Manchester bombing suspect purchased most of the components himself, police say

— -- The man who allegedly detonated a bomb inside a crowded concert hall in Manchester last week purchased most of the parts used to construct the explosive device himself and appears to have done so alone, according to U.K. investigators.

Greater Manchester Police Detective Chief Superintendent Russ Jackson said investigators have been examining Salman Abedi's last movements and interactions to determine whether he acted alone in Britain's deadliest terrorist attack in more than a decade. So far, police have found that he worked mostly alone in the four days before the suicide bombing.

"Much of the investigation has been painstakingly working through Salman Abedi's last movements," Jackson said in a statement late Tuesday. "With specialist support, we also have a good understanding of the likely component parts of the bomb and where these came from. 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."

Abedi, a 22-year-old British-born man of Libyan descent, allegedly detonated a device minutes after American singer Ariana Grande finished performing at Manchester Arena on May 22. The attack killed 22 people, including children and teenagers, and more than 100 others were wounded. Abedi also died in the explosion, officials said.

According to the Greater Manchester Police, 11 men remain in custody as police investigate their possible connections to the attack. Five other people, including a woman, have been questioned and released without charge. Police have not identified or charged the arrested individuals.

Jackson, who heads the Greater Manchester Police's North West Counter Terrorism Unit, said it remains unclear whether Abedi was part of a greater terrorist 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 behavior prior to the attack and those of his associates, which we need to get to the bottom of," he said in a statement late Tuesday. "We still have a number of people in custody, and 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."

Jackson said investigators are particularly interested in Abedi's travels to the Wilmslow Road area in Manchester and a blue suitcase he took with him on those trips. Jackson had said the suitcase is a "different item" from the one Abedi allegedly used in the bombing, but police believe he was in possession of it "days before the attack."

Police still have nearly 300 pieces of digital equipment, including phones, to examine as well as hundreds of witnesses to interview, according to Jackson.

"We have had over 1,000 officers working on this investigation to piece together what happened and to understand if others have been involved," he said in the statement late Tuesday. "The scale of the investigation is enormous."

Police said Wednesday that a cordon has been placed around a property in Rusholme, south of central Manchester, where they are searching for clues about the bombing.