Police say that it has been virtually impossible to identify individual rioters due to the large number of people involved and because many wore balaclavas. There is also a lack of witnesses, police say.
There were 400 police reports in total during the riots, which lasted for around 10 days.
One person received a prison sentence after torching two cars. Two others received fines, one for using drugs and the other for carrying a teargas canister. Another person, accused of crimes against Sweden's knife laws, is awaiting trial and several cases of violent rioting are still under investigation.
The disturbances broke out on May 19th in the Stockholm suburb of Husby where youths set fire to cars and threw stones at police. The riots then spread to other Stockholm suburbs. At least 150 cars and several buildings were torched, with insurance companies estimating the cost of damages to around 60million SEK.
Researcher: Police whitewashed Husby results
Stefan Holgersson, a police officer who also researches criminal justice issues at Linköping University, says the police have given a whitewashed version of their efforts to control the riots.