Bomber Salman Abedi was described by former school friends yesterday as being a vodka-drinking, pot-smoking teenager who was prone to lashing out.
Teased at school and nicknamed Dumbo for his big ears, Abedi confessed to "anger-management issues" after he punched a girl in the face, according to Daily Mail.
He struggled with his studies and later dropped out of university.
But the moment he truly started going off the rails, friends say, was when his father Ramadan Abedi moved back to Libya in 2011 to join the rebels fighting Colonel Gaddafi following the Arab Spring.
Mr Abedi and his wife Samia Tabbal - an engineer who graduated top of her class from Tripoli university - had fled the dictator's regime in 1993, and were allowed into Britain as political refugees.
Abedi and his three siblings were born here, with the family moving to London, then Manchester.
But they seemed to shun British culture, with classmates remembering Abedi's poor English.
A family friend said: "According to people that know Salman, he's not very sharp, he's slightly sub-normal in terms of his IQ.
"But his father is a good man. I don't think he's involved or knows about this at all because he definitely would have prevented it."
Photos show Abedi as an ordinary, happy teenager, lounging on the beach with friends in Libya during a visit when he was 14 or 15, and hanging out with his mates near the family's red-brick terraced house in south Manchester.
But Abedi's dark side emerged when drunk, said friends. One who knew him for seven years said: 'He would drink - it was mainly vodka - and smoke weed.
"He was always clubbing or at house parties. He was always popular with women at the parties. He was confident, so he always had girls around him. He loved rap and grime and house.
"He used to get into trouble quite a lot because he would get into fights. He was like a typical street person.
"We were on a night out in Liverpool last year when somebody barged into him and he just started going mental and punched him."
Another friend added: "He's not ordinary when it comes to getting his aggression out.
"He would have fights for no reason. Two years ago we were in the park together playing football, when two random guys were walking past, minding their own business and chatting. Salman just randomly walked over to them and started punching them.
"He was a bit weird, he had a split personality. One minute he's OK and one minute he's fighting, getting aggressive.
"He was a bit mental.
"But he was also a bit of a gentleman when he wanted to be. He always used to walk his female friends home after a night out."
Abedi, 22, was born in Manchester on New Year's Eve 1994, and attended several schools.
At Wellacre Academy, an all-boys school in a leafy suburb, a former classmate recalled: "Salman was getting help from the people in learning-support.
"I don't know if he had something wrong with him. He came across like he had social problems. I think he was troubled. He used to wear glasses and be a bit goofy. There was a lot of bullying going on."
Between 2009 and 2011, he went to Burnage Academy, a boys' school catering largely to Manchester's Asian community, and was a keen footballer, often playing at Whalley Range High School where the Manchester United Foundation held training sessions.
A friend said: "Salman used to play a lot of football. He loved Manchester United and was actually pretty good."
It was during his final year at this school that, back in Libya, Colonel Gaddafi was ousted.
A neighbour said Abedi's father celebrated the despot's death by hoisting a massive flag on the roof of their housing association home in Fallowfield - until he was ordered to take it down.
After his father returned to Tripoli, Abedi became "traumatised, angry and unsettled", according to a neighbour.
The situation was not helped by some of the family's connections in Manchester, which included Gaddafi dissidents who had been members of the Libyan Islamic Fighting Group, which was linked to Al Qaeda.
Among them was Abd al-Baset Azzouz, later unmasked as a master bomb-maker.
Azzouz lived in Wilbraham Road at the same time as Abedi around the year 2000, and even after moving house was never more than a mile away.
Azzouz, 50, was identified by the US as one of the world's most dangerous terrorists after he set up a training camp in Libya and police are assessing whether Abedi was supplied with one of his bombs or was taught how to make one.
Father-of-four Azzouz, was arrested in the UK in 2006 by counterterrorism police but was later released on bail.
Counterterrorism officers are also to probe any links between Abedi and a cell of jihadists from Manchester who travelled to Syria in 2013 to join Islamic State.
One of the men, Anil Khalil Raoufi, grew up in the same neighbourhood as Abedi and was the same age as him. Raoufi died fighting for Islamic State in 2014.
Both Abedi and Raoufi had regularly attended Didsbury Mosque, although the mosque insisted that Raoufi, who travelled to Syria with a prolific recruiter for Islamic State, was radicalised online.
Again the recruiter, Raphael Hostey, was the same age as Abedi and grew up in the same area.
Abedi is also thought to have known Raphael Hostey, who recruited dozens of young Britons to fight for Islamic State in Syria before being killed in a drone strike a year ago.
Other one-time friends of the family are said to include several Libyans who went from Manchester to Syria, and Abu Anas al-Libi, a former Al Qaeda commander who was on the FBI's list of the world's most wanted terrorists.
A neighbour said abrasive, tall, skinny Abedi 'went off the rails' after his father left Britain.
His mother, sister and younger brother are also said to have moved to Libya last year.
"Salman suddenly had all this freedom and started partying loads. He would drink and go out all the time," said the source.
"In recent years he started growing a beard and being very judgmental.
"He would have a go at other Muslims for not being good."
At The Manchester College, which Abedi attended until 2013, he hung out with a gang of Libyans and Somalis, recalls a classmate who said Abedi once smashed a girl in the head in a rage because she wore a short skirt.
She said: "Salman would wear skinny jeans and a big blue Puffa jacket - the kind of things these gangster wannabes wear. He used to stand around and smoke with his friends. He said something rude about what the girl was wearing. The girl was really annoyed and slapped him.
"He came face to face with her and punched her really hard in the side of the head. He could have killed her. The headteacher sent him home. Apparently he told the head he had anger-management issues and needed help. He had said there was a lot of things going on with his family and his brothers were in Libya fighting."
Yesterday Abedi's older brother, Westminster-born Ismail, 23, was still in police custody after being arrested in Chorlton, Manchester, within hours of the bomb attack.
His maths teacher wife Salha, 23, a Briton of Libyan descent, is said to be pregnant.
A friend said: "The brothers couldn't be more dissimilar. Salman was a uni dropout, always smoking and drinking and a very free individual, easily influenced.
"His brother had a good job as a computer expert and had recently got married in Manchester.
"His wife's expecting their first baby and Salman was looking forward to becoming an uncle."
Ismail, who worked as a teaching assistant giving Arabic classes and IT support at Didsbury Mosque Quran School, was said to have been reported to the counter-terrorism unit after concerns were raised by members of the Muslim community.
Yesterday, their younger brother Hashem, 20, was also arrested in Libya - where he allegedly "confessed" that he and Abedi were members of Islamic State.
Abedi's sister Jomana, 18, is also thought to have worked at the Didsbury Mosque.
A model student, she was in the same year at the same school in Whalley Range that hit headlines in 2015 when 16-year-old twins Zahra and Salma Halane moved to Syria.
Their brother Ahmed Halane, 24, was at Burnage with Abedi. He is a terror suspect himself, banned from Britain under an exclusion order.
The company Abedi was keeping could hardly have been worse. Another of his friends, Bilal Ahmed, went to jail for gang-raping a 16-year-old girl.
In 2014, Abedi began a business management course at the University of Salford. But a spokesman said: "He turned up for lectures for two years and then just stopped coming."
Neighbour Lina Ahmed, 21, said Abedi began chanting Islamic prayers in the street, adding: "A couple of months ago he was chanting really loudly in the street. He was chanting in Arabic."
Another said: "He has had a beard and has been wearing robes rather than Western dress when I have seen him recently."
He said they had played football in a local park, adding: "I distinctly remember his eyes being glazed. It seemed like he had been smoking cannabis."
At the Didsbury Mosque, where Abedi's father used to perform the call to prayer, Imam Mohammed Saeed El-Saeiti had become wary of him.
Mr El-Saeiti said that when he gave a talk in 2015 warning of the dangers of IS, Abedi showed him 'the face of hate'.
Witness Akram Ramadan, 49, said Abedi had "stood up and started calling the imam, 'You are talking b*******'. He gave a good stare, a threatening stare, into the imam's eyes. He was banned."
Mr Ramadan believes the mosque reported him to the authorities for his extremist views.
Last night, US intelligence officials claimed Abedi's mother and friends of the family had also reported him, claiming he'd said "being a suicide bomber was OK".
Abedi began regularly visiting Libya, and Syria too, according to sources, with one saying he returned from Libya days ago.
On Monday, consumed with anger after a life of failure, he took a rucksack full of explosives and wrought carnage on the country that gave his parents a haven.