Reaume never testified. The prosecution said it couldn't find him.
But Reaume did speak to "20/20" after a private investigator hired by Brandon's defense team tracked him down.
Reaume flatly denied advocating violence or teaching any of his racist beliefs to Brandon. Reaume said that, three days before the shooting, Brandon came to his door looking for his brother, James.
"He showed up at the door, crying," Reaume said. "He's definitely troubled by something on with his life. I told him to be a good kid, sleep on the couch, my wife gave him a pillow and blanket, and when we woke up in the morning he was gone."
"20/20" also learned that "S.S.L." was apparently short for "Silver Strand Locals" -- a name for residents of Silver Strand, a mile-long strip of beach on the edge of Oxnard that lies between two rock jetties.
Silver Strand residents who spoke to "20/20" said the area is not a hotbed for neo-Nazi activity. Friends, meanwhile, said Brandon didn't have white supremacist sympathies.
"He ain't no racist, he ain't no skinhead -- nothing like that," said friend Darren Larkin, who is part black.
Brandon, he said, is "a solid cat from the beach."
As for that copy of Hitler's "Mein Kampf" -- teacher Dawn Boldrin said that Brandon had checked it out from the school library for a report he chose to do on Adolph Hitler for a World War II research project.
Jurors in the case didn't buy the prosecution's claims that Brandon was influenced by the white supremacy movement. Several jurors later told "20/20" that none of the 12 believed Brandon was guilty of a hate crime.
But after the 17 days of deliberations, jurors couldn't reach consensus on what Brandon was actually guilty of. Five jurors believed that Brandon was guilty of murder while seven voted to convict him of voluntary manslaughter.
The trial ended with a hung jury last month.
The Ventura County District Attorney's Office announced Tuesday that they would retry Brandon on the charge of first-degree murder but would drop the hate crime charge.
Brandon, now 17, will be tried as an adult, as he was in his first trial, despite his lawyer's arguments that juvenile court would be a better fit for the case.
Brandon's family worries that the teen could face life in prison -- a punishment Brandon's half brother says he doesn't deserve.
"What he did is horribly wrong. No one's doubting that," James Bing told "20/20" "But ... from the rest of your life, to rot in a jail?
"In our entire lives we're taught two wrongs don't make a right," he said, "so how does a life for a life make a right?"
Watch the full story on "20/20" Friday at 10 p.m.