(CNN) -- Federal authorities are using words uttered by the co-founder of a radical Islamic group to charge him with threats against the creators of "South Park."
A criminal complaint alleging the communication of threats was filed in Virginia late last week against Jesse Curtis Morton, also known as Younus Abdullah Mohammad.
A senior law enforcement source Thursday told CNN, which interviewed Morton in 2009, that the suspect is believed to be in Morocco, where he maintains Islampolicy.com, an English-language website propagating pro al Qaeda views.
That website is a successor to Revolutionmuslim.com.
Morton, a former resident of Brooklyn, New York, is the second person charged in the "South Park" case.
In February, 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 recent 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 -- despite their claims -- threats, 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.
Revolution Muslim's 2008 co-founders, Yousef al-Khattab and Morton, were both interviewed by CNN's Drew Griffin 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.
He told Griffin he did not encourage violence on U.S. soil.
The government affidavit cites the CNN interview.
"We're commanded to terrorize the disbelievers," Morton told Griffin. "The Quran says very clearly in the Arabic language ... this means 'terrorize them.' It's a command from Allah."
Morton said he did not define terrorism as killing innocent civilians. "I define terrorism as making them fearful, so that they think twice before they go rape your mother or kill your brother or go into your land and try to steal your resources."
Efforts by CNN Thursday to reach Morton were unsuccessful.
The senior law enforcement source told CNN's Paul Cruickshank if Morton crosses into U.S. jurisdiction or into a country with extradition treaty with United States, he will be arrested.
Morocco and the United States do not have a bilateral extradition treaty, according to the Congressional Research Service.
The source said the complaint was linked to the Chesser case and that Morton's activities were a concern to U.S. counterterrorism agencies.
Revolutionmuslim.com was the subject of a CNN investigation for its radical rhetoric supporting "jihad" against the West and praising al Qaeda leader Osama bin Laden. Its organizers insisted they acted within the law and seek to protect Islam.
In April 2010, Revolutionmuslim.com posted an entry that included a warning to "South Park" creators Trey Parker and Matt Stone that they risked violent retribution after the 200th episode of the cartoon series included a satirical discussion about whether an image of the prophet could be shown. In the end, he was portrayed disguised in a bear suit.
"We have to warn Matt and Trey that what they are doing is stupid," the posting on Revolutionmuslim.com says, "and they will probably wind up like Theo Van Gogh for airing this show. This is not a threat, but a warning of the reality of what will likely happen to them."
Dutch filmmaker Theo van Gogh was stabbed to death on a street in Amsterdam, Netherlands, by an Islamic extremist in 2004. He became the target of radical Muslims after releasing a short film about oppression of Islamic women in Europe.
Revolutionmuslim.com last spring said despite the provocative post, the site was calling simply for protest, not violence.
Chesser and Morton "purported to deny" that they were inciting violence, according to the FBI agent's affidavit, but said "our position remains that it is likely the creators of 'South Park' will indeed end up like Theo Van Gogh."
In December 2010, Revolutionmuslim.com co-founder al-Khattab told CNN the defunct website became a "bug light for Muslim misfits."
And he said he regretted that his message was taken by some as a justification to attack civilians.
"It was an idiotic thing, looking back on things now," al-Khattab told Griffin.
Morton in 2009 told CNN that "Americans will always be a target -- and a legitimate target -- until America changes its nature in the international arena."
CNN's Drew Griffin, Paul Cruickshank and Tim Lister contributed to this report.