Grand jury subpoenas were issued in the hazing investigation at Maine West High School.
Several former and current Maine West students reported that they were victims of hazing, while on school athletic teams.
Some said they were sexually assaulted.
Last month the school district decided to suspend Maine West coach Michael Divincenzo, without pay, before it dismissed him.
That coach has appealed the ruling and denied any knowledge of hazing to Des Plaines police.