Jeff Hall, a leader of the National Socialist Movement, was shot while he slept on the couch in his Riverside home in May 2011. Police and prosecutors say the gunman was Hall's then 10-year-old son, who they said had already shown signs of violent behavior.
Anna Salter, a psychologist called by the prosecution, said the boy plotted the event prior to doing it, but that the previous violent outbursts weren't premeditated.
"[The boy] has had a tragic history and upbringing, but it's not a hopeless case," Salter said. "It's possible he could have a future without violence if given treatment."
She said the father's life as a neo-Nazi had nothing to do with the boy's actions.
The boy's attorney initially entered a plea of not guilty by reason of insanity, but has since withdrawn the plea, The (Riverside) Press-Enterprise said Tuesday.
The boy's homicide trial is taking place in juvenile court and a judge alone, not a jury, will render a verdict. If convicted, the boy could be held in a juvenile detention facility until he's 23 years old.