The man was arrested after police were called to the Kvarngärdet area of the city. It appears that the 50 year old himself had asked passers-by to call the police, after telling them that his partner was dead.
When police arrived they found the man in the stairwell with blood on his trousers and his three year old daughter in his arms.
In the apartment was the 27 year old woman. According to the local paper Upsala Nya Tidning, she was still alive.
“She had been exposed to terrible violence,” said Christer Nordström at Uppsala police, to TT.
The woman died shortly after police arrived. The girl was taken into care by the social services.
“The man has said that the child was in the apartment during the incident itself, but we still don’t know what the child witnessed,” said Nordström.
A knife was found in the apartment which police believe could be the murder weapon.
The man, who was not previously known to police, is being held on suspicion of murder.
“He denies the charge, but has made a number of admissions. He confessed, for example, that the family was alone in the flat at the time,” said Christer Nordström.
No motive has been established.
On Monday police will continue their forensic examination of the apartment, and a post mortem will be carried out.