It was in August 2019 that an 18-year-old woman was shot to death in her apartment in the Stockholm area Råcksta.
The perpetrators had fired automatic weapons into her apartment and were actually meant to meet her husband.
A gang-related conflict was the cause of the shooting.
The police were able to arrest two suspects who were then acquitted in the district court.
The decision was then changed by the Court of Appeal to 16 and twelve years' imprisonment respectively for aiding and abetting murder and aiding and abetting attempted murder.
The man who was arrested in Trosa on Monday was sentenced to twelve years in prison.
Must have had a girlfriend in Trosa
The 30-year-old man has been on the run since the verdict and has been chased by the police.
He was arrested on Monday by police from the East region and the task force from Stockholm.
According to the police's information to Expressen, the man is said to have had a girlfriend in Trosa.
The man must have been handed over to the Swedish Prison and Probation Service to start serving his sentence.