James Bing broke down on the stand when talking about abuse he says McInerney suffered.
According to Bing, violence and drugs were the norm while they were growing up in the McInerney household.
Brandon McInerney's older half-brother James Bing, 24, wept as he recounted how he was told by his late stepfather, William McInerney, that Brandon was molested by a male cousin when he was a young boy.
Bing was told this shortly after Brandon was arrested for shooting and killing fellow classmate Lawrence King.
"When he told me about this -- this was after the shooting -- about it, and I was told by my mother and other family members about it when I was much younger," said Bing. "They tried to hide it from me because they know how I'd react. Like, I love my brother very much and hearing something like that, you know, I might have done something stupid. I might have beat the [expletive] out of that kid, you know, it's my little brother. So it was hidden from me. I knew something went down because they said something happened between Kyle and Brandon, and after that, Kyle's gone."
Bing spent the entire morning on the stand. He denied he and McInerney had any white-supremacist views or were members of any gang.
Brandon McInerney, 17, is accused of shooting Lawrence King twice in the head during their computer class at E.O. Green Junior High School in Oxnard in February 2008. Brandon was 14, King was 15.
The prosecution says McInerney killed King because he was gay.
Defense witnesses testified Wednesday that King was needy and disruptive in school.
A former teacher testified Wednesday that King would follow boys into the bathroom to watch them squirm, and added that King would blow kisses at male students and say "I know you want me."
Another defense witness, a cafeteria worker at the school, also took the stand Wednesday to testify she had concern for King because of the high-heeled boots he was wearing to school days before the shooting.
"And in the quad we have wood in between each of the squares, and the wood was already rotting, and I was just thinking he was going to put one of those heels in there and twist his ankle or break his leg," said Hilda Valenzuela.
If convicted on the murder charge with the hate-crime enhancement, McInerney cold sentenced up to life in prison.
If convicted of a murder charge with a hate-crime enhancement, McInerney faces 53 years to life in prison.