Noah Rentas, 18, the teen who fatally stabbed Michael Hernandez, 27, outside Brooklyn’s Barclays Center last week, was believed to be robbing the victim as part of a citywide gang of

As police escorted the teen from the precinct to Central Booking, Hernandez’s mother and three female relatives repeatedly cried out, “Coward!” while the grieving mom clutched a framed photo of her son close to her chest. Rentas’ arraignment in Brooklyn Criminal Court was pending Tuesday night.