The heartbroken mother of slain Bronx teen Lesandro “Junior” Guzman-Feliz shouted “Killer!” in Spanish at the man who delivered the fatal blow to her son — as he professed his innocence in Bronx court Wednesday.

“Assasino!” Leandra Feliz yelled at reputed Trinitarios gangbangers Jonaiki Martinez-Estrella and Danel Fernandez as they walked out of Bronx Criminal Court.

The two had just entered not guilty pleas in the brutal, caught-on-camera knifing death of innocent Guzman-Feliz, an aspiring NYPD detective who was mistaken for another person in the gang hit.

Martinez-Estrella delivered the blow that killed the 15-year-old — dragging a blade across Guzman-Feliz’s neck in the final moments of the June 20 melee, investigators have said.

Martinez-Estrella and Fernandez were among 12 expected to be indicted on grand jury charges Wednesday.

Eleven of the accused previously pleaded not guilty to murder charges when arraigned on criminal complaints.

A 12th suspect, Luis Cabrarasantos, was recently arrested in Connecticut and extradited to New York. He pleaded not guilty to murder charges Wednesday, and a judge ordered him remanded.

They are due back in court Oct. 25.