The 16-year-old boy allegedly placed a drawing addressed to a teacher in their filing cabinet that depicted a character holding a bloody knife with blood seeping out of classrooms with the caption "school stabber at Glenbard East 120 dead," according to the DuPage County State's Attorney's Office.
He was taken into custody Wednesday and charged with disorderly conduct - threat to a school, a Class 4 felony.
"Any threat to the well-being of our students, teachers and school personnel will be taken very seriously," DuPage County State's Attorney Robert B. Berlin said in a statement. "Students have got to understand that school threats are no joking matter and can have a chilling effect not just on students, teachers and staff, but also on parents, siblings and the entire community."
The student was released to the custody of his mother where he is on home detention lockdown, officials said.
His next court appearance is scheduled for May 5.