So, what else do we know about this man and what's behind that manifesto? Abc's nick watt with that. Reporter:33-year-old christopher dorner lives here in orange county with his mother, a forensic... See More
So, what else do we know about this man and what's behind that manifesto? Abc's nick watt with that. Reporter:33-year-old christopher dorner lives here in orange county with his mother, a forensic psychologist who read his manifesto, has a startling conclusion. Dorner was never planning to return home. I think he wants to kill as many people as he can. Reporter: And be killed? And then be killed. Reporter: Four years ago, he says, when he was fired by the lapd, he claimed a colleague kicked a detainee. The department disagreed. Former chief bratten, who wouns bet bratten, doesn't remember the case. Believe me, the department goes through exhaustive efforts and there are multiple series of review before an officer is discharged. Reporter: No one gropes up and wants to be a cop killer, quote dorner. "It was against everything I've ever was."In his sometimes rambling 6,000-word statement, dorner says he wants to clear his name and expose corruption. He is narcissistic. He is grandiose. Reporter: That is a personality disorder. But based on this manifesto, dr. Askins does not believe dorner is insane. He knows what he's doing. Reporter: But why now? Dorner was honorably discharged from the u.S. Navy reserves just last friday after ten years service, including a tour in the persian gulf. Was that the trigger for this killing spree? Or evidence of careful planning? I have more questions than i do have answers at this point. Reporter: If corner gets his apparent wish, if he is killed, we might never know the whole truth. Nick watt, abc news, los angeles.
This transcript has been automatically generated and may not be 100% accurate.