Police officers at a block of flats in Greenwich, south-east London, which was raided in connection with the killing of British soldier Lee Rigby. Photograph: Paul Hackett/Reuters
The two suspects in the butchering to death of a British soldier had been known to the domestic security service MI5 and the police over an eight-year period, but had been assessed as peripheral figures and thus not subjected to a full-scale investigation, it has emerged .
One of the two attackers was named as Michael Olumide Adebolajo, the man seen in dramatic video brandishing knives and justifying the attack as a strike against the west while his victim lay yards away bloodied and fatally wounded.
Adebolajo had complained of harassment by MI5 in the last three years after he came to the intelligence agency’s attention. The identity of the second suspect was not confirmed, but police on Thursday raided a house in Greenwich where Michael Adebowale, 22, was registered as a voter.
The admission came as the Ministry of Defence named the victim of the attack in Woolwich as Drummer Lee Rigby, a 25-year-old from Rochdale who had served in the army for seven years. Rigby, who had spent six months in Afghanistan in 2009, had a two-year-old son, and had been based in London since 2011.
The suspects, shot by police shortly after the incident, remain in separate but unidentified hospitals, too badly injured to be questioned.
Detectives investigating Rigby’s death also arrested a 29-year-old man and woman on suspicion of conspiracy to murder the soldier, suggesting there may have been a wider conspiracy to carry out the attack. The 29-year-old woman was arrested at a flat in Greenwich, south-east London.
Parliament’s intelligence and security committee would examine the wider role of the police and MI5, David Cameron said on Thursday, an inquiry that is expected to address any lessons that may need to be learned after counterterrorism officials decided not to monitor the suspects.
Speaking in Downing Street before a visit to Woolwich, Cameron said: “You would not expect me to comment on this when a criminal investigation is ongoing, but what I can say is this: as is the normal practice in these sorts of cases, the Independent Police Complaints Commission will be able to review the actions of the police, and the intelligence and security committee will be able to do the same for the wider agencies, but nothing should be done to get in the way of their absolutely vital work.”
There were some suggestions that one of the two men may have tried to visit Somalia; Whitehall sources did not deny reports that one of the suspects was stopped while trying to travel to the war-torn east African country. Somalia is feared by counterterrorism officials to be a training ground for violent jihadists.
The extremist cleric Omar Bakri Mohammad, who has been expelled from Britain, told the Guardian he had tutored Adebolajo in Islam after he converted to the religion in 2003. He was the former leader of al-Muhajiroun, an organisation banned for professing extremist views. Mohammad described Adebolajo as a shy man who had been angered by the Iraq invasion, and who would ask questions about when violence was justified.
Adebolajo had a Muslim name, Mujaahid, which means one who engages in jihad. He went to meetings of the now banned Islamist organisation from around 2004 to 2011, but stopped attending those meetings, and those of its successor organisations, two years ago.
The soldier’s murder is being treated as a terrorist incident. Thursday saw another meeting of the government crisis committee Cobra, chaired by Cameron. However, so far the national threat level from al-Qaida-inspired terrorism remains unchanged, suggesting that officials do not believe Britain faces a wave of similar attacks.
The immediate focus is on the criminal investigation, which on Thursday saw detectives from Scotland Yard’s counterterrorism command raid five addresses in London, and one in Lincolnshire that was the Adebolajo family home.
Sources stressed that the investigation was at an early stage, but detectives are examining whether the arrested woman was in a relationship with one of the two men detained on Wednesday, and what the links are between the four people they currently have in custody. The arrests are a clear signal that counterterrorism detectives suspect the attackers may not have acted alone.
Adebolajo’s mother moved her family out of London to Lincolnshire in an attempt to remove him from the influence of a street gang. But Michael Adebolajo returned to the capital to go to university. The 28-year-old was a regular volunteer at the al-Muhajiroun stall outside HSBC bank on Woolwich High Street, handing out extremist literature. One witness said he had been recently seen outside Plumstead community centre encouraging an audience to go to Syria to fight.
His family were churchgoing Christians of Nigerian heritage but he converted to Islam about 10 years ago and investigators are trying to establish how he became radicalised to the point that he may have committed violence.
• This article was amended on Friday 24 May 2013 to include updated information about the second suspect.
Vikram Dodd, Nick Hopkins, Nicholas Watt and Sandra Laville
The Guardian, Thursday 23 May 2013 21.22 BST
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