Erickson was 18 at the time and could face life in prison without parole if he is convicted.
Chief Deputy District Attorney George Brauchler argued that Erickson agreed to participate in the attack as long as it looked like he was pressured into it and or could emerge as a hero by killing McKinney.
Brauchler said the students' concocted “victim-hero” strategy unraveled after Castillo rushed Erickson when he pulled out a gun inside a darkened classroom as students watched a movie. Erickson’s gun went off, Castillo was killed and others tackled him, he said.
Their other possible scenario, in which McKinney killed himself, was stymied after an armed security guard apprehended him, Brauchler said.
Erickson’s lawyer, Julia Stancil, said her client was manipulated into joining the attack by McKinney, a new friend who preyed on him during a family crisis.