Malik Faisal Akram is seen in this handout photo taken at a faith based daytime outreach center in Dallas, Texas, US, January 2, 2022 and obtained by Reuters on January 18, 2022. Courtesy of OurCalling, LLC./Handout via REUTERS

The terrorist who took four hostages at a synagogue this past Saturday raised no security flags upon entering the US, the White House said Tuesday, despite revelations that he was previously investigated by British intelligence in 2020.

The British intelligence service MI5 considered Malik Faisal Akram, who was a UK citizen, a Subject of Interest (SOI) and investigated him in late 2020, the BBC and other UK media outlets reported. By 2021, however, he had been dropped as an SOI.

Akram flew to the US at the end of December in order to commit the attack, in which he held four people hostage at Congregation Beth Israel synagogue for over 10 hours. After one hostage was freed unharmed during the standoff, the remaining three escaped safely, while Akram was killed.

White House press secretary Jen Psaki said during a briefing Tuesday that US authorities had found no reason to deny Akram entry.

“Our understanding, and obviously we’re still looking into this, is that he was checked against US government databases multiple times prior to entering the country, and the US government did not have any derogatory information about the individual in our systems at the time of entry,” she said.

“We’re certainly looking back, as I referenced, at what occurred to learn every possible lesson we can to prevent attacks like this in the future,” Psaki continued.

Akram, who also had a criminal record in the UK, had undergone a four-week investigation that found no cause to place him on a higher priority list, the BBC reported.

MI5 investigates, on average, around 600 SOIs at any given time, and has information on 40,000 former SOIs. Investigations are undertaken only if the agency considers a subject an active threat.

On Tuesday, the Greater Manchester Police announced that its Counter Terrorism Policing North West unit had released without charges two teenagers detained in Manchester on Sunday in connection to the attack.

“CTP North West is continuing to assist with the investigation which is being led by US authorities,” said Temporary Assistant Chief Constable Dominic Sally. “Overnight, constructive meetings with colleagues from the United States have taken place.”

Manchester police also said that an address in North Manchester had been searched as part of the investigation. They did not reveal any details about the identities of the two teenagers held.

Akram, originally from the Blackburn area of Lancashire, north of Manchester, said he took the hostages to obtain the release of Aafia Siddiqui, who is imprisoned in nearby Fort Worth, Texas for a 2010 conviction for shooting at US soldiers and FBI agents in Afghanistan.