Donald Robin was sentenced to 17 years in prison for his role in planning school shootings.
Three other charges were dropped as part of a plea agreement. Nine years of the sentence were suspended. Robin could serve six years.
Robin entered a guilty plea to conspiracy to commit murder. He cried while reading an apology before Judge Christopher Lee.
Robin will also testify against fellow defendant John Schultz who is scheduled for a suppression hearing next month. A jury trial is scheduled for June 8.