The bodies, believed to be Shelley Saxton-Cooper, 45, and Simon Saxton-Cooper, 50, were found after emergency services were called to a house on Valley View Road on Sunday.
A Home Office pathologist carried out post-mortem examinations on their bodies and determined that Mrs Saxton-Cooper died as a result of stab wounds and Mr Saxton-Cooper died from smoke inhalation.
A Derbyshire Constabulary spokesman said: “The cause of the fire is not yet known and the police and fire service are conducting an ongoing investigation.
“A report is being compiled for the coroner who will hold an inquest into the deaths at a future date.”
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On Tuesday, police announced they are treating the incident as suspicious and Mrs Saxton-Cooper’s death as murder.
The spokesman added: “We don’t believe, at this time, that anyone else is involved.”