Salman Abedi, a 22-year-old Briton born to Libyan parents, detonated his bomb at Manchester Arena as parents arrived to collect their children at the closeman of a show by the U.S. pop singer in May 2017.
Among the dead were seven children, the youngest aged just eight, while 237 people were injured and 670 survivors reported suffering from psychological trauma.
Prosecutors had said his younger brother Hashem Abedi, now also 22, was just as guilty of the murders by helping his sibling to carry out the attack.
“Hashem Abedi encouraged and helped his brother knowing that Salman Abedi planned to commit an atrocity. He has blood on his hands even if he didn’t detonate the bomb,” Max Hill, Britain’s Director of Public Prosecutions said in a statement.
London’s Old Bailey court was told Abedi helped his brother get the components of the homemade bomb and that together they experimented with its construction, buying screws and nails to be used as shrapnel.
They stored and made the device at a separate address in Manchester and, shortly before they returned to Libya in mid-April 2017, they bought a car to be used to store the bomb-making equipment.
Hashem Abedi was in Libya when the attack took place and became the first suspect to be successfully extradited to Britain when he was sent back in July 2019.
Islamic State said it was responsible for the attack in the immediate aftermath of the bombing, but security services have always treated that claim with skepticism.
In 2018, British lawmakers concluded that the MI5 security service had missed potential opportunities to prevent the bombing.
The Abedi family emigrated to Britain during the rule of late Libyan leader Muammar Gaddafi, later moving from London to the Fallowfield area of south Manchester. Hashem Abedi was born in Manchester and the brothers’ parents returned to Libya after Gaddafi was toppled in 2011.