Detectives are exploring the background of the man whose terror attack in London left four dead after another victim died last night.
Khalid Masood killed a man and a woman when he drove into pedestrians on Westminster Bridge before stabbing PC Keith Palmer to death as he attempted to storm the Houses of Parliament.
Last night a fourth victim - a 75-year-old man - died after his life support machine was switched off.
Masood also died after he was shot by police officers in a bid to prevent him reaching Parliament.
The 52-year-old, with a string of convictions stretching back decades, was unmasked by police as the home-grown terrorist responsible for Wednesday's attack.
Eight people remain in custody following raids across the country since the attack.
Scotland Yard said Masood was born in Kent on Christmas Day in 1964.
Officcers do not believe Masood was his birth name but refused to comment on reports he was born Adrian Elms.
A spokesman said he was known by a number of different names and research into them was continuing.
After leaving Kent, it is thought he most recently spent time in the West Midlands.
On the eve of his attack it is believed Masood spent the night at a hotel in Brighton.
He is also thought to have spend periods living in London, Sussex and Luton.
Scotland Yard said he was not the subject of any current investigations before the massacre and there was 'no prior intelligence about his intent to mount a terrorist attack'.
But he was known to police and MI5 and had convictions for assaults, including GBH, possession of offensive weapons and public order offences
Home Secretary Amber Rudd defended the security and intelligence agencies, saying: "The fact that he was known to them doesn't mean that somebody has 24-hour cover."
She disclosed Masood had spent time in jail, but said it was not for terrorist-related offences.
In a statement, the Islamic State terror group said the attacker was 'a soldier of the Islamic State executing the operation in response to calls to target citizens of coalition nations'.