Concert’s bomber seen as acting alone

LONDON — The man who detonated explosives at a pop concert in Manchester, England, last week, killing 22 people and wounding dozens, mainly acted alone in the days leading up to the attack, British police said late Tuesday.

The sophisticated planning and execution of the attack initially led British authorities to believe that the assailant, Salman Abedi, had the support of a larger terrorist cell. That, in turn, led to fears that a bomb-maker and a network of people who provided support could still be at large, possibly preparing further attacks.

But as detectives moved forward in their investigation, they said that their reconstruction of the movements and actions of the 22-year-old bomber in the four days before the attack showed that he had acted mostly on his own. They did not, however, rule out the possibility that others had been involved.

So far, 16 people have been arrested in connection with the attack, though five of them have been released without charges.

“We still have a number of people in custody,” Detective Chief Superintendent Russ Jackson, who leads the counterterrorism unit for the country’s northwest, said in a statement. “We will be seeking to extend the custody of some of them as we work to understand what has gone on and whether Abedi was helped.”

More than 1,000 officers have been involved in the investigation, learning about Abedi’s actions through analysis of surveillance cameras, phone records and other interactions he had with people in the days before the attack. More than 300 pieces of digital equipment have been examined as part of the investigation, police said.

“With specialist support we also have a good understanding of the likely component parts of the bomb and where these came from,” Jackson said. “Our inquiries show Abedi himself made most of the purchases of the core components, and what is becoming apparent is that many of his movements and actions have been carried out alone during the four days from him landing in the country and committing this awful attack.”

But police also said they could not rule out the possibility that he was part of a wider network.

“It is vital that we make sure that he is not part of a wider network, and we cannot rule this out yet. There remain a number of things that concern us about his behaviour prior to the attack and those of his associates which we need to get to the bottom of,” Jackson said.

Abedi, a Manchester resident of Libyan descent, is believed to have visited Tripoli four days before the attack, and experts say it is likely that he received training there to build the device he used for the bombing.

Police said they were “especially keen” to figure out why Abedi repeatedly returned to the Wilmslow Road area of Manchester. They also released an image of Abedi wheeling a blue suitcase and appealed to the public for more information about the suitcase.

Over the weekend, the United Kingdom’s state of alert was downgraded from “critical” — the highest level — to “severe,” and armed soldiers were gradually being withdrawn from high-profile sites, including Downing Street and Buckingham Palace.

As the investigation continues, the American singer who was performing on the night of the attack, Ariana Grande, announced Tuesday that she would return to Manchester to participate Sunday in a benefit concert for the victims and their families, alongside performers including Justin Bieber, Coldplay, Katy Perry and Miley Cyrus.

“Our response to this violence must be to come closer together, to help each other, to love more, to sing louder and to live more kindly and generously than we did before,” Grande said in a statement.