Police in Manchester, England, released a photo Monday of suspected suicide bomber Salman Abedi just days before the May 22 attack at an Ariana Grande concert.
In the photo, Abedi is seen with a hard blue suitcase, which authorities say he had with him when he visited the Wilmslow Road area and Manchester's city center between May 18 and May 22.
Police are asking for the public's help locating the suitcase, which they say is a "different item" than the one Abedi used in the attack.
"We have no reason to believe the case and its contents contain anything dangerous but would ask people to be cautious," said Det. Chief Superintendent Russ Jackson.
The bombing investigation expanded Monday when police arrested a 23-year-old man on suspicion of terrorism, hundreds of miles south of Manchester.
So far, 14 men are being held on suspicion of violating the Terrorism Act. They have yet to be identified or charged.
Police are still scouring through 12,960 hours of closed circuit TV recordings, searching for clues and collecting pieces of evidence.
Britain's top counterterrorism police officer, Assistant Commissioner Mark Rowley, told reporters Friday that authorities have already shut down a large part of Abedi's alleged network.
The Associated Press contributed to this report.