Adam Gadahn was the grandson of a Jewish doctor.
He was raised on a ranch in Riverside County and later lived in Orange County, where he found his way to the Islamic Center of Orange County. There, he became increasingly radical in his beliefs, acquaintances and officials would later say, falling under the influence of two radical Muslims, Khalil Deek and Hisham Diab.
He became so angry and outspoken that he was eventually kicked out of the center.
Then in 2004, Gadahn emerged on television, making threats against the United States in a suspected Al Qaeda video. That year, the U.S. identified him as being linked to Al Qaeda and a potential threat in the United States.
A decadelong manhunt for Gadahn ended in January when he was killed during the U.S. counter-terrorism operation announced by President Obama announced on Thursday that also accidentally killed two innocent hostages.
Gadahn had been on the FBI's list of most wanted terrorists and was the first American since the World War II era to be charged with treason. The government offered a $1-million reward for information leading to his arrest.
He was indicted in 2006 by a federal grand jury in Orange County on charges of providing material support to Al Qaeda by appearing in the 2004 video as well as others.
In one video cited in the indictment, Gadahn acknowledged that he had "joined a movement waging war on America and killing large numbers of Americans." Wrapped in a head scarf that revealed only his eyes, Gadahn also declared that the Sept. 11 attacks on Washington and New York "notified America that it's going to have to pay for its crimes and pay dearly."
Friends say Gadahn fell under the spell of Diab, an accountant who lived in the Little Gaza section of Anaheim. Diab was a follower of Omar Abdel Rahman, known as the "blind sheikh," who is serving life in prison for the 1993 World Trade Center bombing. Gadahn and Diab shared extremist views and considered leaders of the Islamic Center who worked with Christians and Jews "infidels," the center's president told the Los Angeles Times in 2006.
According to Times reports, Gadahn converted to Islam in 1995 and became involved in Diab's group, Charity Without Borders, a purported aid organization with ties to the Middle East. U.S. officials shut down the group after 9/11.
Officials said Gadahn traveled to Pakistan in 1998, where he eventually found his way to a terrorist camp.
After 9/11, U.S. intelligence believed Gadahn's videotaped message on behalf of the terrorist group was meant for an American audience.
"It is not some masked guy with a rifle saying, 'Death to America,' " one senior U.S. law enforcement official told The Times in 2006. "It is an American. And his target audience is the U.S."
To this day, people who knew Gadahn growing up struggle to understand who he became.