The former cabaret singer apparently took the secrets of this "perfect murder" to her grave - but today the Daily Mail can reveal the chilling story in full.
Despite the couple masquerading as the "epitome of middle-class respectability", the killing was the culmination of a turbulent 37-year marriage, a string of fraud allegations, abandoning their five children, and a menage-a-trois with a violent criminal half their age.
Now it has emerged that Sabine, 75, confessed days after the murder in 1997 during a phone call to one of her few friends, Valerie Chalkley.
She assumed Sabine was joking and it was only after John's remains were discovered outside her flat in Beddau, near Pontypridd, South Wales, a few weeks after she died that her friend realised she must have been telling the truth.
John Sabine's remains were discovered a few weeks after his wife died. Photo / Supplied
Mrs Chalkley told the Mail: "It was a couple of years since we'd spoken, so I said 'I wondered what had happened to you both. I would have thought by now that one of you would have killed the other.'
"She replied, 'It's funny you should say that. I've killed him. I've battered him with a stone frog which was at the side of the bed. He was just driving me mad. Every night he would get into bed crying and weeping, saying you don't fancy me.'"
Sabine is believed to have wrapped the body in a car cover and stuffed it under her bed. She is thought to have moved the remains to the communal rubbish area at her block of flats when she knew she was dying, telling a neighbour the package contained a medical skeleton from her days as a trainee nurse.
After marrying in 1960, the Sabines emigrated to New Zealand and had five children, but abandoned them in a care home when police were about to pounce over a series of frauds.
Leigh-Ann during her cabaret career. Photo / Supplied
Mrs Chalkley first met Sabine in 1988 when she had returned with John to Britain. She said: "They looked a lovely couple, the epitome of respectable."
But Sabine confided that she found the senior Vodafone accountant's constant attention controlling. When Sabine finally left him, she asked Mrs Chalkley to drive her to a hotel in Bournemouth, which turned out to be full of recently released convicts.
Sabine, then in her 50s, began an affair with a hardened criminal half her age after she hid him from police in her room as he clutched a bloodied machete. The man, known only as Steve, had chopped off the fingers of another criminal who had failed to give him his agreed spoils from a robbery.
Sabine and her new lover moved into a flat in Bournemouth. "She stayed with him even after he savagely beat her up," Mrs Chalkley said. "I think she liked the criminal lifestyle. It gave her a buzz."
John was devastated and hired a private detective to follow Mrs Chalkley when she was visiting Sabine.
Jane Sabine, Leigh Ann and John's daughter, whom they abandoned in New Zealand 47 years ago. Photo / Nick Reed
He then moved into Sabine's one-bedroom flat in Bournemouth - sharing it with her new lover. Mrs Chalkley said: "It was a very odd set up." The Sabines then moved to Wales without Steve in 1995.
Mrs Chalkley didn't hear from Sabine until two years later - when she made the "confession."
Whenever she asked about John, Sabine always replied: "He's just the same."
Mr Chalkley said: "I no longer had any concerns, and over the years it became a joke in my family and if someone did something wrong we'd say, 'Watch out or I'll frog you.'"
She contacted police after reading about the discovery of John's body in the Mail. Her evidence is expected to be part of John's inquest which resumes next week.
Mrs Chalkley said: "If anybody put themselves in a position to be murdered it was him. He would rather have been dead than without her and that, very sadly, is what happened."
