Yahoo News Timeline: Manchester bomber was on MI5's radar more than 20 times
The Manchester Arena bomber was on MI5's radar more than 20 times - including for attempts to travel to Syria and his links to Islamic State fundraisers.
An inquiry into the atrocity found the security service might have been able to prevent the attack.
Former high court judge Sir John Saunders delivered his third and final report from the inquiry on Thursday, after hearing evidence from the intelligence community - prompting a furious response from the families of the victims and an apology from MI5.
A total of 22 people died, with hundreds more injured, in the terrorist attack on 22 May 2017.
The timeline below sets out the number of times the bomber was on MI5's radar.
Read more:
Step by step - the security failings on the night in detail
December 2010
Salman Abedi first came to MI5's attention seven years before the attack, when an address linked to him was relevant in one of its investigations.
2011
The following year, MI5 and counter-terrorism police made checks after information was received that Abedi may be travelling to Syria. It was determined he had gone to Europe briefly.
3 and 17 November 2011
Ramadan Abedi, Salman's father, was subject to a Schedule 7 ports examination at Manchester Airport and Dover, returning from Libya. On one occasion Salman was with him.
December 2013
MI5's Operation Camellia investigated a man suspected of planning to go to Syria to join the fighting.
It looked at whether Abedi matched the profile of an individual seen acting suspiciously alongside their subject of interest, but he was ruled out.
18 March 2014
MI5 made Abedi a subject of interest in his own right, opening an investigation because a telephone number registered to him had been in contact with Operation Camellia's subject of interest.
He was treated as a "Tier Three" contact - someone who was not involved in the main activity - and his case was closed four months later.
8 July 2014
Salman and his younger brother, Hashem Abedi, travelled to Libya.
On 4 August, the Royal Navy's HMS Enterprise evacuated 110 Britons from the war in Tripoli.
Among them was Abedi, then 19, and Hashem, then 17. Neither the Ministry of Defence nor the police conducted a debriefing with them.
1 August 2014
IS recruiter Abdalraouf Abdallah's home was searched and his phones seized as part of Operation Oliban, revealing 1,300 texts with a person called "Salman", including some in praise of martyrdom.
Read more:
'Blood on their hands' - Could MI5 have stopped attack?
'Am I going to die?' The emergency services' response
2015
Abedi appeared again in an MI5 investigation in 2015.
His phone number was in contact with "Subject of Interest B", an individual previously linked to al Qaeda and under investigation at the time for facilitating travel to Syria.
The same number was already in MI5's file because the alleged extremist in Operation Camellia had saved it on his phone as "Salman in Manchester".
MI5 knew at this point that Abedi and Subject of Interest B had met in person a number of times.
Also in 2015, MI5 received information that Abedi was in contact with a "longstanding" subject of interest, described as "Subject of Interest C", who had previous affiliations with a group in Libya.
February 2015
Abedi visited IS recruiter Abdallah when he was on remand in Belmarsh prison in London.
MI5 and the North West Counter Terrorism Unit sought information on the nature of the visit but did not get any intelligence which they felt justified looking into Abedi as a formal subject of interest.
6 May 2015
A letter to counter-terrorism police by an MI5 officer indicated an investigative team were considering opening a "lead" investigation into Abedi and another individual.
No such investigation was opened but for more than a year between June 2015 and August 2016, as part of another lead investigation, intelligence was received on Abedi.
He was "effectively being treated as a Tier 2" subject of interest - one involved in funding or travel abroad - although not "formally" being a subject of interest.
On several occasions, Abedi was "mentioned in reporting" to MI5, which included "conflicting information" about his support for IS.
3 September 2015
Salman's older brother, Ismail Abedi, was subject to a Schedule 7 ports examination at Heathrow as he returned from his honeymoon in Malaysia. Radical material was found on his phone.
16 September 2015
Salman Abedi and Hashem Abedi travelled to Saudi Arabia for the Hajj pilgrimage, returning on 3 October.
Friends later say this was a turning point for Hashem, who was to become his brother's bomb-maker.
October 2015
Abedi was reopened and closed as a subject of interest on the same day.
He was thought to have had direct links to a "senior" Islamic State figure in Libya, but the case was closed when it was clarified their links were through a third person.
7 November 2015
Salman Abedi travelled to Germany via Paris. He returned to Britain the following day.
Initially, an MI5 officer considered it was likely he was attempting to travel to Syria but an MI5 investigator - in conjunction with colleagues - disagreed and concluded travel to Syria was unlikely.
Separately, the Paris attacks took place six days later.
April 2016
Abedi appeared as a "second level" contact, meaning the contact of a contact, for an MI5 subject of interest who was under investigation for providing financial support to a member of IS in Syria.
May 2016
A month later, MI5 made checks after Manchester Airport informed police that Abedi was seen activating a boarding card next to a suspicious individual, thought to be the IS recruiter Abdallah.
It turned out not to be Abdallah and while the pair travelled to Istanbul, a well-known transit point to Syria, they were actually on their way to Libya.
Early 2017
On two occasions, intelligence was received by MI5 about Abedi that was assessed to relate to "possibly innocent activity or to non-terrorist criminality on his part".
Its nature has never been publicly disclosed due to national security, but the inquiry found that had the intelligence been interpreted differently, Abedi may have been thwarted.
Neither piece of intelligence was shared by MI5 with counter-terror police in the North West.
January 2017
Abedi, aged 22, again appeared as a second-level contact of an individual who was being investigated because he had previously travelled to Syria and was linked to IS.
18 January 2017
Abedi visited Abdallah in prison again, this time at HMP Altcourse, accompanied by two associates.
The three men were together in the visitors' hall for an hour and 47 minutes. The date was significant because it was the day Abedi ordered his first bomb-making chemicals.
MI5 was informed of the visit.
3 March 2017
Abedi was flagged as a potential terrorist by a computer programme, as a result of intelligence received in mid-2016.
He was one of 685 subjects of interest to hit a "priority indicator" for his case to be reopened.
On 1 May, three weeks before the attack, MI5 triaged Abedi's case and decided it met the criteria for further investigation.
April 2017
Abedi was again flagged up as a second-level contact of a subject under investigation for links to a recruiter and facilitator for IS in Libya.
8 May 2017
Abedi was one of 26 people referred to another security service operation, looking at whether people had re-engaged with extremism.
A meeting to discuss the case was due to be held on 31 May, nine days after the attack.
The atrocity and aftermath
22 May 2017
Salman Abedi committed mass murder when he detonated his homemade bomb filled with shrapnel while people left an Ariana Grande concert.
Twenty-two innocent people were killed and hundreds were injured.
20 August 2020
The attacker's brother, Hashem Abedi, was sentenced to at least 55 years after being found guilty five months earlier of 22 counts of murder.
The court heard how he helped source, buy, stockpile and transport components for the bomb, using a number of phones, vehicles and addresses.
