Police have released the remaining people held for questioning over links with the Manchester Arena attacker as they said it remains unclear whether he acted alone to gather bomb parts.
Almost three weeks on from the suicide bombing which left 22 people dead and more than 200 injured, Greater Manchester Police have issued new images of Salman Abedi, the white Nissan Micra he used and a barrel stored inside the car.
The force also said officers are yet to speak to Abedi's brother Hashim, who has been detained by authorities in Libya along with their father Ramadan.
Hashim reportedly told Libyan counter-terror forces he knew his brother was planning something and that the 22-year-old was radicalised while living in the UK two years before his deadly attack.
The British-born extremist of Libyan descent is believed to have built the explosive alone before he detonated the device as concert-goers began leaving a show by US singer Ariana Grande at 10.31pm on May 22.
Detective Chief Superintendent Russ Jackson, the head of North West Counter Terrorism Policing, said: "We have tracked him buying nuts from a DIY store that were used for shrapnel as well as the tin which we believe the explosive was placed in. He has also been tracked going to and from the Banff Road area of Rusholme.
"It is in Rusholme where the white Micra was found and in it considerable evidence. The Micra contained materials for bomb making and Abedi is forensically linked to the car."
Abedi bought the car on April 13 two days before leaving the country, and officers believe bomb parts were stored in it before he returned from Libya on May 18, bought nuts and a tin container and assembled his deadly device.
"Our enquiries show that the assembly of the device is likely to have been by Abedi himself," Mr Jackson said.
"What is less clear is whether he acted alone in obtaining the materials for the device before he left the country on 15 April and whether others knew or were complicit in the storage of materials knowing what was being planned."
A total of 29 houses were searched and 22 people were arrested during the inquiry - all have now been released without charge.
Mr Jackson added: "Each of the 20 detained people have been interviewed many times and they have been questioned about their associations and contacts with Abedi.
"During the investigation, we have uncovered a number of suspicious purchases of materials by individuals which can be used to make explosives."
Abedi sought to transfer money out of the country in the days before the attack and it has taken time for detectives to understand the context of his contacts in the hours leading up to the bombing.
"We have identified contact with Abedi that occurred close to the attack time and in some cases the presence of people of interest to the inquiry in Manchester city centre on the evening of the attack," Mr Jackson said.
"Although this is not the case for every person, it is factors such as these that have led us to make arrests.
"Some of those arrested and now released have offered accounts which explain innocent contact with Abedi and we are, at this time, satisfied with these explanations."
Mr Jackson said his "massive" team was working to piece together Abedi's movements in "fine grain detail" and had a number of lines of inquiry they would "relentlessly pursue".