Mr. Brooks: Before I was the Thumb Print Killer, I killed a lot of people, in a lot of different ways.
Mr. Smith: If you're planning on doing anything...
Mr. Brooks: We're both aware of the rules Mr. Smith, but I feel I must warn you that if you enjoy killing, it can become very addictive; it can ruin your life.
Mr. Brooks: If I were here to kill you, you would already be dead. Today I realised our conversation was a little one sided, so tomorrow night, would you be so kind as to bring all the photographs and the memory card from your camera? That way we can like each other simply for who we are.
Chosen answer: It sounds like Dissociative Identity Disorder. And I think compulsive killing is something he chooses to do, and not connected to his DID; and from skimming the article, it doesn't appear to be genetic.
Cubs Fan ★