Sitting unshackled, the now 12-year-old boy listened as Chief Deputy Dist. Atty. Michael Soccio told a Riverside County judge that the sandy-haired boy knew that killing his father, Jeffrey Hall, 32, was wrong.
The boy "is no different than any other murderer," Soccio said in his opening statement.
He "would have shot his father if he was a member of the Peace and Freedom Party."
But Public Defender Matthew Hardy said the boy, who had learning disabilities, pulled the trigger after being manipulated to kill Hall by his stepmother, Krista F. McCary.
Hardy portrayed her as angry over the possibility her husband was about to leave her for another woman.
"We are not going to suggest she killed him," Hardy told the judge. "She used this young man to kill him."
The boy, whose name is not being released because he is a juvenile, has been charged with murder.
If the allegations against the boy are found to be true, he could remain in juvenile custody until he is 23.
During his opening statement, Soccio portrayed the family as rather normal, showing the court several photos, including one of the family frolicking in the surf.
Soccio said the boy shot his father with a .357 magnum revolver because he believed Hall was about to leave McCary and take custody of the boy. So, Soccio said, he "found a way to stop it."
While on a backyard swing set the day before, the defendant told one of his sisters about the plan, Soccio said.
Superior Court Judge Jean P. Leonard, who is acting as a juvenile judge in the case, must rule that the child knew that his actions were wrong at the time of the shooting to find the murder allegations true.
Hardy argued that the child's sense of right and wrong was clouded by the household in which he lived, where National Socialist Movement meetings took place, guns were accessible and beatings were regular. The upbringing conditioned the boy to violence, he said.
In the end, Hardy argued, the child believed that he was protecting his family and putting an end to the violence Hall inflicted upon them. The boy thought he would become a "hero," Hardy said.
"He would not have pulled the trigger if he thought it was wrong," Hardy said.
Riverside Police Officer Michael Foster, a prosecution witness, testified that the child expressed remorse on the day of the shooting.
"He asked me things like 'Do people get more than one [life]?' " he told the court.