A twisted killer murdered his wife and hid her body underneath the floorboards of their home, just metres away from where his millionaire mistress slept in the garden shed.
In the new series of Netflix's Meet Marry Murder, one episode tells the horrific story of Harry Jarvis and how he murdered his wife, Carol Jarvis at their home in Bathgate, West Lothian, Scotland.
Bizarrely, Jarvis' infatuated mistress, Jus-Rol pastry heiress Rita Heyster, had been living in the garden shed at the time of the murder in September 2009.
She helped him to conceal Carol's body, which was then left to decay under the floorboards, GrimsbyLive reports.
Jarvis' son Graham explains in the episode how the couple made the decision to move from London, where they met, to the Scottish town a few miles from Edinburgh after Harry had "fallen out" with his family.
In 2000, a degenerative muscle condition saw Carol, then 38, become wheelchair-bound, after which Jarvis became her full-time carer. But before long, he began having affairs with other women and met Rita Heyster.
After squandering her £2.5m fortune, Heyster "needed a roof over her head" and Jarvis fitted out the garden shed with a mattress for her to live in, while Carol was bedbound just four feet away inside the house.
"Everyone knew she was living in the garden shed. It must have been the strangest circumstances for local gossips to talk about," barrister Tony Kent says in the documentary.
Graham Jarvis explains how his dad, Harry, was responsible for administering the medication for his sickly mother and would give her so many sleeping tablets that she would sleep throughout the day.
He said: "When dad had maybe went away on one of his vanishing episodes and we gave mum her medication, she seemed to perk up a lot more, wake up, and go back to getting up out of bed. Alarm bells started ringing, but as young adults, how do you question your dad, in terms of that she was fine one minute and then not the next?".
Twisted Jarvis and Heyster hatched a plan to poison and murder Carol - who had become an "inconvenience" - to allow them to be together.
In a sick letter to Heyster, Jarvis wrote: "Drugs are doing job just took longer than I thought. But going fast now. See you in paradise soon. Carol is dying as I write. Then we have house to ourselves and sell all in it to move on."
When Carol's children visited the house and questioned Jarvis about her whereabouts, he bizarrely told them she was visiting Dundee because the couple were planning on moving there.
"That was the time that alarm bells started ringing that something wasn't right," Graham said.
The siblings contacted police, who visited the property and found Heyster hiding under a bed. Unbelievably, her and Jarvis told officers that she was in fact Carol. But one officer had previously met Carol and knew they were lying.
Jarvis then told police that Carol was in Dundee and that he would travel the following day to collect her. Officers proceeded to search the house and soon discovered Carol's body underneath the floorboards.a
Because of the state of decomposition the body was in, investigators were unable to determine her cause of death.
The twisted couple had gone on the run, and police launched a manhunt to find them. They were arrested by police as they exited a bus in Edinburgh and taken to the police station to be interviewed.
Jarvis told police that Carol had died after suffering a fit during sex with him after she asked him to strangle her, and that he had placed her body underneath the floorboards because he "couldn't bear" to be without her. He pleaded not guilty to her murder, but the jury at the subsequent trial found him guilty.
Jarvis was jailed for life in 2011 for the murder of Carol. He was ordered to serve a minimum of 15 years before being eligible for parole. Heyster was locked up for four-and-a-half years for helping to conceal Carol's body.
Graham said: "I don't think I'll ever forgive him for what he's done."
Jarvis died in prison of heart failure aged 67 in 2017.
Heyster was jailed for four years after being convicted of attempting to defeat the ends of justice by helping her boyfriend to cover up the crime.
