"We will continue the investigation and will give more information as soon as possible," prosecutor Tove Kullberg said in a statement on Friday.
Swedish police revealed earlier this week that it suspected five persons with alleged ties to extreme-left organizations for playing part in the altercation in Kärrtorp, southern Stockholm, in December. All five are suspected of rioting, with the man born 1988 who was detained in absentia on Friday facing an additional attempted manslaughter probe.
Seven alleged neo-Nazis have already faced rioting, with some charged with hate speech, at Södertörn District Court. The suspected ring leader claimed in court that he and his cohorts had been attacked, rather than the other way around.
Residents of the southern suburb had rallied to protest against the sprouting of Nazi graffiti when members of the Swedish Resistance Movement showed up. The scene quickly descended into violence with several people suffering knife wounds.
The following weekend, Stockholmers gathered in their thousands to protest the violence.