The man believed to be responsible for yesterday's terrorist attack at Westminster in London has been named as 52-year-old Khalid Masood, who had a range of previous convictions.
While he was born in Kent, detectives believe he had been living most recently in the West Midlands.
Police said he had been "known by a number of aliases".
In a statement, the Metropolitan Police said there was "no prior intelligence about his intent to mount a terrorist attack".
Massod "was not the subject of any current investigations".
Nevertheless, "he was known to police and has a range of previous convictions for assaults, including GBH, possession of offensive weapons and public order offences".
The statement added: "His first conviction was in November 1983 for criminal damage and his last conviction was in December 2003 for possession of a knife.
"He has not been convicted for any terrorism offences."
Earlier, Theresa May said the attacker was a "peripheral" figure who had once been investigated by MI5 over concerns about violent extremism.
In Birmingham, searches are continuing at a flat raided by armed police.
Neighbours said heavily-armed officers had stormed a second-floor flat in Hagley Road overnight.
Three people were killed in the attack before the assailant was shot dead. 29 people were treated in hospital, while seven are said to be in critical condition.
Those killed are: policeman Keith Palmer, a member of the Parliamentary and Diplomatic Protection Squad; a 43-year-old woman, Aysha Frade, who was on her way to pick up her two daughters; and American Kurt Cochran, who was visiting London from his native Utah with his wife Melissa.
Flowers on Westminster Bridge. Image: Kieran Cuddihy
Tributes to victims
US President Donald Trump this afternoon expressed condolences to Mr Cochran's family & friends.
A great American, Kurt Cochran, was killed in the London terror attack. My prayers and condolences are with his family and friends.
— Donald J. Trump (@realDonaldTrump) March 23, 2017
Tributes have also been paid to "wonderful" mother-of-two and "loved" teacher Aysha Frade.
Mrs Frade, a language teacher, was born in Britain and had lived in London her entire life, but her mother was born in Betanzos, near the Galician city of La Coruna in north Spain, and her father was of Cypriot origin.
The family is well known in La Coruna city as her two sisters run a large English language academy in Bentanzos.
Mrs Frade worked in the administration team at DLD College London, just a few hundred metres from Westminster Bridge.
Paying tribute, principal Rachel Borland said she was "a highly regarded and loved member of staff" who would be "deeply missed" by everyone at the college.
Keith Palmer, the unarmed policeman who was stabbed to death as he stood guard outside Parliament, has been described by Theresa May as "every inch a hero" whose "actions will never be forgotten".
Conservative MP James Cleverly, who served with Mr Palmer in the Royal Artillery, described the officer as "a lovely man".
One Irish person was among those injured. Foreign Affairs Minister Charlie Flanagan says his department has, through the Irish embassy in London, offered and stands ready to provide consular assistance.
Islamic State has claimed it was behind the Westminster attack in a statement issued by its Amaq news agency.
In a tweet, the agency said: "A soldier for the Islamic State carried out the operation in answer to calls to target the people of coalition states."
The phrasing suggests the attacker was inspired by Islamic State, and had not been directly trained by it.
