All 12 people arrested in relation to the London Bridge terror outrage have been released without charge, as two of the attackers were named by Scotland Yard.
Police raided two addresses in east London on Sunday, in the wake of the van and knife rampage in which seven people were killed and 48 injured.
Khuram Shazad Butt, a 27-year-old British citizen born in Pakistan, and Rachid Redouane, who claimed to be Moroccan-Libyan, were named as attackers on Monday evening.
Assistant Commissioner Mark Rowley said Butt was known to the security services, but there was no evidence of "attack planning" by him.
The Met said that family liaison officers had been deployed to support the families of the victims killed in Saturday’s attack.
One person is still believed to be missing, the force said.
Specialist officers are working with victims’ families and the coroner to formally identify those who were killed.
The two killers both lived in Barking, east London, while police are working to identify the third accomplice.
Butt, who The Guardian said was also known as Abu Zaitun, was known neighbours by the nickname "Abs/z".
He was known to the police and MI5, and a member of public had reported him to an anti-terror hotline.
He is also alleged to have been an associate of radical hate preacher Anjem Choudary.
Mohammed Shafiq, chief executive of the Ramadhan Foundation, said Butt called him a "Murtad" - traitor in Arabic - when he confronted Choudary about his support of terrorism days after the murder of Lee Rigby in 2013.
The investigation into Butt began in 2015, Mr Rowley said, adding: "However, there was no intelligence to suggest that this attack was being planned and the investigation had been prioritised accordingly."
He was part of an investigation "prioritised in the lower echelons of our investigative work", Mr Rowley said.
Redouane, 30, also used the name Rachid Elkhdar, claiming to be six years younger.
Security sources in Ireland confirmed Redouane married a British woman in Dublin in 2012 and lived in Rathmines, Dublin.
It is not clear when he came to the Republic or how long he stayed but it is believed he used Irish jurisdiction to get a European Union permit which allowed him to be in the UK.
Redouane left Ireland after the wedding and may have travelled to Morocco before settling in the UK.
He returned to Ireland again in 2015, again for an unknown length of time, but Taoiseach Enda Kenny said he was not one of a small number of radicals under surveillance.
An Irish security source described the killer as having "extensive immigration history related to the UK".
It is not yet known how the two men knew each other, and work is continuing to understand more about the trio, their connections and whether they were assisted or supported by anyone.
Detectives would like to hear from anyone with information about the men, particularly places they may have frequented and their movements in the days and hours before the attack.
Scotland Yard Commissioner Cressida Dick said authorities were confronting a "new reality" after three deadly assaults hit the UK in 10 weeks.
The Islamic State terror group, also known as Daesh, has claimed the London Bridge rampage, while the attack has sparked fears Britain is in the grip of a spate of copycat incidents.
In the latest outrage, three terrorists killed seven victims and injured dozens more in the London Bridge area on Saturday night.
Pedestrians were struck by a van on London Bridge before attackers stabbed a police officer and revellers around Borough Market with 12in knives.
Hundreds sheltered in pubs and restaurants, barricading themselves inside as the terrorists stalked the street.
The attackers, wearing fake suicide vests, were shot dead by eight officers after police opened fire with a hail of 50 bullets.
Tales of heroism emerged, with one British Transport Police officer taking on the attackers armed only with his baton before being stabbed in the head, face and leg.
Three other officers were hurt in the attack.
Of the 48 people taken to hospital, 36 are being cared for in London hospitals with 18 in a critical condition.
Police raided a number of properties in Barking and Newham in the days after.
On Monday evening, a crowd of all ages and races stood quietly for an impeccably observed minute’s silence at a vigil a short walk away from the scene of Saturday’s bloodshed.
London mayor Sadiq Khan warned extremists they will never win as mourners gathered at the service in Potters Fields Park, near London’s City Hall.