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 this week.
Eleven people remain in custody for questioning following a series of raids across the country as three men - two aged 20 and 24 from the Fallowfield area and a 37-year-old from Blackley - were released without charge on Tuesday.
Manchester suicide bomber Salman Abedi likely purchased most of the key bomb components himself and many of his actions were carried out alone, according to British police investigating the attack.
A total of 16 people have been arrested in connection with the investigation.
Greater Manchester Police are treating the explosion as a terrorist attack and have confirmed 22 fatalities and 59 injured.
Born in Britain to Libyan parents, Abedi is believed to have returned from a trip to Libya a few days before the bombing.
Officers were still trying to determine whether Abedi was part of a wider network, which could not be ruled out yet.
Police have been attempting to retrace Abedi's movements ahead of the attack by examining CCTV footage and reviewing his phone calls.More news: Russian Federation investigation: US Congress issues subpoenas
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Updating the "huge progress" made in the inquiry, Detective Chief Superintendent Russ Jackson, head of the North West counter terrorism unit, said: "Much of the investigation has been painstakingly working through Salman Abedi's last movements".
Although detectives have no reason to believe the luggage contains anything risky, they are warning the public not to approach it and instead call 999 immediately. They have not been identified or charged.
"What we still need to understand is if he had any of the bomb parts in his possession before he went out of the country, this is why we are tracking his movements so carefully".
Calling the scale of the investigation "enormous", Jackson said there are more than 7,000 entries listed on the counterterrorism unit's lines of inquiry.
"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".
Police still have almost 300 pieces of digital equipment, including phones, to examine as well as hundreds of witnesses to interview, according to Jackson.
Police had previously searched the property in Rusholme's Curry Mile on Monday.