KANSAS CITY, Kan. (AP) — A Topeka man charged with plotting to detonate a 1,000 pound bomb outside Fort Riley is preparing to appear before a federal magistrate.

John T. Booker Jr.’s hearing Tuesday in federal court in Kansas City, Kansas, comes after a grand jury handed down a three-count indictment for the 20-year-old last week. The hearing is to inform Booker of its details.

Prosecutors say Booker was arrested while trying to arm what he thought was a bomb outside the Army base. Booker told an FBI informant he wanted to kill Americans and wage jihad for the Islamic State group, according to a criminal complaint filed against him.

The imam at the Topeka mosque Booker frequented said he suffers from bipolar disorder, which is characterized by mood swings that can affect functioning.