order to preserve their holiday. Also, the film obviously compares the men's cavalier disregard with the heartless indifference of the killer himself. Which isn't to say they're as bad as the murderer, not at all, but they do share one of the traits that enables him to do what he does.