Deputy Assistant Commissioner Martin Hewitt, of the Metropolitan Police, says there remains "gaps in understanding" regarding the death of MI6 worker Gareth Williams.
But he has concluded, following two years of investigation, that it is "most probable" that the codebreaker was alone at the time of his death.
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The film appears to show the executions of Ethiopian Christians on the beach in Libya. It has not been verified.
Hundreds of Newcastle fans are taking part in a protest in the city centre ahead of today's home game against Tottenham.
Man City tightened their grasp on fourth spot with a comfortable 2-0 victory over West Ham at the Etihad Stadium