Both crime scenes are still cordoned off and the technical investigations are ongoing, the police write on their website on Saturday.
It was during Friday morning that a woman was murdered in Skultuna and a woman was subjected to an attempted murder in Rönnby in Västerås. The injured woman was taken to hospital with minor injuries.
The women have, or have had, a relationship with the suspected man. All are in their 40s.
The police assessed the perpetrator as dangerous and a VMA was issued in Skultuna during Friday morning. The residents were urged to stay indoors.
The distance between Rönnby and Skultuna, where the crimes took place, is around one mile.
The suspect is detained on probable cause for murder and attempted murder. The police are also investigating several cases of gross child abuse as children were present during the events.
