The report was produced by the Swedish Agency for Health Technology Assessment and Assessment of Social Services on behalf of the Government.

Focused deterrence means focusing society's resources on a smaller group of people who are responsible for a large part of the gang violence. An example of where this is already happening is the "Stop Shooting" project in Malmö.

"You offer them support to leave this type of behavior, but you also make it clear what will happen if they don't and that you will do everything you can to make their criminal activities more difficult. It has proven to be effective in reducing gang shootings and drug crime," says Amir Rostami, professor of criminology.

The second point, school-based initiatives, should be aimed at all pupils, primarily in middle school. This may involve skills training in, for example, conflict resolution, which can prevent young people from starting to carry weapons, the report states.

The third point, psychosocial interventions, is aimed at gang criminals in probation. This may include CBT therapy, support in seeking employment and substance abuse treatment. According to the report, such efforts can almost halve continued criminality up to a year after the end of the intervention.

Needs to be adapted to Sweden

18,000 studies from different countries have been reviewed to find the measures that work best to prevent young people's gang crime. They have since been narrowed down to some 20 studies with the highest empirical support.

Most of the studies that have been used come from the United States.

"There are always adaptation problems, but we still believe that these models are preferable because they have proven to be effective in other countries. It's better that we adapt these models than that we come up with our own that are not evidence-based," says Amir Rostami.