ALEXANDRIA, Va. -- A northern Virginia man best known for threatening the creators of the "South Park" cartoon for their perceived mockery of the prophet Muhammad has pleaded guilty to supporting an al-Qaida linked terrorist group.

Twenty-year-old Zachary Chesser of Bristow, Va., admitted that he tried to join the join the al-Shabab terror group in Somalia earlier this year and that he posted online propaganda on their behalf. Court papers allege he took his infant son with him to the airport to make his travel appear more innocuous.

In a plea hearing Wednesday in federal court in Alexandria, Chesser also pleaded guilty to two counts of communicating threats and soliciting crimes of violence.

Chesser faces a maximum of 30 years in prison. Defense attorneys agreed that they would ask the judge for no lower than 20 years.