The man was previously unconvicted and resident in Västra Götaland.
The police were alerted to a shooting in the Hageby district shortly after midnight on June 3 last year. In an apartment, two men in their 30s were found shot dead.
The murders are connected to a conflict between criminal networks in Norrköping.
The 20-year-old was not acquainted with the victims beforehand and is not believed to have had any connection to Norrköping previously.
Two other young men were charged with aiding and abetting the killings, but were acquitted by the Norrköping district court.
