One of London Bridge attackers appeared in TV documentary titled 'The Jihadis Next Door'

One of the London Bridge attackers has been featured in a TV documentary titled "The Jihadis Next Door," where he was seen praying with a black Islamist flag with other British jihadis.

Khuram Shazad Butt, a married father of two, has been filmed unfurling an ISIS flag in the documentary that was aired on Britain's Channel 4.

The 27-year-old jihadi was shot and killed by police after he and two others carried out an attack on London Bridge on Saturday night, leaving seven people dead and 48 injured.

According to Daily Mail, Butt had been known to both the police and MI5, as he has been reported to the police twice, but he still managed to launch the attack on Britain's streets. The police stated that "there was no intelligence to suggest that this attack was being planned and the investigation had been prioritised accordingly."

Reports also emerged that he had made abusive statements in the wake of the murder of British Army soldier Lee Rigby, who was killed outside barracks in Woolwich with knives in 2013.

Butt reportedly threatened a leading Muslim figure for condemning the brigadier's murderers, Michael Adebolajo and Michael Adebowale.

The Independent noted that Butt had been described as a "family man" by his neighbors who did not know that he had appeared in the Channel 4 documentary.

The police identified Butt's accomplice as 30-year-old Rachid Redouane, who was not known to the authorities. Butt had worked at KFC and Transport for London, while Redouane was employed as a pastry chef.

"Work is ongoing to understand more about them, their connections and whether they were assisted or supported by anyone else," the Metropolitan Police stated.

Redouane, who also used the name Rachid Elkhdar, was reportedly married to a Scottish woman, whom he met in Manchester in 2009. However, their relationship reportedly broke down because of his extremist views, and his wife has recently complained that he had not been visiting his daughter enough.

He reportedly visited his daughter in his wife's apartment in Barking to kiss her goodbye just three hours before he carried out the deadly attack.

The authorities have yet to identify their third accomplice, but 12 others have been arrested in connection with the attacks.

The Daily Mail reported that Redouane's estranged wife was one of 12 arrested, but she was released without charge.

"The investigation into this horrific attack is fast-moving and complex as we piece together a fuller picture of what occurred," the Metropolitan Police said.