A suburban Chicago 19-year-old has been charged by federal prosecutors for trying to travel overseas to join the Islamic State.

Authorities arrested Mohammed Hamzah Khan, a U.S. citizen, Saturday night at Chicago O’Hare Airport as he was about to depart to Vienna en route to Istanbul, according to the U.S. Attorney’s Office for the Northern District of Illinois. He was charged Monday morning in federal court with one count of attempting to provide material support to a foreign terrorist organization.

While law enforcement saw Khan go through security in the airport, federal agents found notes in Khan’s home that were written by Khan and possibly others expressing support for the Islamic State, the criminal complaint said.

One such note, written in Arabic, read, “Islamic State in Iraq and Levant. Here to stay. We are the lions of the war… My nation, the dawn has emerged,” the criminal complaint said.

Khan, who lived with his parents, also left a three-page letter for them in his bedroom, the complaint stated. In the letter, he tries to explain why he’s traveling, writing that he was upset with the decline of Western societies and with having to pay taxes used to kill Muslims. “I extend an invitation, to my family, to join me in the Islamic State,” the letter read, according to the complaint.

A round-trip ticket was bought for Khan with a return date for later this week, the criminal complaint said. During an interview with the FBI at the airport, Khan told agents he planned on remaining in the Middle East permanently, and “he expected to be involved in some type of public service, a police force, humanitarian work or a combat role,” the complaint said.

FBI officials arrested Khan “without incident,” the U.S. Attorney’s Office said, and he will remain in federal custody until a Thursday morning hearing. Khan faces up to 15 years in prison.

Khan appeared in court Monday morning, where his father tried to calm his crying mother, the Chicago Tribune reported.

Defense attorney information for Khan was not immediately available.

[This post has been updated.]