Adam Gadahn: The goat farmer's son and death metal obsessive who became one of Al Qaeda's most famous members

John Walker Lindh, Richard Reid, Adam Gadahn: these Western-born fanatics have long captivated our attention. Their fiery rhetoric appearing as strangely unconvincing as their bushy beards, as if these British or American-born loners turned terrorists were actors in a bad film.

Yet Adam Gadahn, the former death metal fan and son of a goat farmer from rural Southern California who was killed in a US drone strike in January, rose from an alienated white Muslim convert to one of Al Qaeda's most foremost propagandists with a $1m bounty on his head.

In dozens of broadcasts published from the lawless tribal region of Pakistan where he is believed to have been based since leaving the US in the late 1990s, Gadahn raged against President Barack Obama and the West and defended attacks on the US including the 2001 bombing of the World Trade Centre.

Gadahn was killed in an airstrike on an Al Qaeda compound in northern Pakistan in January, US President Barack Obama announced Thursday, in an operation that also resulted in the deaths of American hostage Warren Weinstein and Italian NGO worker Giovanni Le Pollo.

The American jihadi had become the first US citizen to be charged with treason in over 50 years in 2007, when his affiliation with Al Qaeda and its leader Aymann al-Zawahiri was laid bare in a string of videos published on the internet and featuring Gadahn, who called himself Azzam the American.

In a profile of the 36-year-old published this week, the New York Times reported that Gadahn grew up without running water on a 40-acre farm in Southern California. He converted to Islam at 17 and left the US during the 1990s, with relatives saying that he was seeking a less materialistic life.

He first appeared with face covered in an Al Qaeda propaganda video in 2004, warning that: "the streets of America shall run red with blood". On the fifth anniversary of September 11 in 2006, he appeared unmasked in a forty-five minute documentary titled 'An Invitation to Islam'.

Over the following years Gadahn would give a number of other broadcasts and as believed to be the brains behind al-Sahab, Al Qaeda's media arm, advising senior figures in the group including al-Zawahiri. His compound was close to where Western hostages were being held in the lawless Waziristan region of Pakistan.

Gadahn would often speak in Arabic but over the years had started to develop a Middle East accent when speaking English. At the same time, the anecdotes and recollections with which he peppered his anti-Western tirades would include references to his former life in America.

In a 2007 New Yorker profile, the magazine suggested that Gadahn had been the first Al Qaeda operative to lace a religious threat with a reference to Monopoly: "If you die as an unbeliever in battle against the Muslims, you're going straight to hell, without passing Go"

Like Lindh, who fought for the Taliban in Afghanistan and was arrested and jailed as an enemy combatant in 2001, Gadahn had converted to Islam as a teenager and become a fanatic extremely quickly, friends that knew him at the time told the New Yorker.

Prior to his conversion to Islam, he had been an obsessive fan of death metal, a genre of heavy metal associated with heavy, brutal guitar riffs and lyrics that glorify death, disease and misanthropy. He swapped tapes and letters with fans across the US, the New Yorker revealed, and sketched flyers and promotional material for obscure bands from across the world.

That obsessiveness quickly manifested itself in his newly found faith, and Gadahn was rapidly radicalised by a group of equally fanatical Muslims who attended his mosque in California. After an altercation with his former Imam, Gadahn left the US for Pakistan where he gradually became involved in extremist circles in the north west of the country and eventually met al-Zawahiri.

Gadahn's death comes at a time when the spotlight has firmly shifted from al-Qaeda and into Islamic State, and when the terrorist group that was once a byword for horror and barbarism has faded into the background as IS atrocities in Iraq and Syria have dominated news in the West.

Like Lindh, currently serving 20 years in a maximum security prison, and Reid, the wannabe shoe-bomber who is serving 110 years for trying to blow up a commercial airliner, Gadahn's terrorist career has come to an abrupt and final conclusion. All that is left now is for the 36-year-old California-born jihadi to fade into obscurity – much like the death metal bands whose covers he once illustrated.