Salman Abedi murdered 22 people, including seven children, when he targeted an Ariana Grande concert at Manchester Arena.
Here is what we know about the bomber so far:
:: He was born in Manchester in 1994, the son of Libyan parents who fled the Gaddafi regime.
:: Between 2009 and 2011 he was a pupil of Burnage Academy for Boys, then attended Manchester College, leaving in 2013. He studied business and management at Salford University but dropped out of the course.
:: He is thought to have lived at a number of addresses in the city, including one in Wilbraham Road, where police made an arrest, and Elsmore Road, where police carried out a raid on Tuesday.
:: He travelled to Libya in 2011 during school holidays to join his father Ramadan in the fight against Gaddafi, a schoolfriend told Newsnight. The Libyan leader was overthrown that year.
:: Abedi's father, who was arrested on Wednesday in Tripoli, has denied being a member of the Libyan Islamic Fighting Group, a proscribed organisation, but said he supports them.
:: It had been suggested Abedi "most likely" travelled to Syria but Turkish officials reportedly said they have no record of him travelling to the war-torn country.
:: He had been reported to authorities two years ago for expressing extremist views, a member of the Manchester-based Ramadhan Foundation said. He is believed to have been banned from Didsbury Mosque after challenging an imam who gave a sermon criticising the Islamic State terror group.
:: Abedi moved back to Libya in April to join his parents, who confiscated his passport amid concerns about his behaviour, the Times reported.
:: He flew into Istanbul airport on May 18, and later travelled through Dusseldorf airport, according to Turkish and German officials. He is not thought to have left the terminals on either occasion on his route back to Manchester.
:: At 7pm on Monday, little more than three hours before the explosion, he is believed to have visited a city centre flat in Granby Row. Police raided the property, number 39 on the third floor, which had been advertised on rental site Airbnb. Traces of bomb components were found in the flat, the Times said.
:: On the day of the attack he made a final phone call to his mother, according to Libyan authorities. He urged her to: "Forgive me."
:: At 10.33pm, minutes after the concert's scheduled finish and as thousands of fans left the arena, Abedi blew himself up, killing 22 people and injuring scores more with a home-made device packed with nuts and bolts.
:: Abedi's brother Ismail was arrested in Manchester a day after the attack, and another brother Hashim was arrested in Libya on Wednesday.
:: Their sister Jomana told the Wall Street Journal she believed Salman Abedi may have "wanted revenge" for US-led strikes in the Middle East.