The Metropolitan Police have defended a decision to downgrade an inquiry into one of the men who carried out Saturday night's terror attack.
They said Pakistan-born Khuram Butt, 27, of Barking, London, was known to police and MI5 in 2015, but there had been no evidence of a plot.
The two other perpetrators were not known to security services.
All 12 people arrested on Sunday after the London attack have now been released without charge.
Two of the three men behind the attack, in which seven people were killed and 48 injured have been named by police.
The other attacker was Rachid Redouane, 30, from Barking, who police said had claimed to be Moroccan-Libyan. He was a chef, who also used the name Rachid Elkhdar.
All three men were shot dead by police within eight minutes.
The attackers drove a hired van into pedestrians on London Bridge before stabbing people in the area around Borough Market.
