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
Theresa May is considering options to secure statutory powers for child sex abuse inquiry but it may require 'disbanding' current panel.
London mayor Boris Johnson is backing Olympics supremo Seb Coe as his replacement.
A top Fifa official who assessed rival bids to stage the 2018 and 2022 World Cups revealed England’s was by far the strongest contender.