Unless this guy completely hid his true self from his therapists they failed miserably
That's one of the hallmarks of narcissism -- patients who have it are called "therapist killers." Talking therapy was the wrong route for this kid, especially due to his photographic memory, which made it easier for him to lie and not get caught out. He needed some whole-body work, like Rolfing, kinesthetics, neurolinguistic reprogramming, and certainly the family needed therapy and instruction.
The moment the father dumped the mother for a young tart, all was lost. All extra money then went into the second family, and not into proper intervention for an already-ill child, which should certainly have included lots of family activities with Dad and son not focused on Dad's hot new sex life, nude photos of the hot new wife for sale@ $1,200 a pop on Saatchi, and making violent movies. Instead of taking the kid to church and involving him in outward-directed activities like soup kitchens, Habitat for Humanity or Peace Corps volunteering to suit their liberal agenda, they let the kid fester in violent video gaming for months at a time. If they are so opposed to guns, why did they allow him to use war video games?