The bodies, believed to be Shelley Saxton-Cooper, 45 and Simon Saxton-Cooper, 50, were found after emergency services were called to a house in Riddings, Derbyshire.
Post-mortem examinations found Shelley died as a result of stab wounds and Simon died from smoke inhalation.
The cause of the fire is not yet known.
Police launched a murder inquiry after the couple were found dead in the partly-collapsed building on Sunday.
The blaze destroyed much of the building's roof and fire crews had to wait several hours for the remaining structure to be declared safe before they could recover the victims' remains.
On Monday, Ch Supt Sunita Gamblin said: "We believe that Shelley was wounded before the explosion and fire. We are treating her death as murder.
Police and fire services are conducting an ongoing investigation and a report is being compiled for the coroner.
It is not believed anyone else was involved, Derbyshire police said.
A pet dog which escaped the blast is being looked after by relatives of the couple.
A woman whose body was found after an explosion destroyed a house died of stab wounds, police have said.