London, UK - A British gunman who took hostages at a Texas synagogue was previously investigated by Britain's MI5 domestic security service.

Malik Faisal Akram was shot dead when the FBI stormed Congregation Beth Israel synagogue in Colleyville on Saturday night.

The 44-year-old, originally from Blackburn, England, was investigated by the security services in 2020 but deemed not to be a credible threat to national security at the time, official sources confirmed to Britain's PA news agency.

It is not yet clear how Akram, who had a criminal record in the UK, was able to travel to the US two weeks ago.

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US officials believe Akram had a visa, arrived at John F Kennedy International Airport in New York and bought the handgun used in the incident.

According to reports, he stayed at a homeless shelter and is believed to have bought a gun on the street before taking four people hostage at the synagogue on Saturday, one of whom was released after around six hours.

At one point he demanded the release of Pakistani neuroscientist Aafia Siddiqui, who was convicted of trying to kill US army officers in Afghanistan, and is in prison in Texas.

President Joe Biden branded the incident "an act of terror" and UK police are working with authorities in America on the investigation.

Akram became a subject of interest (SOI) for MI5 when he was investigated in 2020 but was assessed not to pose a credible threat to national security, so was downgraded and marked a "closed" SOI.

He was not subject to a live investigation when he travelled to the US, PA understands.

MI5 investigates around 3,000 SOIs and has about 600 live investigations at any one time. There are also around 40,000 "closed" SOIs – those who have been looked into previously. Significant numbers of SOIs are overseas.

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Home Secretary Priti Patel said she had spoken to her US counterpart, Alejandro Mayorkas, and offered "the full support" of the UK police and security services in the investigation.

The FBI in Dallas had earlier said there was nothing to suggest a wider terror plot.

Akram's family said they were "absolutely devastated" by what had happened and "do not condone any of his actions," according to a statement that was shared on the Blackburn Muslim Community Facebook page.

The statement was attributed to Akram's brother, Gulbar. He said he had been involved in negotiating from the UK with his sibling during the ordeal, and added that the hostage-taker "was suffering from mental health issues."