The 22 year old was taken into custody on probable suspicion of murder, the lowest degree of suspicion.
It later emerged that the man has a history of violence. According to Aftonbladet he stabbed his mother to death in November 2000 and served two and a half years’ youth detention.
The 21 year old woman was found early on Tuesday morning, apparently wrapped in a rug.
“We were alerted at about 7.30am by a person who had gone into the flat,” said Ulf Palm, press officer at Västmanland police, to TT.
Police said that the woman was last seen on Sunday afternoon. All indications were that she had been murdered, said Ulf Palm, but he declined to say how she had been killed.
The body will undergo a post mortem on Wednesday and police will then make an official confirmation of the identity.
According to Ulf Palm, no witnesses have yet come forward saying that there was a row in the property.