U.S. officials believe with a high degree of confidence that missing Southern Californian Adam Gadahn is the self-described American al Qaeda who threatened to kill thousands of his countrymen in a videotape obtained and broadcast by ABC News two weeks ago.
"No, my fellow countrymen you are guilty, guilty, guilty, guilty," the man identified only as "Azzam the American" said. "After decades of American tyranny and oppression, now it's your turn to die. Allah willing, the streets of America will run red with blood matching drop for drop the blood of America's victims."
A senior U.S. official says officials concluded that Azzam the American was Gadahn after speaking to his family in Southern California, showing the tape to captured al Qaeda operatives and conducting weeks of technical analysis. Although all indications are of a positive match, officials do caution that there is a small margin of error in the analysis and they cannot be absolutely certain of the speaker's identity.
Among other steps, intelligence officials compared the voice of Azzam to footage of a teenage Gadahn discussing environmental projects nearly 10 years ago on a cable television segment in California. Gadahn, who would now be 26, is wanted for questioning by the FBI in connection with possible terrorist threats against the United States.
FBI Director Robert Mueller said in a May press conference that Gadahn was associated with al Qaeda leader Abu Zubaydah in Pakistan, and that he attended terrorist training camps in Afghanistan.
"He is known to have performed translations for al Qaeda as part of the services he has provided to al Qaeda," Mueller said.
"He's so angry at the United States, that he's obligated to seek revenge," said Jack Cloonan, a former FBI agent who is now an ABC News consultant.
Gadahn was born Adam Pearlman, the son of 1960s psychedelic musician Phil Pearlman, and raised in Orange County on a goat farm. He was home-schooled until the age of 15, at which point he moved in with his grandparents in Santa Ana.
Six years ago, Gadahn left California for Karachi, Pakistan, where his parents last heard from him in the months after Sept. 11, 2001. He never kept up a regular correspondence, his father said, and seemed to be making a life for himself when he last called in February 2002.
"He had got married and was settling down and it didn't seem like he was involved in anything like this as far as we could tell," Pearlman said.
After first denying it, officials say the parents admitted to FBI agents that the person on the tape could be their son.
Aunt Nancy Pearlman said Gadahn was just a typical teenager with shifting interests. "Adam was a very loving, caring, intelligent young man," she said. "He was listening to hard rock music. He gave that up when he got religious."
At the age of 17, Gadahn posted a statement online about his conversion to Islam called "Becoming Muslim." Rejecting what he called his obsession with demonic heavy metal music, Gadahn rejected evangelical Christianity and found a home in Islam.
"I discovered the beliefs and practices of this religion fit my personal theology and intellect as well as basic human logic," he wrote. "Islam presents God not as an anthropomorphic being but as an entity beyond human comprehension, transcendent of man, independent and undivided."
Gadahn attended a local mosque in Orange County, from which he was expelled after attacking an employee.
The imam of the mosque, Haitham Bundjaki, said he recognized the voice on the al Qaeda tape as Gadahn's.
"Unfortunately, I know the guy," Bundjaki said. "He thought I was too Americanized. Of course, he's an American. The few people he was with I think they put things in his head that led him to be that way."