In her farewell letter as she was leaving to join the Islamic State group, Jaelyn Young told her family she was guilty.
"I found the contacts, made arrangements, planned the departure," prosecutors say she wrote last August. "I am guilty of what you soon will find out."
On Tuesday, she admitted the same to a federal judge in Aberdeen, Miss., pleading guilty to one count of conspiring to provide material support to a terrorist organization.
U.S. District Judge Sharion Aycock will sentence the 20-year-old Young at a later date. The former Mississippi State University student faces up to 20 years in prison, $250,000 in fines and lifetime probation.
Her fiancé, Muhammad Dakhlalla, pleaded guilty March 11 to a similar charge and also awaits sentencing.
The daughter of a school administrator and a police officer who served in the Navy reserve, Young is a former honor student, cheerleader and homecoming maid at Vicksburg's Warren Central High School.
Prosecutors have said Young converted to Islam while studying chemistry at Mississippi State University, led toward the Islamic State group in part by online videos. Like Young herself, prosecutors have said she's the one who prodded Dakhlalla into the plan to join the terrorists.