Adrian Muir killed 55-year-old grandmother Pamela Jackson by fracturing her skull during a row at her home, then drove her 120 miles to the hills above Halifax, West Yorkshire.
The stonemason had placed a bunch of flowers on her body in the shallow grave he dug on Soyland Moor in late March. The cold late spring hampered police’s efforts to find her, and her resting place was only discovered in May.
By that time 51-year-old Muir, who met Ms Jackson on a dating website, had been charged with her murder.
He continued to deny being the killer at his trial at Newcastle Crown Court, despite overwhelming evidence, and yesterday the jury found him not guilty of murder but guilty of manslaughter.
His phone was tracked making the journey from Chester-le-Street to the West Yorkshire moor on the night she disappeared, and he had parked up close to where he dug the grave, 85m off the B6138 near Ripponden.
Muir, of Calder Terrace, Halifax, told the jury he knew “every inch” of Soyland Moor, having regularly run, biked and worked as a beater on grouse shoots there.
His fingerprint was found on the plastic bag the flowers in the grave were kept in.
In the days after killing Ms Jackson at her home in Chester-le-Street, County Durham, Muir was suicidal and recorded a series of messages on his iPhone, saying he could not continue to live and that there had been a “disaster”.
A CCTV camera at a Chester-le-Street supermarket car park captured him cleaning the back seat of his Kia car with products he had just bought in the shop.
In the witness box, Muir, claimed he had both been set up by the real killer, and was also a victim of coincidence and bad luck.
Ms Jackson, a mother-of-three adult sons who suffered from bi-polar disorder, had a volatile relationship with Muir, and had taunted him in a series of texts, calling him “ugly” and boasting she had a new lover.
The police investigation into Ms Jackson’s disappearance and death was one of the largest Durham Police has ever undertaken.