(CNN) -- An American charged with communicating threats against the creators of "South Park" is in federal custody on U.S. soil, a senior U.S. counter-terrorism official told CNN.
Jesse Curtis Morton was the co-founder of a radical New York City-based Islamist group supportive of al Qaeda's worldview.
Morton, also known as Younus Abdullah Mohammad, was taken into U.S. custody in Rabat, Morocco, on October 28, according to court documents. He was first arrested by Moroccan authorities in May after being indicted in the United States. By October 31, he was back on U.S. soil, the official said.
In a detention hearing at federal court in Alexandria, Virginia, on November 4, Morton was ordered detained until trial, according to court documents. He has yet to enter a plea. In May, Morton, a former resident of Brooklyn, New York, became the second person charged in the "South Park" case.
Earlier this year, Zachary Adam Chesser, 21, who admitted to posting online threats, was sentenced to 25 years in prison.
Chesser, a Muslim convert, encouraged violent jihadists to attack "South Park" writers for an episode that depicted the Prophet Mohammed in a bear suit, court documents said. Chesser posted online messages that included the writers' home addresses and urged online readers to "pay them a visit," the documents said. In an affidavit accompanying the complaint against Morton, FBI special agent Paula R. Menges said Morton, co-founder of the group called Revolution Muslim, worked with Chesser on a "clarification statement" after Chesser's postings.
The pair made website postings that were threats -- despite their claims otherwise, Menges said. The agent also contends the statement contained pages of justification under Islamic law for the death of those who insult Islam or defame its prophet.
Morton was interviewed in New York by CNN in October 2009. In the interview, Morton, a convert to Islam and one-time follower of the Grateful Dead, defended the September 11, 2001, terrorist attacks and argued that further attacks on Americans were justified. But he told CNN he did not encourage violence on U.S. soil.
A day before Morton was taken into U.S. custody in Morocco, CNN's Drew Griffin was e-mailed a nearly 6,000-word statement in which Morton disputed the case against him, and denied he ever participated in any effort to promote illegal violence.
"On May 25, 2011, I was arrested for writing a clarification statement connected to an admittedly inflammatory post on an Islamic website," Morton wrote. "The post was a reaction to the announcement that the 'South Park' cartoon was going to portray the prophet Muhammad, something considered sacrilegious and part of an ideological accompaniment to a comprehensive Western war on Islam. The clarification statement intended to reduce the sensationalist nature of an initial overreaction but is now being utilized by U.S. law enforcement to imprison me for something I am innocent of," he wrote.
CNN's Drew Griffin contributed to this report.