A Muslim leader in Orange County told KNBC-TV, Los Angeles, the man identified on the tape as "Azzam the American" is actually Adam Gadahn, who once worshipped at a mosque in Garden Grove before dropping out of sight in 1998.
The FBI identified Gadahn as a suspected al-Qaida member last May.
Haitham "Danny" Bundakji told KNBC he believed the bombastic Azza was actually Gadahn based on his mannerisms and his hands. An Arab headdress largely concealed Azzam's face.
The tape, which surfaced publicly earlier this week, ran nearly an hour and was primarily a series of threats of terrorist attacks against the United States.