The man was shot dead in a car outside Björklinge, north of Uppsala , Arbetarbladet has reported. The woman and her son were in the car at the time.
On Monday a 39-year-old man who was suspected of killing the woman, who comes from northern Uppland, was arrested. He and the woman were acquaintances. According to the preliminary post mortem the 51-year-old woman died from knife wounds.
The suspect has neither admitted nor denied the attack, say Gävle police. He claims not to remember anything from Thursday afternoon until lunchtime on Friday.
Legal proceedings against the man must begin by August 6th.