Police have released CCTV images of the Manchester Arena bomber as they continue to piece together his final movements.
Greater Manchester Police and Counter Terrorism Policing North West have been working closely with the national counter terrorism policing network on what they described as "a large scale and fast-moving investigation" since the attack on Monday.
They are now seeking information about what Salman Abedi - the man identified as the bomber - was doing in the days before the bombing.
In a joint statement, Greater Manchester Police's Chief Constable Ian Hopkins and Deputy Assistant Commissioner Neil Basu, senior national co-ordinator for UK Counter Terrorism Policing, said: "Today we are releasing an image of Salman Abedi taken from CCTV on the night he committed the attack.
"We are gathering a detailed picture of Abedi as the investigation develops and now need people to tell us if they have any information about his movements from 18 May when he returned to the UK through to Monday night.
"The investigation is making good progress and we know one of the last places Abedi went was the city centre flat and from there he left to make his way to the Manchester Arena. The flat is highly relevant as a location which we believe may be the final assembly place for the device."
They said Abedi was identified as the attacker within two hours of the bombing and detailed how the investigation had progressed.
They said: "We immediately established full command and control of the incident and within an hour of the attack taking place a specialist counter terrorism control room had been established with a first priority of identifying the attacker.
"Specialist counter terrorist forensic teams were sent to try and identify the attacker and within two hours his identity was known. With this information officers could begin to establish his movements to try and understand if anyone else was linked or any more attacks planned.
"Firearms officers from across the country were deployed to support Greater Manchester Police colleagues who were already deployed to the area in case of a further attack.
"We called in officers from around the national counter terrorism policing network and they quickly arrived from across the UK. By early Tuesday morning there was an established pattern with all officers and staff working on the response to the attack in day and night shifts of approximately 14 hours each."
The police are still searching 14 addresses, including a house on Springfield Street in Swinley where officers remained today.
Thirteen people have been arrested on suspicion of offences contrary to the Terrorism Act, including a 33-year-old man arrested on Upper Dicconson Street in Swinley on Wednesday.
In total 17 warrants have been carried out, mainly in Greater Manchester.
The men continued: "The whole team are working round-the-clock. We have around 1,000 people involved in the investigation alone. In addition there are hundreds of officers and staff from Greater Manchester Police and other forces involved in the security around Greater Manchester.
"In the past five days we have gathered significant information about Abedi, his associates, his finances, the places he had been, how the device was built and the wider conspiracy. As a result of the arrests and searches which have taken place we now have many further lines of enquiry. We already have more than 1,500 actions we are pursuing.
"This is still a live investigation which is not slowing down. Our priorities are to understand the run up to this terrible event and to understand if more people were involved in planning this attack."
Anyone with information is asked to call the anti-terrorist hotline in confidence on 0800 789321.
If you have any images or footage that you believe can assist police, they can be uploaded to Ukpoliceimageappeal.co.uk or Ukpoliceimageappeal.com.