American Muslim Arrested in Denver

W A S H I N G T O N, July 23 -- As part of the federal government's ongoing investigation into possible al Qaeda activity in the United States, the FBI arrested a Seattle man it suspects of helping Osama bin Laden's terror network.

James Ujaama, 36, was arrested at a family member's home in Denver on Monday.

"The FBI came and got him," his mother, Peggi Thompson,told The Associated Press. "It's a federal charge of being a material witness. There's nothing I can do or anything right now. Nobody's saying anything."

Federal law enforcement officials refused to comment publicly on the arrest.

The FBI is investigating whether Ujaama, when he lived in London, associated with a radical Muslim fundamentalist who repeatedly has called for holy war against the West, sources told ABCNEWS.com.

Plus, sources said authorities are probing Ujaama's work on a Web site called stopamerica.org and a British site dubbed the "Ultimate Jihad Challenge." And officials want to know whether Ujaama took laptop computers to the Taliban in Afghanistan when the militant religious regime ran the country.

Sources told ABCNEWS federal prosecutors are considering charging Ujaama with aiding terrorists.

"If this individual indeed turns out to have concrete links to terrorists, to al Qaeda, then he is a big fish," said Matthew Levitt, an analyst with the Washington Institute for Near East Policy.

Suspect Denies Terror Activities

Ujaama, an African-American Muslim, has denied ties to terrorists. In an e-mail mailed last week to a columnist with the Seattle Post Intelligencer, Ujaama said he and his brother Mustafa were ready to challenge any criminal charges that may be brought against them.

"My brother and I are not terrorists and we should not have been charged in the media and harassed," James Ujaama said. Mustafa Ujaama was also briefly detained Monday, according to The Associated Press.

The brothers are well known in Seattle, where some community leaders have applauded their work to fight drugs and prostitution.