The alarm that a woman had suffered a suspected cardiac arrest came to SOS shortly after 11 on Sunday. Medical personnel on site contacted the police.
The circumstances surrounding the death are unclear and the police cannot therefore rule out foul play.
A preliminary investigation into murder has been opened. The man was arrested at the scene on suspicion of murder, Otto Eriksson told Mariestads-Tidningen.
Relatives have been notified, according to local media.
