NEW YORK (CBSNewYork) — A teenager accused of stabbing two fellow students, one fatally, at a Bronx school again waived a court appearance Tuesday.

Abel Cedeno, 18, faces murder, attempted murder, manslaughter, attempted manslaughter, assault and criminal possession of a weapon charges.

READ MORE: NYPD: 4 Suspects In Custody After 3 Subway Riders Slashed Within Minutes In Lower Manhattan

Police said Cedeno stabbed and killed 15-year-old Matthew McCree and critically wounded 16-year-old Ariane Laboy at the Urban Assembly School for Wildlife Conservation on Sept. 27.

Outside the courthouse, supporters of the alleged killer rallied behind the family as the victim’s supporters shouted “Justice for Matthew.”

Cedeno’s sister, Vanessa, said her brother was the victim of relentless bullying that she claims the school did nothing about.

“He spoke to two teachers and they told him to ignore it and be the better person, basically to suck it up,” she said.

Cedeno’s attorney, Robert Feldman said the teen was acting in self defense and under extreme emotional distress, WCBS Newsradio 880’s Marla Diamond reported.

“He snapped. He lost it. He was not in his right mind as a result of being tortured,” Feldman said.

READ MORE: Change In Stadium Seating Policies Leaves Yankees Fan In The Lurch: 'It's So Last Minute, I Can't Meet Their Requirements'

Cedeno waived his initial court appearance earlier this month.

His attorney Debra Rush said Cedeno will testify before a grand jury.

Dozens of mourners turned out at McCree’s funeral Saturday.

Police said Cedeno admitted to buying the knife online after weeks of being bullied at school, but said neither teen who was stabbed had any prior issues with Cedeno.

“First time these kids bothered him by throwing pencils at him. He bought the knife two weeks ago just to have a knife. Other students harassed him verbally in the past,” NYPD Commissioner James O’Neill said.

The Legal Aid Society is representing Cedeno. In a statement they said it was “reviewing the facts and circumstances of this case including the long history of bullying and intimidation Abel has endured.”

McCree’s mother, Luna Dennis, said her son was not a bully.

“My son, again, was never a bully. My son never had words with this boy, the accused killer, before he took my son’s life,” Dennis said.

MORE NEWS: Questions Linger After Death Of 12-Year-Old Romy Vilsaint: Family Says He Was Bullied At School But 'Nobody Is Telling Us Anything'

Metal detectors have since been installed at the school.