'A-19-year-old man was arrested at Liverpool John Lennon Airport on Friday 7 July 2017.
Several properties have previously been raided as part of the probe into the attack, with an address in St Helens initially targeted by counter-terrorism chiefs.
"We don't have evidence of a large network".
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The training mission occurred the day before President Trump and Chinese President Xi met at the G-20 summit in Germany. Such actions, however, may do little to sway China or deter it from boosting its military presence in the region.
Detectives want to question Abedi's younger brother Hashem, who has been detained in Libya, and are "engaging with" British prosecutors and Libyan authorities, Jackson said.
It comes a day after detectives said they believed the bomber did not act alone when preparing the deadliest attack on United Kingdom soil since the 7/7 bombings exactly 12 years ago. "We do however suspect others were either aware or complicit in the knowledge of this attack".
Salman Abedi, a Briton of Libyan heritage, detonated a homemade knapsack bomb as crowds were leaving Manchester Arena on May 22, killing 22 people and himself.
Ali Mohamed, visiting a friend at a house across the road, said: "I saw Salman Abedi here".
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The other tidbit released is that there will be a special Anniversary Box available to purchase in-store. Of the 48 percent of respondents who heard "nothing at all", 9 percent downloaded the game.
Officer Russ Jackson said at a briefing Thursday: "We do believe that there are other people potentially involved in this".
He did not rule out further arrests.
Analysts have also searched through three million files and 16,000 hours of footage as they piece together his movements in the days and weeks prior to the attack.
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The Education Department did not immediately respond to a request for comment. But DeVos announced in June that she would delay its implementation.