A 20-year-old Virginia man who had made threatening statements about the television show 'South Park' was arrested Wednesday and charged with supporting the Somalia-based terrorist group al-Shabab after he allegedly tried to board a flight to Africa with his infant son. The man, a Muslim convert from Fairfax County, Va., named Zachary A. Chesser, had been in e-mail contact with Anwar al-Awlaki, a U.S.-born radical cleric now hiding in Yemen, prosecutors said. Chesser was briefly in the news in April after he posted on the Internet a statement that the makers of 'South Park' might be killed for portraying the prophet Muhammad in a bear suit. In an unrelated case Wednesday, another American convert to Islam, Paul G. Rockwood Jr., 35, of King Salmon, Alaska, admitted that he had been radicalized by reading al-Awlaki's tracts on the Web and had prepared a list of 15 people he believed should be killed for 'desecrating Islam.' According to his guilty plea in federal court in Anchorage, Rockwood gave the list to his wife, Nadia Piroska Maria Rockwood, but neither is accused of taking any steps toward harming the people on the list, whom prosecutors did not name. Rockwood, who previously lived in Virginia but moved to Alaska in 2006, agreed to an eight-year sentence for making false statements during a terrorism investigation. Nadia Rockwood, who also admitted making false statements, agreed to five years of probation, to be served in her native Britain, according to court papers. The terrorism-related charges against two Americans, both devotees of al-Awlaki, are part of a marked increase in homegrown extremism in the United States, often influenced by radical material on the Internet. According to Justice Department statistics, 19 U.S. citizens were charged in international terrorism cases in 2009 and 15 more so far this year. In case after case, investigators have discovered the writings and recordings of al-Awlaki. U.S. intelligence officials believe he played a role in organizing the attempted bombing of a Detroit-bound airliner Dec. 25, and this year he became the first U.S. citizen to be placed on the CIA's capture-or-kill list. Chesser, according to an FBI affidavit, sent several e-mail messages to al-Awlaki, receiving two replies. In April, he posted on the website RevolutionMuslim.com a statement that the 'South Park' creators would 'probably end up like' Theo Van Gogh, a Dutch filmmaker killed after being accused of attacking Islam. Chesser told FBI investigators that he twice tried to fly to Somalia to join al-Shabab, which has links to al-Qaida. The second time, on July 10, when he tried to board a plane bound for Uganda, he was told he was on the no-fly list, charging documents say. He had told his wife he was taking their young son along for 'cover,' the documents say. 