An abused 12-year-old boy who shot his Neo-Nazi father dead while he was sleeping at their California home was found guilty Monday of second degree murder.

Joseph Hall was 10 at the time of the killing, in which he shot his 32-year-old father Jeff Hall in the head in the early hours of May 1, 2011, as he slept, drunk, on a sofa. He used his father's .357 revolver.

"The minor knew what he did was wrong," said judge Jean Leonard of the Riverside County Superior Court, east of Los Angeles, adding that Hall planned the attack after his father threatened to break up his marriage and abandon the family.

"He put the barrel of a handgun to his father's head and pulled the trigger. There was planning and understanding in the commission of this crime," added the judge, who handed down the conviction without a jury.

The judge explained how, for two year's before his death, the boy's father exposed his son to extremism through his National Socialist Movement activities and resorted to "out-of-control methods of punishment" when the boy misbehaved.

But he said this did not mitigate the crime, and noted that the boy had long had violence tendencies.

"The court recognizes this was an isolated minor who knew more than the average child about hate, guns and violence.... From the age of 18 months, he exhibited violent behavior," said Leonard.

"He was expelled from eight schools. But he was not a naive little boy unaware of the ways of the world," he added.

Sentencing will be decided at a later date.

The ruling comes amid intense debate about gun crime and gun control in America, re-ignited by last month's school massacre in Newtown, Connecticut which left 26 people dead including 20 young children.

[Gavel via Shutterstock]