A "JEKYLL AND HYDE" dad killed his son with a sledgehammer just days after his wife told him to move out of the family home near Newquay, an inquest heard.
Violent Harold Philpotts, 47, battered son Ben, 10, with the large weapon after telling family members: ''If I can't have my little family then no one can".
Harold, his wife Patricia, 44, and Ben were living with her mum, Betty Bantock, at Trevarrian, when the tragedy happened, the inquest heard.
On January 1, 2010, Patricia told her mum she wanted a divorce but couldn't afford the legal fees – she also told Harold to leave the home.
Seventeen days later on January 18 Betty was in the kitchen with Patricia's niece, Samantha 'Sam' Whitewood, and saw Harold "pacing around" smoking at around 6am.
He suddenly went upstairs and Betty heard a ''terrific explosion" and Harry came down covered in soot and ran out of the house.
Betty ran upstairs to find the home engulfed in fire and emergency crews raced to the home and found "intelligent and happy" Ben lying on his bed.
He had a fractured jaw and skull and extensive bruising to his face and there was blood on his bed sheets and pillow.
The sledgehammer was still lying next to him and he died later in hospital, the inquest heard.
Patricia was also found dead in the home and Harold was found with massive burn injuries and died in hospital nine days later.
Harold was a "Jekyll and Hyde character" who could be "as nice as pie one minute" but ''could change just like that" the inquest heard.
In a statement to the inquest Betty, 82, described the day her daughter and grandson died. She said: ''When I woke up at home I usually wake and go down to have a cup of tea but that morning I thought of taking Ben to school.
"I didn't hear anyone else get up so eventually I did. When I got to the kitchen door I saw Pat who was by the kettle making a cup of tea at a couple of minutes past six.
"Harry was smoking in the conservatory and having a drink. I could see him pacing around but he always did that.
"Once they left the kitchen, a little later I heard a terrific explosion, just like a bomb going off.
"That's when Harry came back down. I heard the explosion first then the shatter of glass.
"I said to Sam (Mrs Philpotts' niece), 'What the hell was that?' and she said, 'I don't know, I thought it came from upstairs'.
"I then saw Harry as he came downstairs. He walked straight past me and out of the door.
"He did not say anything to me and I thought he was going to get a cigarette. I did not see cuts or blood on him at all.
"He walked into the garden and went to the back of the house. I saw him go there, that was the last time I saw him."
Samantha described the relationship between Mr Philpotts and Ben as "very good." She added: "He (Mr Philpotts) always used to say, 'If I can't have my little family then no one can'."
When asked if the incident was an accident she replied: "No, what happened couldn't be an accident.
''The sledgehammer was upstairs. It was usually in the garage, and the door was locked which was unusual.
"He was convinced everyone was trying to kill him, including me."
Harold had mental health issues and had convinced himself he had bowel cancer and the HIV virus, the inquest in Truro, heard. He had also convinced himself his son was ill and sent the bright ten-year-old boy for HIV and cancer tests, it was said.
Betty, of Newquay, said it was "for the best" that Harold had died.
Speaking via a statement Betty said that Harold had been sectioned in 2008 and he began hearing voices who told him he was ill.
She said: "Sometimes he would just go quiet or sometimes he would have an argument. He would go off for weeks without telling anyone.
"She (Patricia) used to tell me how she would return home and find him sitting in the bath crying.
"He spoke of 'these people' telling him what to do and telling him he had cancer and HIV.
"I don't know who these people were; I think they were in his head."
Betty's statement said her daughter planned to file for divorce in the early part of 2010 but couldn't afford to.
Dr Martin Todd, from the Newquay Health Centre, said Mr Philpotts often suffered anxiety of having cancer and HIV and was sectioned in 2008 and 2009.
The inquest continues.