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
Will the 'potentially historic' snow storm hitting the US, find its way to the UK?
19-year-old Angus Mainland took a selfie with his mystery traveler at the weekend. He fell in love. But forgot to ask for her number.
A study says ingredients in some common drugs could increase the risk of dementia. Alzheimer's Research UK say more research is needed.