Chris Aguilar, 16, spoke little during his initial court appearance in Phoenix, while loved ones of Michael Montoya, 16, broke down into sobs.

Maryvale High School was one of two Phoenix Union High School District schools to pilot an advanced weapons detection system.

Chris Aguilar, 16, is accused of fatally stabbing Michael Montoya, 16, at Maryvale High School on Aug. 19. A knife was recovered, police said.