New video of a fatal stabbing at the Urban Assembly School for Wildlife Conservation could be a critical piece of evidence.

The attorney for 18-year-old Abel Cedeno believes the video will prove his client's innocence.

As News 12 has reported, Cedeno was charged in the stabbing death of 15-year-old Matthew McCree.

The video shows a student in a white shirt in an altercation with Cedeno. His attorney, Robert Feldman, says the boy is McCree.

"Abel was being attacked by McCree and (Ariane) Laboy, and because he was being attacked, he can defend himself," Feldman says.

Cedeno then appears to stab McCree. Police say he also critically injured Laboy.

McCree's family lawyers downplayed the video's importance. 

"A grand jury indicted Abel Cedeno for manslaughter based on evidence which most likely included this video in its entirety," they said in a statement. "No conclusions can be drawn showing a part of it out of context."

But Feldman says the Bronx district attorney gave him the video last Thursday, more than a month after he says he believes the DA came in possession of the evidence.