"What I can affirm is that the person was British-born and that some years in the past he was as soon as investigated by MI5 in relation to considerations about violent extremism," she informed lawmakers.
"He was a peripheral determine," she added."The case is historic, he was not half of the present intelligence image."
She stated there had been no prior intelligence of his intent nor of the plot.
"When operational issues permit, he might be publicly recognized," she added.
Police have arrested eight individuals within the investigation into the lone attacker who killed three individuals together with a policeman and injured 40 earlier than being shot lifeless as he tried to enter parliament.
Andrew Parker, director basic of the MI5 home intelligence service, earlier stated his company's operational response had been absolutely mobilised in help of the police.
"We stand shoulder-to-shoulder with our police colleagues, grieving at their loss whereas additionally applauding the skilled excellence of their response," he stated in a press release.