The judge backed prosecutors -- claiming they proved their case that the then 13-year old suspect is guilty of second degree murder for the Valentines day attack on 15-year-old David Gutierrez.
The judge also sustained robbery and assault charges.
MORE: 'At a complete loss': Family members react to killing of 15-year-old at Santana Row in San Jose
Family members react to killing of 15-year-old at SJ Santana Row
Family members and Santa Clara County DA Jeff Rosen applauded the ruling and are pushing for the longest possible sentence.
"When a minor's actions demonstrate such extreme violence, then we must protect our community," Rosen said.
"We don't think that the 13-year-old should be serving 6 to 8 months in an open ranch, that's not rehabilitation for an evil, violent person that he is," the victim's aunt, Diana Gutierrez, said.
The defendant will be back in court in July to face possible additional charges, and sentencing will follow.
Police claimed that Gutierrez was attacked because he was wearing red. They found he had no gang connections.
The defendant's attorney says the stabbing was an act of self-defense following a series of violent encounters.