When Nat Fraser received a life sentence for killing his wife in 2003 it seemed justice had been done.

But what followed was a legal row that went all the way to the highest court in the land, with costs estimated to have reached several millions of pounds – all because of three gold rings.

In January 2003, the Crown focused its entire case on the engagement ring, wedding ring and eternity ring, claiming that Fraser must have removed them from Arlene's dead body and placed them in the bathroom of her home nine days after she disappeared.

Prosecutor Alan Turnbull, now Judge Lord Turnbull, said they were the "cornerstone" of the case and claimed that Fraser had placed them there in a bid to show Arlene had run off, leaving him and their two children.

But those rings soon became the grounds of a lengthy appeal process that saw his conviction quashed by the Supreme Court in May last year when new evidence came to light.

The Crown was forced to ask for a retrial after it emerged two police officers claimed to have seen the rings just hours after Arlene's disappearance, and on Monday, April 23, 2012, Fraser returned to the dock for a second trial.

This time round, prosecutors had to reveal mixed accounts of when the rings surfaced – that of Arlene's stepmother who said they appeared days after her disappearance and the two police officers who said they noticed them straight away.

Legal expert Professor Peter Duff, of Aberdeen University, said: "The main argument of the prosecution in the original trial was that the rings only reappeared later and could only have been put there by someone who had access to the body.

"But in this trial, they had to say there's some evidence that the rings were not there at first and there's also some evidence that they were.

"The Supreme Court ruled that they were not absolutely certain that the result would have been the same had this evidence been available at the time of the trial and therefore quashed the conviction."

The new evidence was only uncovered when Fraser's legal team found statements from then Grampian Police Constable Neil Lynch, 59, now transport manager with the London Olympics.

In a report on the case, which was presented to the appeal court, Lord Turnbull said he would have fainted if he had known two police officers could challenge the theory that the rings went missing with Arlene then mysteriously re-appeared nine days later and the trial would had to have fallen.

However, yesterday's verdict suggests that the outcome would have been the same if all evidence had been heard in 2003.

Fraser, who was described as "possessive and controlling", instigated the murder of his estranged wife – and the disposal of her body – after she began divorce proceedings.

The trial heard a claim Fraser told former friend Hector Dick he paid a hitman £15,000 to kill her and said the body had been burned and her teeth ground up.

Arlene disappeared after seeing her children – Jamie, then 10, and five-year-old Natalie – off to school on April 28, 1998.

She was due to see her solicitor that day about a divorce, prompted by an assault the previous month in which Fraser had gripped her by the neck.

She never made that appointment and the disappearance was soon noticed by friends and her son, who left a poignant note at the house, asking: "Where are U?"

The search quickly became a high-profile hunt and her family, who all travelled to Elgin, were struck by Fraser's agitated demeanour and inappropriate jokes.

He also told her father the children would "soon forget their mother", when nobody else knew she was dead.

Fraser, 53, insisted Arlene had run off with money stashed in the house but her loved ones knew she was a devoted mother who would never abandon her children.

They soon suspected her fruit and vegetable wholesaler husband, who had a history of aggression towards her.

Fraser was worried about a costly divorce and, in a chilling prophecy weeks before she vanished, told her: "If you are not going to live with me, you will not be living with anyone."

Mr Dick, who gave evidence for seven days during the trial, said Fraser told him: "If I can't have her, nobody will."

Fraser also spoke of 10,000 people a year who "go missing and never get found".