Manchester Police released new photos on Monday of the bomber with a blue suitcase taken days before he carried out the deadly attack at an Ariana Grande concert, urging the public to come forward with any information on the item.
The photo showed Salman Abedi with a "distinctive blue suitcase" that was taken between May 18 and the day of the bombing, according to police. Officials stressed that the suitcase was different from the item Abedi used in the attack.
"We have no reason to believe the case and its content contain anything dangerous, but would ask people to be cautious," Greater Manchester police said in an update, adding that anyone who might have seen him with it before the attack to call the confidential hotline.
Counter-terrorism squads are trying to re-create Salman Abedi's movements in the days before he detonated the bomb at Manchester arena, killing 22 people and injuring 119 others. Police believe Abedi had the suitcase with him at two locations in Manchester.
In total, 14 men are in custody in connection with the May 22 bombing. Police arrested a 23-year-old Monday in Shoreham-by-Sea in England, hundreds of miles south of Manchester. The man was arrested on suspicion of terrorism offenses and an address there was searched.
The suspects have not been identified or charged. All are being held on suspicion of violating the Terrorism Act.
Police and security services have said very little about the network believed to be behind suicide bomber Abedi, a Manchester native whose parents had moved to Britain from Libya. Abedi's elder brother Ismail is among the suspects being held in Britain, and a younger brother and Abedi's father have been detained in Libya.
Britain's intelligence services have launched an inquiry into how warnings about the 22-year-old Abedi's radical views were handled amid indications that vital warning signs were missed.
Police are scouring 12,960 hours of closed circuit TV recordings in their search for clues, have collected more than 630 pieces of evidence and have searched 21 addresses.
Authorities say Abedi returned to Britain from Libya on May 18, and likely completed assembling his bomb at a rented apartment in central Manchester.
Britain's official terror threat level was set at "critical" in the days after the attack but was downgraded Saturday to "severe." The country remains on high alert, however, as officials caution that some suspects who helped Abedi may still be at large.
The Associated Press contributed to this report.