>> He was on the police radar, then fell off it.>> We're looking at his history.>> Details emerging of Khalid Masood, the British born assailant who plowed a car through crowds on Westminster Bridge on Wednesday. And stabbed an officer before police shot him dead. He was born Adrian Russell, he's from Kent.
And Reuters' correspondent Bill Schomberg says a profile of the man is coming together.>> Well, he's 52 years old, which is relatively old for the typical kind of profile of people who've been carrying out this kind of attacks in the UK and elsewhere. We believe that he was a convert to Islam at some stage in his life.
Police are currently trying to go through all his computer records, phone records, trying to work out who his associates were.>> Masood's name appears in a UK counter-terrorism investigation from five years ago. He'd racked up a string of non terror related convictions. His last 14 years ago for possession of a knife.
Masood wasn't under investigation at the time of the attack but he'd shown up on the periphery of such probes in the past. Islamic states claiming him as one of their soldiers, but police still aren't sure whether he acted alone.>> Well Islamic State did claim that they were behind the attack.
But when they made their message a couple of days ago, they didn't actually name the individual, and his name since came out. So some doubt as to whether there really is a connection there. Police said a couple of months ago that they're working on that assumption, that it was Islamist inspired.
>> Most police raids have focused on Birmingham, where Masood lived for at least some years>> Two significant arrests there made overnight. US government sources telling Reuters the attacker knew people who travel to join Jihadi groups abroad, but had never done so himself. This budget hotel in Brighton, where Masood is believed to have spent his last night before heading to London.
The exact motive for what's happened next, still far from clear.