Suspect, Khairi Saadallah, 25, had been investigated last year but no serious risk was identified, sources say

The suspect in an alleged terror attack that left a teacher and two others dead was known to security services and other authorities, it emerged on Sunday.

Khairi Saadallah, the 25-year-old Libyan refugee held over the stabbings in a Reading park, was on the radar of MI5 in the middle of last year, sources told the Guardian.