Western intelligence sources think that Californian-turned-al Qaeda propogandist Adam Gadahn may have died in CIA-directed attacks by unmanned predator aircraft on the border between Pakistan and Afghanistan, says a writer in the U.K.'s Telegraph newspaper. Gadahn, who was charged with treason by U.S. authorities, could have died as long ago as January.

Nothing has been heard from him for months, leading intelligence experts to conclude that he may be dead.

Mr Gadahn has been credited with helping transform al-Qa'eda's al-Sahab propaganda wing into a slick operation which communicates in fluent English and produces professional quality DVDs, including one for Osama bin Laden last year....

Jihadists around the world will be watching as closely as intelligence officials this week to see whether Mr Gadahn - also known as Azzam al-Ameriki - produces a new video message to mark September 11, as he has done every year since 2003.

If there is no message it will be taken as near certain confirmation that he is dead – killed either in a strike by Hellfire missiles, or perhaps by jihadi colleagues who have grown jealous of his success.

Mr Gadahn is now thought to have been killed in an attack launched from a remotely piloted aircraft in January which killed al-Qaeda's then military commander, Abu Laith al-Libi, in Mir Ali, Waziristan.

Gadahn grew up in Southern California as Adam Pearlman, the son of a former psychedelic musician. He was profiled last year in the New Yorker.