Four people, including a police officer, died when Khalid Masood drove a rented car into crowds on Westminster Bridge and then stabbed the unarmed police officer before being shot dead.
According to the Metropolitan Police, Masood has previously gone by the names of Adrian Elms and Adrian Russell Ajao. He may also be known by a number of other names.
Acting Deputy Commissioner Mark Rowley appealed for the public’s help.
He said, “We named the dead terrorist as Khalid Masood, and as I said, our investigation focuses on understanding his motivation, preparation and his associates.
“Whilst there is no evidence of further threats you will understand our determination to find out if he either acted totally alone inspired by terrorist propaganda or if others have encouraged, supported or directed him.
“At this point I want to appeal specifically to the public.
“We remain keen to hear from anyone who knew Khalid Masood well, understands who his associates were, and can provide us with information about places he has recently visited.
“There might well be people out there who did have concerns about Masood but weren’t sure or didn’t feel comfortable for whatever reason in passing information to us.
“I urge anyone with such information to contact us the Anti-Terrorist hotline which is 0800 789 321.”
Detectives are continuing to search a number of addresses linked to the investigation, and a total of 11 people have been arrested as part of this.
A 39-year-old woman was arrested at an address in east London on suspicion of preparation of terrorist acts.
She has since been released on bail until a date in late March. A 21-year-old woman and a 23-year-old man were arrested at an address in Birmingham.
A 26-year-old woman and three men aged 28, 27 and 26 years old, were arrested at a separate address in Birmingham.
The six still in custody were arrested on suspicion of preparation of terrorist acts. A 58-year-old man was also arrested on the morning of Thursday at a separate address in Birmingham on suspicion of preparation of terrorist acts.
A 27-year-old man was arrested late on Thursday, 23 March at an address in Birmingham and a 35-year-old man was arrested in the early hours of this morning at an address in Manchester.
A 32-year-old woman was also arrested this morning at a location in Manchester.
All three were arrested on suspicion of preparation of terrorist acts Ten people remain in police custody.