Muir was yesterday cleared of the more serious charge of murder but convicted of manslaughter by jurors at Newcastle Crown Court.
Members of grandmother-of-four Pamela’s family gasped and started crying when the jury foreman returned the not guilty verdict on the murder charge.
After battering 55-year-old Pamela to death, Muir taped her up in a duvet and took her 120 miles from home and buried her in a shallow, moorland grave.
The killer dumped a bunch of flowers in a carrier bag on her body, filled in the hole then left messages on his own phone confessing what he had done.
But cunning Muir then went to great lengths to try to cover his tracks, even having the nerve to go back to Pamela’s home and lying to her concerned son that she had gone away after Botox injections went wrong.
Muir, who had denied having anything to do with the killing, showed no emotion as the verdicts were delivered at Newcastle Crown Court yesterday.
Despite evading the life sentence that would have followed for a murder conviction, Muir is still likely to receive a lengthy spell behind bars for manslaughter due to the fact he concealed the body. The killer will be sentenced on Monday.
Pamela’s family had packed into the public gallery hoping for a murder conviction and were left in tears when the foreman said “not guilty” to the charge.
The close-knit family, who have attended throughout the four-week trial, hugged and consoled each other outside court.
Pamela met Muir through a dating website and he left his partner of 32 years for her.
She went missing from her home in Chester-le-Street, County Durham, on March 2 and her body was finally found on moorland above Halifax on May 27.
However, even before they found her body, police were building a strong case against Muir and had him in custody. After attacking Pamela at her home on The Crescent, Chester-le-Street, Muir drove her body to the West Yorkshire moors, which he knew every inch of from cycling and running.
Despite the overwhelming evidence against him, Muir began trying to cover his tracks.
However, Pamela’s blood was found in his car, his fingerprint was in the grave, his phone also placed him at the grave site on the night she was buried and his voicemail recordings confessed to a violent incident.