He motivates the request by stating that the evidence situation makes it "unnatural" if the Crown Princess does not want to answer the police's questions, which could shed new light on the case.
The Oslo police have not yet returned with whether they intend to call in Mette-Marit for questioning.
In August, Marius Borg Høiby was arrested, suspected of assaulting a woman he had a relationship with. He later admitted in a statement to NRK that he had used violence against his girlfriend and stated that he had used alcohol and cocaine at the time.
Two more women have come forward with allegations that Marius Borg Høiby was violent when they were together with him. He is also suspected of unlawful threats in several cases, according to Norwegian police.
Mette-Marit is currently on sick leave due to side effects from the medication she takes for the chronic lung disease pulmonary fibrosis.
