A Sussex man stabbed his elderly mother to death with a kitchen knife before gassing himself in her car in remote woodland.
Terence Hamblen, 50, knifed his mother Joan, 77, repeatedly and attacked her with a claw hammer at the home they shared.
An inquest in Eastbourne heard how after the killing, Mr Hamblen telephoned his aunt, Patricia Orton, in Canada, saying she had died of a heart attack.
He then drove his mother's red Nissan Micra to a bridleway in Studdens Lane, Cowbeech, near Hailsham, and attached a pipe to the exhaust on August 3 last year.
Police did not find the body of Mrs Hamblen, a retired bank employee, until they called to break the news of her son's death. She was found in the kitchen beneath a white bedsheet.
Post-mortem examinations revealed she died from multiple stab wounds while her son died from carbon monoxide poisoning.
Detective Sergeant Gordon Denslow said: "It appears Mr Hamblen killed his mother before killing himself."
Mr Hamblen's father, Stanley, who lived in Tooting, south London, said the pair enjoyed an "excellent" mother-son relationship.
He said there had been no friction in their relationship that could be linked to the killing at their home in Beuzeville Avenue, Hailsham.
He said: "The last time I spoke to Terry he spoke of going to Australia and taking Joan with him. I've never known him to lose his temper in his life."
Although he had received treatment for depression in the past, Mr Hamblen was said to be physically healthy.
His father described him as a loner who had not been married and had no interest in relationships with women.
A computer programmer by profession, he had not worked for about four years but dabbled on the stock market. Through his investments he was said to be financially comfortable and had travelled widely, including to South Africa and Australia.
On the morning of the killing, postman Christopher Maharry heard Mr Hamblen making ferocious noises from the garage and adjoining kitchen.
He said: "I thought he was losing his temper or having an epileptic fit. It sounded like breaking furniture and there was grunting and gasping as if he was making great physical effort.
"I thought about knocking at the door because I was so worried but, as I thought he was having a fit, I decided not to and returned later instead."
On Mr Maharry's return about an hour later, a calm Mr Hamblen answered almost immediately wearing a white polo shirt and navy tracksuit trousers.
He said: "I said, 'Are you alright, because I heard this terrific commotion,' and he said everything was fine.
"I mentioned the noise I'd heard and he said he was moving furniture around in the garage. He was extremely calm and normal."
Toward the end of their five-minute conversation, Mr Hamblen invited Mr Maharry to look around to reassure himself everything was normal.
However, the postman declined and went on his way.
Mr Maharry said: "I never even thought of domestic violence or murder."
Later, passers-by spotted Mr Hamblen slumped in his mother's car in the bridleway in Cowbeech. A bottle of vodka had been used to compress the throttle. No note was found.
Keys found on him were used by police to gain entry to the home, where they found Mrs Hamblen's body in the kitchen.
East Sussex coroner Alan Craze recorded a verdict of unlawful killing on Mrs Hamblen and suicide on Mr Hamblen.
He said: "This is a most rare and very disturbing case and quite rightly the police went into it with a great degree of detail. However, I'm satisfied that the totality of the evidence points in only one direction.
"This case is difficult because a lot of questions are going to be unanswered in that the two witnesses on that Saturday morning are not with us.
"What appears clear is that there was an altercation of some sort and Mr Hamblen flipped and attacked his mother. Having done that he was then seen in and about his home address and the circumstances in which his dead body was later found are clear."
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