Tuesday's sentencing of Mohammad Hassan Khalid of Ellicott City has been postponed.
He is linked to the case of 50-year-old Colleen "Jihad Jane" LaRose, who was sentenced Monday to 10 years in prison. Another woman, Jamie Paulin-Ramirez of Colorado, is due in court Wednesday.
The FBI says Khalid met LaRose and other extremists online when he was a 15-year-old honors student, and agreed to help them.
He is the rare juvenile detained on federal terrorism charges before turning 18.
In court documents, U.S. prosecutors say the 20-year-old native of Pakistan has assisted with global terrorism investigations since his 2011 arrest.
They are seeking a lengthy sentence, but less than the 15-year maximum.
