Police said a note found in the couple's house, east of Oslo, described what would happen to her if the demanded ransom wasn't paid in the cryptocurrency Monero.
Police did not give a figure for the ransom amount, but Norway's VG newspaper reported it was 9 million euros (USD 10.3 million.) The newspaper reported that the note said Falkevik Hagen would be killed if police were involved.
Broeske declined to comment other than saying "the threats (in the note) were of a very serious character."
"The reason for us to go public with this case now is that despite a broad and extensive investigation, we need more information," he told a news conference.
"We have no suspects in this case," he said. Police have been "on the case for several weeks. That is all I'd say," he added.
Broeske said "those behind have chosen to communicate digitally and we have had no other type of contact." Police had urged the family not to pay any ransom.
Police believe she disappeared from the couple's home, some 50 kilometres from the Swedish border.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)