LONDON: The brother of Manchester Arena bomber Salman Abedi had previously been questioned by British counterterrorism authorities and had Daesh content saved on his phone, an inquiry into the 2017 attack has heard.

Counterterrorism officers found recruitment videos for the terrorist group on Ismail Abedi’s mobile phone, as well as photos on Facebook of him holding weapons in 2015, one of which showed him holding a machine gun with a Daesh logo.

Salman Abedi, 22, killed 22 people and injured hundreds more in the attack after an Ariana Grande concert at the Manchester Arena on May 22, 2017.

Families of the victims, who made statements at the inquiry on Monday, criticized the British intelligence agency MI5 for what they called “grave misgivings” and a failure to spot the risk Ismail posed, The Times newspaper reported.

John Cooper, a judge acting for the families of 12 victims, told the inquiry that Ismail’s Facebook account had been “viewed and assessed in July 2015, inferentially by MI5.” He had been stopped by police during a “port stop” in September 2015.

Counsel to the inquiry Paul Greaney said that while most of MI5’s evidence would be heard behind closed doors, the inquiry would investigate if Abedi’s family members had a radicalizing influence on Salman and his younger brother Hashem, 23, who helped in the attack and was jailed for murder for at least 55 years.

Cooper said families were urging the inquiry to “rigorously question” MI5 over its decisions regarding Salman and the Abedi family, citing the authorities’ knowledge that Salman had “significant contact” with suspected terrorist recruiter Abdalraouf Abdallah.

Sir John Saunders, the inquiry’s chairman, said that “centrally important material” pertinent to questions over whether MI5 was in a position to stop the attack could not be made public.

“I will ensure that the least possible amount of evidence is heard in private. Claims for the need for national security will be robustly tested,” he told the inquiry.

“Insofar as is possible, and to the extent that is possible without damaging national security, where I identify failings or things that could have been done better in closed hearings, I will make them public as part of my report,” he added.

Ismail, the eldest of the Abedi siblings, has not appeared before the inquiry on the grounds of legal privilege, saying that he could incriminate himself. Earlier this month in a Sky News interview, he apologized for his family and the “pain Hashem and Salman caused.”