British Army soldier, Fusilier Lee Rigby.
The Intelligence and Security Committee was scathing about the failure to do so, saying the information could have saved the 25-year-old soldier's life. But Adebowale and fellow Muslim convert Michael Adebolajo had already been on the radar of MI5 and the police for years by the time they committed their savage murder. And in that time, the ISC report charted, a number of mistakes had been made by MI5 as well as the police and MI6.
Adebolajo came to the notice of the security service in 2008 when he was thought to have acquired equipment for a terrorist attack and held meetings with a member of al-Qaeda. A desk officer recommended that data should be acquired from his telephone, his digital footprint established and his home address found. None of these recommendations were carried out. No action was taken either over his links to Al Muhajiroun, a proscribed organisation.
Two years later, at a time he had been assessed to have been of only low-level interest, Adebolajo was arrested by police in Kenya as he was trying to cross into Somalia to join the Islamist group al-Shabaab. Neither MI6 - otherwise known as the Secret Intelligence Service or SIS - or MI5 were aware that he had travelled to east Africa, and MI6's subsequent inaction led to strong criticism from the ISC.
Adebolajo was to claim that MI5 had begun to harass him while trying to recruit him as an informant. Members of his family and friends say this tipped him over the edge into murderous violence. The ISC report did not deal with the recruitment issue in the report on "security grounds". On the allegation of harassment, it maintained: "We have investigated all aspects of MI5's actions thoroughly and have not seen any evidence of wrongdoing by MI5 in this area."
But while MI5 were trying to "turn" Adebolajo, they had not kept track of the people he had been seeking abroad. The failure to follow up on the 2008 recommendation to monitor his communications meant they failed to monitor his developing links with two Aqap members. One of them - a "Tier 1 Subject of Interest" codenamed SOI CHARLIE - may, according to reports in Islamist circles, have been Ahmed al-Awlaki, the American-born "Bin Laden of the internet" who was eventually killed in a Drone strike after an intensive hunt by the CIA.
The ISC said: "It was a mistake on MI5's part not to seek the content of Adebolajo's 2008 communication with an individual of interest who later became a high-profile and senior Aqap extremist." However, it accepted MI5's own assessment that "it would not have had an impact on the case".
Michael Adebowale came to MI5's attention in 2012, partly through his interest in the jihadist online magazine Inspire, which al-Awlaki had helped to found. In time he too had contacted SOI CHARLIE, Adebolajo's online al-Qaeda contact.
GCHQ tracked the connection but failed to pass this on to MI5. As a result the extent of the risk being posed by Adebowale was not logged and his link, through al-Qaeda, with Adebolajo was not noted.
6 details revealed
1 "Let's kill a soldier": internet conversations
Michael Adebowale had an internet account that urged violence against the military, but the account was not spotted until a week after the attack. He also had online conversations with a suspected al-Qaeda extremist but these were not found by MI5.
2 Internet firms failed to report extremist activities
Internet and social media companies failed to report findings. Accounts under Adebowale's name were closed for suspected terror activities - but this action was not shared with security officials.
3 MI5 and SIS's procedures were at fault
The report noted long delays between identification of a concern and action upon it. Some suggested actions were not carried out.
4 SIS's apparent lack of interest in Adebolajo's arrest
Despite Michael Adebolajo's arrest by anti-terrorist police in Kenya in 2011, SIS failed to take an interest after April 2013 when intensive surveillance on him was stopped.
5 SIS and police provided "conflicting accounts"
There was a breakdown in communication between police and security services.
6 No systems to deal with individuals on periphery
The two men appeared on the periphery of seven agency investigations as low-level suspects. There appears to be no strategy in dealing with such individuals.
