"The British man shot dead in the Texas synagogue siege was investigated by MI5 in late 2020, Whitehall sources confirmed to The Times."

"Malik Faisal Akram, 44, was the subject of a 'short lead investigation' for at least four weeks.... The authorities were already facing questions about why Akram was able to travel to the US, where he purchased a handgun, given he had a criminal record for offences including violence... Akram, from Blackburn, who once ranted about the September 11 attacks, was part of MI5’s pool of 40,000 closed subjects of interest.... The case was closed before it progressed to a full-blown inquiry involving intrusive techniques such as eavesdropping.... When he travelled to the US in late December, Akram was not on the Home Office warnings index, the watchlist that allows police at airports to intercept would-be passengers of concern. Sources said that it would be 'disproportionate' for someone assessed as being no threat to be on the list."

The London Times reports.

I'm sure you've read elsewhere that the rabbi engineered the escape — which involved throwing a chair at the armed hostage-taker. I like this justifiably proud statement by the rabbi, Jeffrey Cohen: "We escaped. We weren’t released or freed." 

"The Texas Department of Public Safety said the man had demanded to see his 'sister,' who may not actually be related to him and who is currently in U.S. federal custody..."

"... for 'terroristic events' in Afghanistan. 'The man claims he and his sister will be going to Jannah (Muslim belief of heaven) after he sees her,' the department said in a statement earlier on Saturday. The congregation had been holding a service... being live streamed on its Facebook page when... a man could be heard shouting about dying and not liking police officers... Many Jews expressed exhaustion on Saturday at the security concerns surrounding practicing their faith at a time when antisemitism comes from many sources, including white supremacists and Islamic extremists.... 'This is Jewish life in 2022... If you attend religious services without armed guards at the entrance and without fear of attack... you do not experience religious life as American Jews do.'"

From "Hostages Rescued Safely, Suspect Dies in Texas Synagogue Standoff" (NYT).