THE search for Pamela Jackson’s body, and the hunt for her killer, was one of the biggest investigations ever undertaken by Durham Police.

In the first days after the 55-year-old was reported missing by her son Joe, the search centred on the area round her Chester-le-Street home.

But, after an analysis of Muir’s mobile phone records, Operation Sorrento shifted its attention to Soyland Moor, near Halifax, in West Yorkshire, where the suspect had earned his living as a drystone waller and grouse beater.

Detective Superintendent Ken Donnelly said: "Muir went to incredible lengths to dispose of the body. He is a drystone waller who knew how to lay foundations and dig quickly.

"He was an experienced fell runner and although not a big man, was fit and strong. And he also knew the area like the back of his hand.

"He had all the skills to dig the grave and construct a series of layers of soil, clay and other material.

"A previous employer described Adrian as a ‘perfectionist’ at work and that is in keeping with all he did to cover his tracks, dispose of evidence and remove Pamela’s body more than 120 miles away."

Through number plate recognition systems, CCTV footage and the trace of his mobile phone signal, detectives were able to prove Muir had visited the moors in the days before Pamela was reported missing.

Up to 40 officers from Durham and West Yorkshire endured difficult search conditions each day as they scoured the 2.6-mile length of the B6138 Turvin Road, near Ripponden for signs of the missing woman.

The teams searched ground up to 150 metres either side of the road, fringed with thick grass, bogs, pools of water and heather, while Turvin Road was closed for a week under several feet of snow.

Sergeant Rachel Stockdale, who led the search teams on the ground, said: "It was a huge and challenging task which saw the teams work some very long hours. Much of it was in extreme weather, usually thick fog, heavy rain and high winds."

She added: "The sole aim was to locate Pamela and bring her back home for her family."

Only when the weather lifted, did police get their crucial breakthrough which would lead to Muir’s conviction.

Det Supt Donnelly said: "He went to great lengths to ensure the remains stayed hidden and in fact we had already searched that area three times before the weather improved.

"Small cracks in the ground then started to open up which meant the sniffer dogs could get a scent.

"Without that breakthrough it is very possible the body might still be missing."

Throughout his trial, Muir vehemently denied killing his girlfriend and insisted he was being framed by the real killer.

He told the court Pamela had thrown him out of the house during a row about her use of Botox and that she was alive and well when he last saw her.

But during the lengthy trial, police and prosecution built up an overwhelming case against him and his strenuous claims of innocence were systematically dismantled by the weight of forensic evidence.

Muir’s fingerprint was found on a Tesco carrier bag wrapped around some flowers and buried with Pamela in her shallow moorland grave.

Soil found inside Muir’s Kia car was analysed and found to come from West Yorkshire, experts identifying the most likely source as a site within 700-metres of the spot where her body was eventually found.

Fibres found on duct tape in the grave were proven to match fibres found in Muir’s car and a throw discovered in his home, a throw which police believe was used to cover her battered body as he drove to the moors.

Detectives also discovered a rambling message recorded on his own phone in which Muir said he could not continue to live and that there had been a "disaster".

Det Supt Donnelly said: "At no stage did he ever have the decency to admit his guilt and confess what he had done.

"He did all in his power to frustrate the investigation and it took a huge amount of resources, plus sheer graft and dedication to bring him to justice."