but what about .... ?

Your plot explanation does do a pretty good job about explaining what's really going on in the movie and how it ends the way it does, but ya hafta think 'why?' Why was the little boy the killer? The key is at the end when he tells the sole surviving character, a hooker, that whores don't get a second chance before he kills her. There was some mention that the boy's father had left, with some awkward tension at the mention of this by the step-father. Methinks the boy's mother cheated on the father, thus the father leaves. The boy acts out in rage at the mother for making the father leave. After all, who is the first person the boy tries to kill in the movie. The mother. He coaxes her to the car window where she is then hit by the limo. Plus the Motel Clerk personality is verbosely anti-whore in sentiment, and as another one of Malcolm's personality, threatenned the life of the hooker, Paris. So I'm thinking the boy personality is maybe Malcolm's repressed childhood of when his mother cheated on his father that took him over (whereas the John Cusack personality was originally closest to his actual personality) and killed the people that were actually murdered who Malcolm is on trial for killing. What I'd like to go back and see is WHO those people are that Malcolm killed? Did those murders take place in a motel? Was one of them his mother? I dunno. I feel like those are either loose ends, or something I didnt pick up on in the plot. What do you think?