A 19-year old man has been arrested at Heathrow airport on suspicion of "preparing for acts of terrorism" in relation to Syria, police said.
The man is being held at a police station in London and an address in the north of the city is being searched, the Metropolitan police said in a statement.
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The 20-year-old was found fatally wounded on Roth Walk, near Finsbury Park, north London at around 3am on Saturday, Scotland Yard said.
Daniel Cowell has been jailed for five years and four months after ramming a police patrol car with a stolen transit van.