Richard Dart's extremist beliefs were laid bare in a television documentary made by his step-brother.
The film, called My Brother the Islamist, was broadcast on BBC Three in 2011 and featured Dart having close contact with hate preacher Anjem Choudary and declaring that he backed sharia law to eradicate evil in UK society.
Bearded Dart, who had only been a Muslim for six months at that point, said: "I support the cause of jihad, that's part of being a Muslim."
His step-brother, filmmaker Robb Leech, had not seen him for three years before making the documentary, which he said was part of his attempts to understand why Dart had embraced murderous extremism.
The 30-year-old moved from their home town Weymouth in Dorset to east London, where he spent his time attending extremist Islamic lectures, preaching on the streets and taking part in controversial demonstrations.
One gathering was held outside the US embassy in London on the anniversary of 9/11 and saw Choudary's supporters burning an American flag.
Dart said he wished he could have been the one to start the fire.
In the broadcast he is also seen walking around Weymouth complaining that British culture was becoming "more homosexual" with "men dressing like women".
He also bemoans the fact that people are walking around "half naked".
Back in London, he is seen telling another white Muslim who has just come to Britain that there are "many misconceptions" about al-Qa'ida.
Dart says: "The worst of the Muslims is better than the best of the kuffar (non-believers), that's a fact.
"That's why the kuffar will be in hell fire for eternity."
As he hands out Islamic leaflets to passers-by in east London he even approaches a Police Community Support Officer and makes an apparent reference to his co-conspirator Alom.
Alom was a PCSO and had also previously been in the Territorial Army before he rejected mainstream society.
Dart says: "There is one brother that I'm very close with, he used to be in the police but he left it."
The son of two teachers, the former BBC security guard came under the influence of extremist preacher Choudary, former head of two now-banned organisations Al-Muhajiroun and Islam4UK.
Choudary was master of ceremonies at Dart's official conversion to Islam, a film of which was posted on YouTube, and the pair were together for Dart's first televised interview.
The documentary finishes with Dart travelling to Mecca to go on pilgrimage, talking about a demonstration called British Soldiers Can Burn In Hell, planned while he was away.
It remains unclear exactly how his new-found religious beliefs spiralled into hate-filled extremism.