A husband is thought to have strangled his wife then hanged himself, police said.
Ambulance crews fought in vain to save the woman, aged in her 60s, and the body of the man, also in his 60s, was found elsewhere in the flat.
The drama happened on Wednesday at a property in Rugby Street, Bloomsbury, central London, Scotland Yard said.
A Yard spokesman said it was a murder investigation but at this early stage officers were not looking for anyone else in connection with the deaths.
Post-mortem examinations took place yesterday at St Pancras Mortuary and gave the causes of death as strangulation for the woman and injuries consistent with hanging for the man.
More top news
A band of wet and rather windy weather will move east across the British Isles, giving some heavy bursts of rain in the north.
Motoring experts have raised concerns over the Government's clean air strategy to ban new diesel and petrol cars and vans from 2040.
"Touch base", "blue sky thinking" and "we're on a journey" were revealed as the most annoying office jargon, according a study by Glassdoor.