The mom of the 13-year-old victim does not want to use her full name.
"Sylvia" wants justice for her son. She says the video takes her breath away.
Two weeks ago, her son was riding Walla Walla's public transportation system, Valley Transit, on his way home from school.
Video obtained from security cameras on the bus show two angles of the boy being attacked. Sylvia says the assault was unprovoked and happened not once, but twice.
Sylvia says it all started when the man commented on her son's iPod. "He says, 'that is an awesome game,' and that's when this individual turns around and knocks the iPod out of my son's hand."
She says he slapped him once, and then again. It was the start of the altercation between a seventh-grader and Robert Kreykenbohm, 30, but not the end.
The video shows Sylvia's son and his friend get up and move away from Kreykenbohm, placing a row between them. Kreykenbohm says something to the boys. It's not clear exactly what.
"My son goes 'what what,' and you can hear the words 'what what,' and my son goes, 'I can't hear you,'" explained Sylvia.
The video shows how Kreykenbohm leaps from his seat and unleashes five blows to the boy's head. The Walla Walla Union-Bulletin says the suspect is six feet and 200 pounds - no match for a seventh-grader.
"I was crying. I walked away from it. I was throwing up, that's how sick it makes me," recalls Sylvia.
A man sitting near the front of the bus tells Kreykenbohm to leave. He does, but the bus keeps going.
"And continues driving like nothing happened. Who does that?" asked Sylvia.
Moments after Kreykenbohm gets off, Sylvia's son breaks down.
"He is traumatized for life," she says. "He's not the same boy that he used to be. He comes home and buries himself in his bedroom, and he doesn't want to come out."
Kreykenbohm was later arrested for assault, but he's back out of jail, released on his own recognizance. For Sylvia, that's terrifying.
"I want him to go to jail for a while. He needs to pay for what he has done to my son."
While he's allowed to walk the streets, Kreykenbohm is not allowed to ride a bus.
Because we got the security video after hours, KEPR was unable to contact Valley Transit ourselves, but the agency spoke to the Walla Walla Union-Bulletin and called the assault an "unusual situation."
Valley Transit's general manager told the paper the driver did not see the assault since the teen didn't make any noise during the attack, and a fellow passenger obstructed the driver's view. Police weren't called until the boy arrived home.