The defence says Thomas Gilbert Jr.'s mental illness should absolve him of responsibility in the murder. Prosecutors argue his insanity claim is a ruse.

Years before Thomas Gilbert Jr. was accused of shooting his father in the head, he told a psychiatrist that he dreamed about kicking his father and screaming, "Stop it! Stop it!"

Even though his father had supported his lavish lifestyle — rent, overseas trips and a US$1,000 (NZ$1,500) weekly allowance — Gilbert continued to have angry delusions about his father, according to psychiatrists who treated him in the past.

Their assessments came during the fourth week