Kidnappers are demanding a ransom after taking the wife of one of Norway’s richest men hostage.
Police have revealed that Anne-Elisabeth Falkevik Hagen, married to billionaire property investor Tom Hagen, has not been seen since 31 October.
There have been no signs of life from the 68-year-old, police say, but no indication she is dead either.
A note was found demanding the ransom is paid in cryptocurrency Monero and explaining what would happen if the money is not delivered.
Police have not said how much the ransom is, but Norwegian newspaper VG said it was €9m (£8m).
The paper also claimed the note said she would be killed if police became involved.
Mr Hagen, who is also the majority owner of Elcraft, an electricity company, is number 172 in the country’s rich list and is thought to be worth 1.7bn kroner (£1.57bn).
Chief investigator Tommy Broeske said the threats in the note were “of a very serious character”.
He said: “The reason for us to go public with this case now is that despite a broad and extensive investigation, we need more information.
“We have no suspects in this case.
“Our main theory is that the victim was kidnapped by unidentified perpetrators at her home.”
He said officers had been working on the case for several weeks and have urged the family not to pay the ransom.
Mr Broeske said those behind the kidnap have chosen to communicate digitally and officers have had no other form of contact.
Police are working with Interpol and Europol on the case.