COLUMBUS, Ohio (AP) — A teenage boy who authorities say plotted a mass shooting at a suburban Columbus high school has been indicted as an adult on conspiracy to commit murder charge.

A Franklin County grand jury handed up the indictment against 17-year-old John Staley III on Thursday in Columbus.

Franklin County Prosecutor Ron O’Brien says Staley was suspended from Hilliard Davidson High School in October 2016 after a student heard Staley discussing a shooting plot on a school bus. O’Brien says Staley created diagrams of different parts of the school, tried to recruit other students and wrote down what kinds of weapons and ammunition would be needed.

Staley’s attorney couldn’t be immediately reached for comment Friday. Staley has a scheduled court appearance Monday in Franklin County Common Pleas Court.