Dissociative Identity Disorder -- Primal Fear, ft. Edward Norton and Richard Gere
Edward Norton has been arrested for murdering a Catholic priest, apparently in retaliation for childhood sexual abuse. Richard Gere is his lawyer.
The film is well worth watching in its entirety.
The film seems to be inspired, in part, by the case of Kenneth Bianchi (one of the Hillside Stranglers):
While he was in prison, Bianchi's attorney brought in a psychiatrist, Dr. John Watkins, to examine him. Watkins put Bianchi under hypnosis, got him to admit to several of the murders and to implicate his cousin, and then declared he had multiple personality disorder. He had killed as "Steve Walker" and thus was not competent to stand trial. Three more experts were convinced by his condition as well.
This only annoyed the investigators. The prosecution decided to bring in its own expert, Dr. Martin Orne. Detectives had discovered "Steve Walker" was the name of a college student from whom Bianchi had stolen transcripts to set up his fake psychiatric practice, which suggested he knew enough about psychology to fake a personality disorder.
Dr. Orne used a ploy: He suggested to Bianchi that most multiples have more than two personalities, and it wasn't long before Billy emerged. Bianchi also pretended to touch someone who was not there. Hallucinating is not a symptom of MPD, and they knew then Bianchi was faking it. Under pressure he admitted to the deception.