Mohammed Hamzah Khan, who arrived at O'Hare International Airport Saturday with a roundtrip ticket to Istanbul, was charged with one count of attempting to provide material support to a foreign terrorist organization, the Justice Department said.
Law enforcement agents who searched Khan's home in the southwest Chicago suburb of Bolingbrook said they had found multiple handwritten letters by Khan and others expressing support for the IS group, including travel plans and references to IS and jihad.
Authorities said the investigation was still ongoing.
Khan appeared Monday morning in US District Court and remains in custody. He is scheduled for a detention hearing at 10:30 am on Thursday.
Providing material support to a foreign terrorist organization carries a maximum penalty of 15 years in prison and a USD 250,000 fine.