Pakistan says U.S.-born suspect in custody is not Gadahn

The suspected Al Qaeda operative arrested in Karachi over the weekend was not the Southern California native wanted by the United States on treason charges for his involvement in the terrorist network, Pakistani intelligence officials said Monday.

Pakistani security officials had initially asserted that the Islamic extremist they had captured in the country’s largest city late Saturday was Adam Gadahn of Riverside, a spokesman and top propagandist for the Al Qaeda terrorist network.

However, by early Monday morning, doubts had arisen about those reports. U.S. officials said they were skeptical and added that they had received no indication Gadahn was the suspect arrested in Karachi.

Later Monday, Pakistani intelligence officials reversed themselves and said the man arrested was actually Abu Yahya Mujahideen al Adam, a Pennsylvania native and suspected operative for Al Qaeda. The intelligence officials said Adam had been transferred to Islamabad for interrogation but would not give any further details.

U.S. officials in Washington said Monday that they had been unable to verify that Pakistan had arrested an Al Qaeda operative who was born in Pennsylvania.

Several officials said they were unfamiliar with the name Abu Yahya Mujahideen al Adam. “That’s not one that really rings bells,” a U.S. official said.

Gadahn, 31, remains at large. He is on the FBI’s list of most wanted terrorists and is the first American since the World War II era to be charged with treason. The U.S. government has offered a $1-million reward for information leading to his arrest.

Gadahn was indicted in 2006 by a federal grand jury in Orange County on charges of providing material support to Al Qaeda by appearing in videos on five different occasions between Oct. 27, 2004, and Sept. 11, 2006, with the intent “to betray the United States.”

His latest video was posted on extremist websites Sunday. In it, he urged Muslims serving in the American military to emulate Maj. Nidal Malik Hasan, the Army psychiatrist accused of shooting to death 13 people at the Ft. Hood military base just outside Killeen, Texas, on Nov. 5.

In the video, Gadahn called Hasan “the ideal role model for every repentant Muslim in the armies of the unbelievers and apostate regimes.”

alex.rodriguez @latimes.com

Times staff writer David Cloud in Washington contributed to this report.