Since 2004, Gadahn has appeared in a series of videos in which he praises the Sept. 11, 2001, hijackers and claimed, "The streets of America shall run red with blood." The first video of Gadahn was initially aired by ABC News in October 2004. "Adam Gadahn is an American citizen who made a choice. He chose to join our enemy and to provide it with aid and comfort by acting as a propagandist for al Qaeda," U.S. Deputy Attorney General Paul McNulty said in announcing the indictment.

Gadahn, who has also called himself Azzam the American in Internet videos, is the first person to face treason charges in the United States since a l U.S.-Japanese citizen was charged in 1952 for abusing U.S. prisoners of war during World War II.

Other famous treason charges included the case of Iva Ikuko Toguri d'Aquino, aka Tokyo Rose, who broadcast propaganda during the war to demoralize U.S. soldiers. The indictment charging him with treason used his own words as the basis for the charge.

The FBI added Adam Gadahn to the Most Wanted Terrorist list and the U.S. State Department is offering a reward up to $1 million for his arrest.

In a September 2005 video, he described the 9/11 attacks as "the blessed raids on New York and Washington." In the same video he threatened, "Yesterday, London and Madrid. Tomorrow, Los Angeles and Melbourne, Allah willing."

While many Americans reflected during the fifth anniversary of the 9/11 attacks, Gadahn called the United States "enemy soil" in a video released that day.

The indictment does not include information on any specific terrorist plots or mention his relations with senior al Qaeda planners, and some legal scholars say the treason charge is an unusual one to pursue.

"While there appears to be ample basis for a material support charge, the treason charge could prove more difficult to sustain," George Washington University professor Jonathan Turley said. "First and foremost, there is the absence of any traditional definition of an enemy state."

But McNulty laid out the charges at the press conference today announcing the indictment.

"We have a U.S. citizen who has betrayed the country, according to the charges, the allegations, and joined up with this enemy to communicate that fear. It brings a lot of different factors together and makes it suitable for treason," McNulty said.

By placing him on the FBI's Most Wanted Terrorist list and the State Department offering a reward of up to $1 million for information leading to Gadahn's arrest, U.S. officials hope tips will start coming in. He was last known to be in the United States in 1999, according to an FBI official, and U.S. officials believe he is currently in Pakistan.

"It's time now to get the message out in order to get this person in our custody, perhaps to find the assistance that we need," McNulty said.

Gahdan's road to becoming an influential member of al Qaeda took a twisted road from his upbringing in California. He went from living on a goat farm, listening to heavy metal music as a teenager to joining al Qaeda.

In a 1995 Internet posting Gadahn wrote, " I had become obsessed with demonic heavy metal music. My entire life was focused on expanding my music collection. I eschewed personal cleanliness and let my room reach an unbelievable state of disarray."

According to his posting, Gadahn became intrigued with Islam while surfing the internet.

"I began to look for something else to hold on to. ... I begin [sic] to visit the religion folders on AOL and the Usenet newsgroups, where I found discussions on Islam to be the most intriguing," he wrote.

According to U.S. law enforcement and intelligence officials, Gadahn traveled from California to Pakistan and became involved with Islamic extremists after meeting Khalil Deek in California in the late 1990s. According to the 9/11 Commission, Deek was involved in computer activities for terrorists and is "believed to be involved in millennium plot to destroy tourist landmarks in Jordan."

According to a U.S. official Gadhan's membership in al Qaeda was first disclosed to FBI and U.S. intelligence officials through several detainees captured in Afghanistan, including Abu Zubaydah, a high-ranking al Qaeda recruiter who was captured in 2001.

His role as an Arabic and English speaker has allowed him to perform translations for al Qaeda, and he has helped them prepare videos other than the five he has appeared in.

"He is being used heavily because he is someone that al Qaeda can throw up in our faces," one U.S. intelligence official said today. Gadahn's journey to the other side of the world eventually intersected with top al Qaeda members, allowing him to become one of the terror group's key spokesmen; his role as a propagandist grew. "It is no accident that many of the videos from Osama bin Ladin and Ayman Zawahiri are produced with English subtitles," Randall Blake, the al Qaeda unit chief for the National Counterterrorism Center, said last month in testimony before Congress.