WJOL News has confirmed that Joliet District 86 received four threatening messages that were left on school attendance voicemails prior to classes starting on Monday. The District notified law enforcement officials immediately and launched an investigation into the matter. The Joliet Police Department and the Will County Sheriff’s Department have determined that the four messages left on school voicemails are not credible and that the schools, students and staff are safe. The messages were left on voicemails at Dirksen, Eisenhower, Farragut, and Sandburg schools. Letters will be sent home with students at those schools with additional information for parents or legal guardians. An investigation into the matter is ongoing.