Police have named the attackers as Khurum Butt, 27, who had been known for his extremist views; 30-year-old Rachid Redouane, also known as Rachid Elkhdar; and Youssef Zaghba, a 22-year-old Italian national of Moroccan descent who was reportedly working in a London restaurant.
Just hours earlier, Greater Manchester Police announced they had arrested two 20-year-olds in connection with the attack at Manchester Arena.
After that, Amato said, any time Zaghba was in Italy, he was always tracked by Italian intelligence officers.
He was investigated in 2015 but he was "prioritised in the lower echelons of our investigative work" and there was no evidence of "attack planning", police said.
Mimbo said Butt had grown a longer beard and worn traditional Islamic dress more often over the two years he had known him, but showed no sign of radicalization.
The attack, the third in Britain in three months involving suspects who had been on the radar of British authorities, has raised questions over the government's ability to protect Britain following cuts to police numbers in recent years.
German rock concert resumes after terrorism alert
The festival grounds were clear by 9:30 p.m., about a half hour after people were told that they were going to have to leave. The organisers of Rock am Ring said intensive searches have been carried out.
After a brief pause, election campaigning resumed on Monday, with security dominating the agenda ahead of Thursday's vote.
French President Emmanuel Macron later confirmed there had been a third French victim of the London attack.
Nathalie Cros Brohan, sister of Mr Thomas's girlfriend Christine Delcros, posted on Facebook on Wednesday morning that the family "fear the worst".
"We need to look at how the terror threat is evolving, the way that terrorism is breeding terrorism and the increased tempo of attacks".
"We're pushing the British authorities because, frankly, this isn't the kind of thing that can go on and on", Spanish Foreign Minister Alfonso Dastis told the news agency Efe earlier in the week, according to The Guardian.
Echeverria was last seen lying on the ground near London Bridge after he confronted the assailants with a skateboard.
With formal identification of the victims still ongoing, the sisters of the missing Spanish banker Ignacio Echeverría confirmed on Wednesday he was among those killed. His sister Isabel wrote on Facebook Wednesday: "My brother Ignacio tried to stop some terrorists and lost his life trying to save others". He was also taken into custody on "suspicion of the preparation of terrorist acts", police said. They have been identified as Candice Hedge of Brisbane, and Andrew Morrison of Darwin, who were both stabbed in the neck.