RIVERSIDE (CBSLA) – One of two teen boys charged in the beating death of a classmate at a middle school in Moreno Valley last month made his first court appearance Wednesday.

The suspect, who was not identified because of his age, plead not guilty in Riverside Juvenile Court to one count of voluntary manslaughter.

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Landmark Middle School in Moreno Valley, Calif. September 2019. (CBS2)

On Sept. 17, cell phone video showed two boys punching the victim, 13-year-old Diego, at Landmark Middle School.

The video showed Diego being punched in the face by a boy in a black t-shirt outside the school’s main building. As he stumbles, he appears to be hit from the left by a second boy. Then, as he falls to the ground, he hits his head on a concrete pillar.

According to students who witnessed the fight, the student was foaming at the mouth and may have suffered a seizure. Witnesses said CPR was performed on him before he was rushed to a hospital in critical condition. He passed away about a week later, on Sept. 24.

The two suspects were arrested the day following the attack and booked into Riverside County Juvenile Hall. They were initially charged with assault by means of force likely to produce great bodily injury. However, on Sept. 30, the Riverside County District Attorney’s Office amended the petitions against both of them to include voluntary manslaughter.

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An undated photograph of 13-year-old Diego.

No cameras were allowed in Wednesday’s hearing. Diego’s parents were present but did not speak to reporters. The suspect’s attorney, David Wohl, told CBS2 outside the courtroom that his client was himself bullied and has demanded the Moreno Valley Unified School District turn over student records he says will prove that. Wohl blamed the district for failing to address an ongoing issue of bullying and violence at Landmark.

“A culture was developed that fighting was just part of life there,” Wohl said. “It happened all the time.”

Landmark has dealt with several incidents of violence in the past, parents told CBS2. In March, another violent attack on the campus resulted in 19 students being treated for exposure to pepper spray after campus security guards were called in to break up a fight that allegedly began after one girl attacked another girl from behind, and the fight grew into a swarm.

The suspect remains in custody. His pre-trial hearing is set for Nov. 1. The second suspect is set to be arraigned Oct. 15.

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The two boys cannot be charged as adults because they are under the age of 15.