British-born Khalid Masood named as the assailant, had been arrested earlier for violent crimes

Khalid Masood, a lone, British-born attacker, who was known to police and had a string of convictions, was named as responsible for the attack on Westminster on Wednesday. The attack left four persons, including the alleged assailant dead, and around 40 others injured.

Details of the 52-year-old attacker, who had been known by a number of aliases, emerged on Thursday, as reports suggested that the Islamic State (IS) had claimed responsibility, describing the assailant, who was shot dead just within the parliamentary security cordon, as one of its soldiers.

‘No prior intelligence’

Masood was known for a range of offences dating back as early as 1983, when he was convicted for criminal damage, the Metropolitan Police said on Thursday. “Masood was not the subject of any current investigation, and there was no prior intelligence about his intent to mount a terrorist attack.”

Earlier in the day, Prime Minister Theresa May described Masood as a “peripheral figure,” who had been investigated several years ago in connection to concerns about violent extremism. “The case is historic. He was not part of the current intelligence picture… There was no prior intelligence of his intent, or of the plot,” she said.

Masood was born in the county of Kent, south-east of London, but had most recently lived in the West Midlands, a U.K. region which includes the city of Birmingham. The claim of responsibility from the IS was made via Amaq, the group’s news agency, according to Associated Press.