Police discovered the bodies of psychiatrist Dr Saman Mir Sacharvi (49) and her daughter Vian Mangrio at their fire-damaged semi-detached house in Burnley, Lancashire, on the morning of October 1st last year.
The badly burned body of Miss Mangrio was found in the lounge and her mother covered in soot - with her clothing doused in petrol - in the upstairs bedroom with a fuel container next to her feet and a fuel cap on the bed, Preston Crown Court heard.
Post-mortem examinations revealed the doctor died from pressure to the neck and the schoolgirl died of asphyxia.
The Crown says on the evidence "the finger will point fairly and squarely" at handyman and part-time Tesco supermarket worker Shahbaz Khan (51), as the killer.
David McLachlan QC, opening the prosecution case, said in the previous week the doctor collected her daughter early from school after she reported Covid-19 symptoms.
The clinician, known locally as Dr Saman, emailed colleagues at the NHS on September 28 to inform them they were self-isolating as they awaited Miss Mangrio's coronavirus test result, which later proved negative.
When the police and crime scene investigators entered the address in Colne Road they saw saw writing on the walls, continued the prosecutor.
Mr McLachlan said: "The writing said things such as 'Covid 19 house my mum is evil', 'Covid home' and 'Help me'.
"It is the prosecution case that this was a cynical attempt by Shahbaz Khan to portray the relationship between Dr Saman and her daughter Vian Mangrio as a bitter one in order to steer the blame away from him. An attempt to put the blame onto Vian Mangrio for her mother's death."
Khan had previously carried out repairs at Dr Saman's home including a garage conversion.
He arrived at the address shortly before 11-50am on September 30th where he was expected to continue more building work, the court was told.
Moments later Dr Sacharvi sent an e-mail to a colleague and was expected to join a Microsoft Teams meeting between 1pm and 4pm, but did not attend and the Wi-Fi was no longer active from about 1.50pm.
It is alleged that Khan killed the psychiatrist before Miss Mangro arrived back home from school at 3-25pm and then attacked her daughter.
Both victims' mobile phones were detached from the network later in the afternoon and Khan did not return calls to his phone as he left the house at 10pm, the court heard.
Later recovered from the crime scene were two small bottles of Blossom Hill rose wine and a small bottle of strawberry and banana Innocent smoothie bought by the defendant the day before the killings, said Mr McLachlan.
Mr McLachlan said when news of the deaths emerged in the following days the defendant told a friend he had last seen Dr Saman a few days ago when he put some picture frames up for her and said to someone else he had not been at the house since the extension work.
Khan was arrested on October 4th and police searched his home where they discovered in the loft a bag containing items of gold jewellery, worth tens of thousands of pounds, belonging to Dr Saman.
Khan, of Ribble Avenue, Burnley, denies two counts of murder and one count of arson being reckless as to whether life was endangered.
His wife, Rabia Shahbaz (45), also of Ribble Avenue, denies doing an act intended to pervert the course of public justice, namely providing a false alibi for her husband.
The trial is estimated to last up to four weeks, with the prosecution opening continuing today (Tuesday).