There were “missed opportunities” to identify Salman Abedi as a suicide bomber before he killed 22 people at Manchester Arena, a public inquiry has heard.
Abedi, 22, was reported to police and security as acting suspiciously in the minutes before he detonated his bomb, the inquiry into the terror attack heard, but no action was taken.
A member of the public had spotted Abedi wearing a large backpack and thought he was praying less than an hour before he detonated his bomb at 10.31pm.
Another person spoke to a British Transport Police (BTP) officer about Abedi, the inquiry was told.
On the first day of inquiry into the events of May 22, 2017, Paul Greaney QC, counsel to the inquiry, said experts had been asked to look into the security at the arena that night.
Mr Greaney said that “of considerable importance, the experts consider, on the basis of the information currently available to them, that, on May 22, there were missed opportunities to identify Salman Abedi as a threat and take mitigating action.”
He said that the experts concluded: “If the presence of a potential suicide bomber had been reported, it is very likely that mitigating actions would’ve been taken that could have reduced the impact of the attack.
“This is because there was sufficient time between Abedi first being spotted by, and also reported to (security) staff and his attack to effectively react.”
Mr Greaney added: “The evidence about these potential missed opportunities will need to be considered with the greatest possible care.”
He said whether there were “missed opportunities” to prevent the attack or reduce its deadly impact would be a key consideration for the inquiry, which began on Monday.
Loved ones of the 22 people who died in the bombing stood in silent remembrance as the names of the victims were recited by Mr Greaney at the opening of the hearings.
Sir John Saunders, a retired High Court judge, is leading the probe examining events before, during and after the attack at the end of an Ariana Grande concert.
Abedi, surrounded by a throng of elated youngsters leaving the show, exploded his shrapnel-packed rucksack bomb, sending thousands of nuts and bolts shredding everything in their path.
Summarising the evidence at the beginning of the inquiry process, Mr Greaney described how William Drysdale spotted Abedi in the City Room of the arena and a second witness with Mr Drysdale then approached a British Transport Police (BTP) officer.
Two more witnesses, known only as A and B, a couple who had taken their daughter to the concert, also saw a man matching Abedi’s description acting suspiciously.
Mr A spoke to a Mohammed Agha, an employee of Showsec, the firm which provided security to the Arena on behalf of the venue’s owners, SMG.
The witness made the report to Mr Agha at 10.14pm, some 17 minutes before the detonation. Mr Agha then spoke to a colleague, Kyle Lawler, about the matter, eight minutes before the bomb went off.
But neither security control, nor anyone else, was informed about the suspicious activity, the hearing was told.
A witness, Julie Merchant, approached BTP officer Jessica Bullough, around 32 minutes before the deadly bombing, to point out Abedi.
Mr Greaney said Ms Merchant cannot recall the details of the conversation with the officer but that it was “to do with praying and political correctness”.
The officer cannot remember the conversation taking place, the hearing was told.
She was the first police officer to enter the City Rooms after the bombing, showing considerable bravery, Mr Greaney added.
Earlier, formally opening the inquiry, Sir John said: “This is an exercise in establishing the truth. If I conclude things went wrong then I shall say so, but we are not looking for scapegoats. We are searching for the truth.
“The explosion killed 22 people, including children, the youngest was eight years old.
“Salman Abedi blew himself up in the explosion but he intended as many people as possible would die with him.”
Sir John said some evidence must be heard in secret to prevent further similar terrorist attacks.
Abedi was known to the security services, and a senior MI5 officer, known only as witness J, is expected to give evidence to the inquiry later this year.
The bomber’s brother, Hashem Abedi, now 23, was last month jailed for life with a minimum 55 years before parole, for his part in the deadly bomb plot, which left hundreds of other people injured.
Some evidence, involving information judged to be potentially of use to terrorists, is subject to restriction orders, and those hearings will be closed to the public.
The most sensitive evidence is likely to be heard at closed hearings, with both press and public excluded because of the risk to national security.