A Commons committee has heard that Mohammed Ahmed Mohamed, who escaped from a mosque in West London, was involved in fighting, attack planning and recruiting for Al Shabab in Somalia.
The Home Affairs Committee is hearing evidence from David Anderson, the independent reviewer of terror laws. Anderson says Terrorism Prevention and Investigation Measures are not a foolproof way of keeping the population safe, adding:
"I'm troubled by the fact that there are cases which can't be prosecuted at all."
More top news
Around 60 firefighters tackled the blaze at the four-storey building in Daleham Gardens, Hampstead, that broke out early on Tuesday.
It is the fourth time in five years that the London borough has topped the rankings, according to data from the ONS.
Catherine Burke's body was discovered at a house in a quiet street in Muswell Hill last Thursday evening.