“What I can confirm is that the man was British-born and that some years ago he was once investigated by MI5 in relation to concerns about violent extremism,” she told MPs on Thursday, a day after an attack outside the UK Parliament in London which left at least four people dead and 40 others injured.
“He was a peripheral figure,” she added. “The case is historic, he was not part of the current intelligence picture.”
She added that “when operational considerations allow, he will be publicly identified.”
In a defiant speech to the Parliament, May said, “We are not afraid and our resolve will never waver in the face of terrorism.”
Lawmakers earlier held a minute’s silence in honor of the victims.
The assailant plowed a car on Wednesday into pedestrians and stabbed a police officer, an incident that has been declared a terrorist incident.