On June 18 the Evanston Police Department and the U.S. Bureau of Alcohol, Tobacco, Firearms & Explosives (ATF) began to conduct a joint investigation into the placing of an explosive device in the rear of the Evanston Police Department’s Howard Street Outpost, 633 Howard St., Evanston. On that date a person of interest was identified by the Evanston Police Department, said Commander Tom Guenther, public information officer of the Evanston Police Department. 

The continuing  joint investigation further determined and implicated the person of interest as the lone offender in this incident, said the Commander. 

On June 20, the U.S. Attorneys Office identified a 19-year old Chicago man as the person who made and planted the explosive device. The man was formally charged on June 20 before a judge in U.S. District Court in Chicago with one felony count of possession of an unregistered destructive device.