Salman Abedi carried out a deadly suicide bombing at a Manchester pop concert just days after returning from Libya, according to reports.
The 22-year-old's visit to his family's native country fuelled concerns he was preparing for Monday's assault in Britain under the guidance of hardened jihadists.
The Times reported the Manchester-born bomber spent three weeks in the war-torn north African nation before the attack on Manchester Arena, in which he was killed.
A friend told the paper: "He went to Libya three weeks ago and came back recently, like days ago."
Islamic State, who claimed responsibility for the attack, and al-Qaeda have a presence in Libya, but Abedi might have travelled to their heartland in Syria for training.
Prime Minister Theresa May said it was possible he had planned his attack, which killed 22 people and injured 59, with a "wider group of individuals".
Born and raised in Manchester, Abedi grew up in a Muslim household but matured into a university dropout with an appetite for bloodshed.
He was registered as recently as 2016 as living at Elsmore Road, where police raided a downstairs semi-detached property on Tuesday.
Neighbours recalled an abrasive, tall, skinny young man who was little known in the neighbourhood, and often seen in traditional Islamic clothing.
He is thought to have lived at a number of addresses in the area, including one in Wilbraham Road, where plain-clothes police made an arrest on Tuesday.
Abedi previously lived with his mother, Samia Tabbal, father Ramadan Abedi and a brother, Ismail Abedi, who was born in Westminster in 1993.
He is thought to have a younger brother, Hashim Abedi, and a sister, Jomana, whose Facebook profile suggests she is from Tripoli and lives in Manchester.
A family friend, who asked not to be named, said they were known to the city's Libyan community and described Abedi as "normal".
"He was always friendly, nothing to suggest (he was violent). He was normal, to be honest," he said.
Abedi is believed to have attended the Manchester Islamic Centre.
There, he reportedly caught the attention of one imam whom he stared down during a sermon denouncing terrorism.
"Salman showed me a face of hate after that sermon," Mohammed Saeed told The Guardian of the 2015 encounter.
Abedi studied business and management at Salford University two or three years ago, a source said, but did not complete his degree.
