Three members of the same family died following a bungalow fire, believed to have been started by the father who had a history of mental illness, a court has heard.
Ten-year-old Ben Philpotts was thought to have been bludgeoned with a sledgehammer as he lay in his bed around 6am on January 18, 2010. His mother, Patricia Philpotts, died almost instantly in a blaze which was believed to have been started in her bedroom around the same time Ben was attacked, while Harold Philpotts fled from the property.
Ben was pronounced dead that morning, while Mr Philpotts died in hospital eight days later, suffering from multiple organ failure.
A police investigation subsequently suggested that 47-year-old Mr Philpotts had been responsible for the deaths of his young son and estranged wife, at the property in Trevarrian, Newquay, Cornwall.
Harold and Patricia originally met in Winchester as teenagers and after they began dating had stayed together ever since.
At an inquest into their deaths today, a statement was read from Mrs Philpotts' mother, Betty Bantock, in which she described her son-in-law as a ''Jekyll and Hyde character'', who had a history of hypochondria including being convinced he had HIV and cancer.
On one occasion, he demanded doctors also test his son for HIV, having been convinced - wrongly - the pair were infected.
The hearing in Truro was told Mr Philpotts, also known as Harry, was a regular visitor to the bungalow at weekends, and was unhappy about the prospect of having to return to his flat on the morning of the incident - his 47th birthday.
Mrs Bantock told police: ''I can only assume that Pat had a few words with Harry to go back to his flat. He never wanted to go back.''
She said she woke up around 6am on the day of the fire, sharing a cigarette with her daughter - a data entry clerk at Royal Cornwall Hospital, Treliske - in their conservatory, before Mrs Philpotts went upstairs to her room.
Earlier, Mr Philpotts had been seen ''pacing up and down'' the conservatory while also having a cigarette. He returned inside the main part of the property when the others went out to smoke, she said.
''I then heard a terrific explosion,'' she said in a statement.
''It was like a bomb going off, and then shattering of glass.
''That's when Harry came back downstairs.''
Mrs Bantock's granddaughter - Mrs Philpott's niece, who also lived, downstairs, in the property - said she heard screams from upstairs, as Mr Philpotts walked down the stairs towards the kitchen.
Mrs Bantock, 80, said: ''He walked straight past me.
''I was still stood in the kitchen and I turned my head to look at him.
''He didn't say anything to me.
''I thought he was going for a cigarette.
''I didn't see any burns.''
Emergency services were called but could not save 44-year-old Mrs Philpotts or her son.
The court heard there were two petrol cans found in Mrs Philpotts' room where the fire is believed to have started, while a sledgehammer weighing 7.4kg was found in Ben's bed.
Forensic experts said traces of petrol were found on Mr Philpotts' clothing, after he was arrested nearby, which were typical of a spillage caused when pouring fuel.
Mrs Philpotts' niece, Samantha Whitewood, who was in the bungalow at the time of the fire, recalled the moment she saw Mr Philpotts emerge from the upstairs flat covered in soot and blood.
She said: ''I very quickly became aware of a big smashing sound. I could hear Pat screaming something like 'No!'.
''I walked into the hallway and asked what was going on. I saw Harry coming down. He walked towards the kitchen and was covered in soot.
''He had the most terrified look on his face and an injury to his right arm.
''I said 'What's happened?' He didn't speak, he just walked by.''
She said she ran upstairs, only to be confronted by a layer of ''thick smoke, lying like a blanket''.
Miss Whitewood also told the court that her uncle was unhappy about the prospect of being separated from his wife and son following a breakdown in his relationship with Mrs Philpotts, previously saying: ''If I can't have my little family, no-one can.''
Asked by Cornwall Coroner Dr Emma Carlyon if the three deaths could have been an accident, Miss Whitewood said: ''No. Ben and Patricia were just so happy.''
Forensic pathologist Dr Russell Delaney told the court Mrs Philpotts was ''alive and breathing'' at the time the fire started. She died as a result of extensive burning and charring, while her son was killed by a combination of the effects of a severe blow or blows to the head and from breathing in smoke from the blaze.
Former painter and decorator Mr Philpotts was arrested by police nearby, around three hours after the blaze started, and taken to hospital in Treliske. However, he was subsequently transferred to Frenchay Hospital in Bristol where he was treated for 40% burns. He died, eight days later, following multiple organ failure.
The court heard Mr and Mrs Philpotts, who had begun dating as teenagers in the Winchester area, moved to Cornwall when Mrs Bantock and her husband set up home in the county a decade earlier.
However, Mrs Philpotts and her son left the home they shared with Mr Philpotts in Redruth to move in with Mrs Bantock in Trevarrian when she became widowed.
The court heard Mr Philpotts began to get ill in 2007, and was sectioned the following year. He also suffered from severe bouts of depression, the court heard.
Mrs Philpotts later also experienced stress as a result of her husband's mental health problems. Mrs Bantock told police he would not take his medication because he thought the doctors were trying to kill him.
The inquest was adjourned until tomorrow and is expected to last for three days.