The wife of a prominent Norwegian businessman is missing in a suspected kidnapping, and her suspected captors have demanded a ransom for her return, police said Wednesday.

Anne-Elisabeth Hagen, 68, the wife of multimillionaire Tom Hagen, disappeared on the morning of October 31, according to authorities.

“We can confirm that there is a ransom, and that serious threats have been issued,” Øystein Stavdal Paulsen, senior adviser of Norway’s East Police District, told CNN.

“Regarding the ransom, we do not want to confirm what amount or in what form,” Paulsen added.

At a press conference Wednesday, Tommy Broeske, assistant chief of police, told reporters that police had been working on the case for “several weeks” but had previously asked media not to report on Hagen’s disappearance as it could possibly endanger her life.

Broeske said that local police were working with Europol and Interpol on the case.

Norwegian state broadcaster NRK reported that multiple messages were found inside the Hagens’ home. The suspected kidnappers have demanded payment in the cryptocurrency Monero, according to NRK.

Police are advising the family not to pay the ransom, Reuters reported.

The Norwegian financial magazine Kapital ranks Tom Hagen, a real estate investor and power facilities owner, at 172 on the magazine’s 400 richest people list. His estimated net worth is around 1.7 billion Norwegian krone (about $200 million), according to Kapital.

Anne-Elisabeth Hagen was a board member of her husband’s holding company until September, according to NRK.

The couple live in Fjellhamar, a village about 20 kilometers (12.5 miles) northeast of Oslo, according to NRK. The couple married in 1979, and have three adult children, it said.