A 43-year-old Metropolitan Police Specialist Protection officer found dead in a house in north London died from a gunshot wound to the chest, according to a post-mortem.
His death is not being treated as suspicious at this stage.
An inquest will be opened on Monday.
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Nearly 38,000 runners will hope to complete Sunday's London Marathon making it the biggest event in its 35-year history.
Rain across central Britain with longer, intense downpours with thunder in places this evening. A lucky few will stay sunny and dry.
Planning on going to the London Marathon tomorrow? Read our handy guide first!