It is understood the investigation was "mid-level" and took place in the second half of 2020 – but once it had ended Akram was left as a closed subject of interest on MI5's records, and no information of concern appears to have been passed to the US authorities before the synagogue attack.

The Security Service's investigation lasted "over four weeks", a source said.

Akram, a 44-year-old from Blackburn, was killed after an 11-hour hostage standoff at the Congregation Beth Israel synagogue in the Dallas suburb of Colleyville on Saturday evening.

All four hostages were unharmed.

Two teenagers arrested in Manchester after a British gunman took hostages at a Texas synagogue have been released without charge.

Police also searched an address in north Manchester as part of their investigation.

it is not yet clear how akram had a criminal record in the uk, was able to travel to america.

Family say he was 'suffering from mental health issues' Akram's family has said he was "suffering from mental health issues".

It has emerged Akram was previously investigated by MI5 and had ranted about the 9 terror attacks during a 2001 court appearance in Blackburn.

Akram travelled to the US around the time of the new year, and spent time in homeless shelters in Dallas.

"He ’ s known to police.

"we were terrified," his brother gulbar said in a statement.

Malik Faisal Akram, 44, arrived in the US at Kennedy Airport in New York on 29 December and was questioned by customs officials, but as there were no red flags in the system he was allowed to enter the country, according to NBC.

Akram, who took four people including a rabbi hostage, had told family members he wanted to get married and was going to go to Texas to find a Mexican bride.

It is believed he purchased a gun on the streets which had been stolen in 2020.

Akram demanded release of al Qaeda suspect During the standoff with police in Colleyville, Akram demanded the release of Aafia Siddiqui, a Pakistani neuroscientist who is suspected of having ties to al Qaeda and was convicted of trying to kill US troops in Afghanistan.

One hostage was freed after around six hours, and three others including the synagogue's rabbi managed to flee before the FBI stormed the building and shot Akram dead.

Two teenagers arrested in Manchester by officers from Counter Terror Policing North West as part of the investigation into the attack have since been released.

"Overnight, constructive meetings with colleagues from the United States have taken place.

he has described how he escaped.

He told CBS : "The last hour or so of the standoff, he wasn't getting what he wanted… it didn ’ t look good.

"when i saw an opportunity where he wasn't in a good position, i made sure that the two gentlemen who were still with me ... were ready to go.

"The exit wasn't too far away.

i told them to go, i threw a chair at the gunman, and i headed for the door," he said.

"And all three of us were able to get out without even a shot being fired."

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