The suicide bomber who killed 22 people and injured dozens more at the Manchester Arena has been named as 22-year-old Salman Abedi.
Born in Manchester in 1994, the second youngest of four children, his parents were Libyan refugees who came to the UK to escape the Gaddafi regime.
His parents were born in Libya but appear to have emigrated to London before moving to the Fallowfield area of south Manchester where they lived for at least 10 years.
They had three sons and a daughter, who is now 18 years old.
Abedi grew up in Whalley Range, just metres from the girls' high school that hit the headlines in 2015 when twins and grade A pupils, Zahra and Salma Halane, who were aspiring medical students, left their homes and moved to Isis-controlled Syria.
There were unconfirmed reports in Manchester that the whole family, apart from the two elder sons, recently returned to Libya.
Abedi was named by Greater Manchester Chief Constable Ian Hopkins yesterday.
"Can I start by once again passing on our heartfelt sympathies to all the innocent people caught up in last night's despicable act.
"We now have a team of specially trained family liaison officers who are supporting families.
"There has been much speculation and names of those who may have been killed in the media and social media. We accept that this is inevitable, however, we ask that people allow the police and coroner to release the names once the families are ready and appropriately supported.
"As you would expect the police response to this across Greater Manchester has been significant as we support people to go about their daily business.
"Part of this response has seen us arrest a 23-year-old man in connection with the attack and we have also carried out two warrants, one in Whalley Range and one in Fallowfield that included a controlled explosion to enable safe entry.
"We understand that feelings are very raw right now and people are bound to be looking for answers. However, now, more than ever, it is vital that our diverse communities in Greater Manchester stand together and do not tolerate hate.
"We have been visited by the Prime Minister and Home Secretary and we have taken them through the emergency response so far and what we plan to do in future days.
"I can confirm that the man suspected of carrying out last night's atrocity has been named as 22-year-old Salman Abedi. However, he has not yet been formally identified and I wouldn't wish, therefore, to comment further.
"The priority remains to establish whether he was acting alone or as part of a network."
As with the Westminster atrocity in March, the most pressing question is whether Abedi was a so-called "lone wolf" or part of a wider terror cell.
On Tuesday, it was reported that the Islamic State group had claimed responsibility for the attack.
Although the working theory is that the perpetrator triggered the blast alone, the national police counter-terror network, assisted by MI5, is urgently piecing together his background to see whether he had any help in planning the outrage.
They will be looking to build a picture of the attacker's movements in recent weeks and months as well as immediately before the strike.
Another priority will be to establish whether any further linked attacks or copycat acts are planned.
It is likely that the bomber's communications will form a significant part of the inquiry, and investigators will also be checking if he was known to authorities in any way.
One area of focus will be examining the remnants of the device used in the attack as officers work to establish whether the perpetrator built it himself or had help.
As well as seeking to identify any potential accomplices in Britain, authorities will also be looking into the possibility of any link to international groups.
In the first hours after an attack on this scale investigators were sifting through a number of theories as they work to settle on the most likely lines of inquiry.
The official threat level from international terrorism stands at severe in the UK - indicating that an attack is "highly likely". It has stood at this level - the second highest of five - since August 2014.
There has so far been no indication that this will change in the wake of the events in Manchester.
Shashank Joshi, senior research fellow at security think tank the Royal United Services Institute, said: "The most important point is that police have found the body of what they believe to be the lone suicide attacker.
"If they have identified him, they will be able to begin establishing his movements, his contacts, and his background.
"This, in turn, will help establish whether he acted alone, in concert with a small number of other conspirators, or as part of a larger network.
"The method of attack is likely to downgrade the likelihood that this was perpetrated by a far-right individual or group, as they have not typically used suicide bombers.
"We know that both al Qaeda and Islamic State seek to conduct attacks in the UK, and that the UK's terror threat level has been at 'severe' for three years."
Commentators also pointed out that the Manchester attack took place on the fourth anniversary of the killing of Fusilier Lee Rigby in Woolwich, southeast London.
Former head of the National Counter Terrorism Security Office, Chris Phillips, told BBC Radio Four's Today programme that the date may also be significant.
Meanwhile, Greater Manchester Police have confirmed a 22-year-old man has been arrested in connection with the attack.
Bomber behaved strangely before attack
Neighbours of British-born Manchester suicide bomber Salman Abedi have revealed the Manchester United fan's "strange behaviour" in the weeks before he slaughtered 22 people.
The 22-year-old Manchester-born attacker was heard "chanting Islamic prayers loudly in the street" outside his home in the south of the city.
Abedi is the third of four children of Libyan refugees who came to the UK to escape the Gaddafi regime. They are believed to have lived in the Fallowfield area of south Manchester for at least 10 years.
One neighbour claimed to have heard Abedi chanting Islamic prayers at the home just weeks before the concert hall atrocity.
Forensic officers were seen emerging from the property carrying a booklet called Know Your Chemicals.
Lina Ahmed, 21, told MailOnline: "They are a Libyan family and they have been acting strangely.
"A couple of months ago he [Salman] was chanting the first kalma [Islamic prayer] really loudly in the street. He was chanting in Arabic.
"He was saying 'There is only one God and the prophet Mohammed is his messenger'."
Abedi's former school friend Leon Hall told MailOnline he saw the killer last year and said he had grown a beard.
He also said the jihadist was a keen Manchester United fan.
Hall, 26, and Abedi lived close to each other as children in a row of run-down terraced houses in Manchester's Moss Side.
They later ended up living next door to each other in a nearby street and went to the same school.
Hall said: "I saw him last year and he had a beard thing going on. We didn't speak but just nodded to each other. I don't remember seeing him with beard before."
Hall said they grew up playing together on the street around their home.
"He and I had a tussle many years ago when we were kids. It was over nothing, but he always had a bit of an attitude problem. I can't say I really liked the man."
Hall, who was sitting outside his home with his sister, said Abedi was a Muslim.
Other family members at the house, who asked not to be named, confirmed that Abedi was a Muslim.
Abedi, who lived in a housing association owned home about 3km from Monday night's terror attack.
He later moved about 360m away to another terraced home. Many of the terraced homes house newly arrived immigrants.
Officers are combing CCTV to determine whether the attacker carried out a "recce" of the arena before detonating a nail bomb as thousands were leaving the concert.
The suicide attacker is said to have been "known" to the authorities and anti-terrorist officers are going through hundreds of hours of CCTV footage trying to "pick him up" during his journey to the arena.
Officers believe he will have checked out the giant venue in recent days and a separate team are studying footage going back into the past week.
- Daily Telegraph, Daily Mail