The teen accused of stabbing two alleged bullies at school, killing one and injuring the other, pleaded not guilty in court Wednesday.

Abel Cedeno, 18, faces manslaughter and assault charges in the stabbing that killed 15-year-old Matthew McCree and critically injured another student at the Urban Assembly School for Wildlife Conservation. 

Cedeno says he was the victim of relentless bullying over his sexual orientation. His defense lawyer says two teachers stood by and watched him being harassed just before the deadly encounter.

"They should have been stopping this," he says. "They are the only adults in the room."

Relatives of the victims stood outside the Bronx Hall of Justice Wednesday carrying signs that read "Justice for Matthew."

"Cedeno's parents can go visit him on his birthday," said Luz Hernandez, whose son would have turned 16 next month. "Do you know where I have to go to see my son? To the cemetery."

Both victims' families have filed a notice of claim against the city Department of Education and the NYPD.

The DOE did not immediately respond to a News 12 request for comment.

Cedeno is expected to be back in court on Nov. 29.