The woman is being held on reasonable suspicion, the lower level of suspicion, according to a press release from the Swedish Prosecution Authority.
On Wednesday morning, two people were reported missing after a boat trip. After a major search effort, the boat carrying the missing people was found on Lake Vättern. The man on board was found lifeless and his life could not be saved.
As the circumstances surrounding the death are unclear, a preliminary investigation into suspected murder has been opened. The woman denies any wrongdoing.
"The investigation is now continuing, including various technical examinations and questioning," says prosecutor Clara Åbyhammar in the press release.
The woman must be remanded in custody or released by 12 noon on Saturday at the latest.
