By Dominic Casciani
BBC News community affairs
So who exactly is Omar Bakri Mohammad? Is he, as the Sun declared, a "Bombers' Pal" or merely a brilliant self-publicist? And now he has suddenly left the UK - will he be back?
Omar Bakri Mohammad says he would never co-operate with police
The self-styled radical cleric caused a media storm after the London bombings, declaring that the only people he blames for the London bombings are the government and British public. And now, the government has named him as one of three people to be investigated for having possibly committed treason.
Asked whether he condemned those inspired by Osama Bin Laden, he said: "Why [would] I condemn Osama Bin Laden for? I condemn Tony Blair. I condemn George Bush. I would never condemn Osama Bin Laden or any Muslims." So what do we know of Bakri and the other two named men, Abu Izzadeen and Abu Uzair?
Ever since 9/11, Bakri Mohammad has been a hate-figure of the highest order for wide sections of the British press.
To what degree he is a genuinely dangerous individual, or simply someone who would like other people to think he is, remains extremely difficult to quantify.
His public pronouncements have outraged many people. But, at the same time, his organisation appears to be small and unattractive to many of the young Muslims he seeks to attract, his activities apparently largely focused on parts of London and Luton.
Born in Syria
Bakri Mohammad was born in Syria in the late 1950s, where he became involved in the Muslim Brotherhood, a revolutionary organisation which provided the foundations for Islamist political ideology.
In the West, the organisation is popularly thought to have a violent agenda, although many analysts say its character is far more complex.
OMAR BAKRI MOHAMMAD
Born Syria in 1958
Involved in Muslim Brotherhood
Travelled through Middle East
Established Al Muhajiroun
Sought asylum in the UK
"Disbanded" Al Muhajiroun in 2004
Suddenly left UK for Lebanon, August 2005
A lot of opposition politicians in Egypt associate with the banned movement - but many of those who believe in violent means quit to form splinter groups, including Ayman Al-Zawahiri, the Egyptian surgeon considered to be Osama Bin Laden's chief ideologue.
What happened to Bakri Mohammad is unclear. He is believed to have gone from the Muslim Brotherhood to Hizb ut Tahrir, another banned Islamist organisation, and later travelled around the Middle East, eventually fleeing in the 1980s for political asylum in the UK.
Bakri Mohammad later fell out with fellow London-based ideologues such as Sheikh Abu Hamza al-Masri, a former nightclub bouncer currently awaiting trial on one anti-terrorism-related charge and a number of further alleged racial-hatred offences.
Investigation: Abu Uzair and Abu Izzadeen
The Syrian activist and his band of followers have spent the subsequent years trying to develop the "Al Muhajiroun" organisation in the UK.
By 2001 it had become a well-known radical group which had sought to recruit in Muslim communities, principally outside mosques in poorer areas - although it's not clear whether its membership has ever been anything other than a handful of disenchanted young Muslims.
Within the Muslim community itself, it was largely reviled for pulling off clever media stunts that attracted media attention, such as describing the 9/11 hijackers as the "Magnificent 19".
Bakri Mohammad says he disbanded the group in 2004. But government remains unconvinced - and there is a widespread belief among those who watch him that many of his followers have simply reconstituted themselves in two new groups.
Abu Ghurabaa website: Similar to former Al Muhajiroun site
One of these is the Saviour Sect, an organisation that theatrically stormed a Muslim general election event in April 2005.
The other is called Abu Ghurabaa. The two other men named as potentially facing a treason investigation have represented this body in news interviews.
The groups have very similar views and, in cyberspace at least, have offered links to each other.
In the case of Abu Ghurabaa, its website uses images and words that present the US and its allies as oppressing Muslims. It asks supporters to "co-operate" in "eradicating" man-made laws such as the US or UN constitution.
Among the links promoted on the site, is one to a website which includes articles justifying suicide bombings and other discussions familiar among Islamist movements.
While he is informally banned from mosques, Omar Bakri Mohammad's words have regularly found other outlets, principally the mainstream national media and the internet.
It is perhaps this latter outlet that concerns both Muslim leaders and the security services as Islamists used the web to espouse their radical take on their faith, including justifications for acts of violence.
New group: Bakri Mohammad thought to be the inspiration
In the case of Omar Sharif and Asif Hanif, two British men who became Hamas suicide bombers in 2003, investigators later found that at least one of the pair had been interested in the activities of Al Muhajiroun.
Journalist Jon Ronson had unfettered access to Omar Bakri Mohammad for his book "Them: Adventures with Extremists".
He confesses to having enjoyed the cleric's company, even after a bizarre visit to his Surrey "training camp" during which he was revealed to be a Jew in the midst of an apparently Israel-hating organisation.
"I have had three conversations with him since then," he says. "I phoned him on the day of the 9/11 attacks and he clearly said to me that it was a terrible thing to happen - and he meant it."
Jon Ronson believes that Bakri Mohammad was so taken aback by the Al Qaeda attack that he didn't actually know how to react.
After some media prodding, says Jon Ronson, the cleric appeared to revert to type and once more play to the image of a man organising jihad from a north London suburb.
"People have suggested that he was friendly to me and then as soon as my back turned he went back to being some kind of Bond villain character. I don't think that's true.
"He recognises that you don't get to become a charismatic leader without being someone who people like."