Despite extensive police inquiries, no cause of death has been established in the case of Rina Yasutake, whose remains were found at the home she shared with her mother and siblings in Helmsley, North Yorkshire.

Suspicions were raised at a local chemist in September 2018, when her brother Takahiro, 51, and sister Yoshika, 56, repeatedly bought bottles of surgical spirit over a period of days.

The emergency services were called to the address in Bondgate, where paramedics found her dead body under a duvet on a mattress on the floor.

It was obvious the 49-year-old had been dead for weeks, the inquest into her death was told.

But the reclusive family continued to believe she was alive.

Craig Hassall KC, representing the family, asked Detective Inspector Nichola Holden, who led the police investigation, if the family was "utterly convinced" that she was alive when the emergency services attended.

The detective replied: "They were at the time and for many months after."

Home Office pathologist Dr Jennifer Bolton said it was hard to determine how long Ms Yasutake had been dead, given the extent of mummification, but that the level to which it had developed took "some weeks".

Ms Yasutake's brother, sister, and 80-year-old mother Michiko Yasutake were charged with preventing a lawful and decent burial, but the prosecution was halted when it was found the family, originally from Japan, suffered from a rare mental disorder.

Coroner Jon Heath was told there was no evidence of any third-party involvement in her death, no sign of injury or toxicological cause.

Rina Yasutake was a talented pupil and won a scholarship to Cambridge University where she studied classics, specialising in linguistics.

She didn't work after university and the family had lived together in Helmsley for 20 years, the inquest was told.

In statements given to a psychiatrist, the brother and sister said that during the course of 2018, Rina Yasutake stopped eating, grew weaker and began to move less and less.

Earlier that year, it was recorded that Ms Yasutake, who was 4ft 11in tall, weighed just six stone six pounds.

Her sister Yoshika Yasutake told the psychiatrist: "She didn't say much so we said to her to eat and drink more.

"She looked like she was being nourished by eating her soul.

"I don't know how to explain.

"Even though she was not eating, she was nourished with spiritual food and she was fulfilled."

Mr Hassall described his clients as "very insular and isolated" and Ms Holden agreed that even when using a Japanese interpreter, communication was difficult, as the family spoke their own dialect.

Ms Holden added that during inquiries, it was found they had no means of communicating with the outside world and had no TV or radio.

Mr Heath recorded an open conclusion, saying: "I am unable from the evidence available to determine how she died."

The family did not attend the inquest, but Mr Heath said they will listen to a recording of it later.