Detective Chief Inspector Peter Simpson told BBC Scotland's Frontline Scotland that officers had found no evidence that Mrs Fraser, 33, was still alive.

He said: "I am of the opinion that she's dead.

"There's no indication that she's living somewhere else."

The police investigation has been extensive

DCI Simpson spoke to the programme, to be screened on Tuesday, as the investigation into her disappearance prepares to resume with new detectives.

He said: "The only conclusion that's still left open to us, which I firmly believe has happened, is that something criminal has taken place here and that Arlene has been the victim of a crime."

The missing woman's estranged husband Nat said on the programme he thought she was still alive.

He is currently charged with Arlene's attempted murder after allegations related to before her disappearance.

Police have said they are satisfied with his account of his whereabouts on 28 April - the day she vanished from her home in Elgin, Morayshire.

He said: "I still live in hope that someday she'll turn up. I think she's somewhere."

His wife vanished hours after waving her children Natalie, 11, and Jamie, 6, off to school.

Her contact lenses, watches, rings and medicine to treat her Crohn's Disease were left behind in her home and there were no signs of any struggle.

'Sense of loss'

There have been no reported sightings and no money has been withdrawn from her bank account.

Her family now believes they will never see her alive again.

Her sister Carol Gillies told the programme: "I feel a sense of loss. I feel Arlene is dead.

"I feel something has happened to Arlene that is beyond Arlene's control. Arlene wouldn't put us through all this."

The inquiry has cost £250,000 and included interviews with more than 1,000 people.

Detective Inspector Allan Smith said: "We will not let this drop and if things are no clearer in a few month's time then we will look at other avenues of approach."