I am not sure there is serious research done. Probably not. There is no interest as it is a career ending move. Some news: http://www.bbc.com/news/world-europe

I am not sure there is serious research done. Probably not. There is no interest as it is a career ending move. Some news: http://www.bbc.com/news/world-europe-37161752 http://www.bbc.com/news/world-europe-37161752 http://www.thelocal.se/20160404/teen-stabbed-in-street-flown-to-hospital-in-stockholm http://www.thelocal.se/20160404/teen-stabbed-in-street-flown... http://sverigesradio.se/sida/artikel.aspx?programid=2054&artikel=5891564 http://sverigesradio.se/sida/artikel.aspx?programid=2054&art... https://www.nrk.no/kultur/nrk-team-truet-og-kastet-stein-etter-i-sverige-1.12934238 https://www.nrk.no/kultur/nrk-team-truet-og-kastet-stein-ett... (Norwegian - a Norweigan tv-crew is attaced in a suburb.) https://en.wikipedia.org/wiki/No-go_area#Sweden https://en.wikipedia.org/wiki/No-go_area#Sweden (Claims 55 areas, the referenced source lists around 100 additional areas that are on the police's "watch list" whatever that means.) https://sv.wikipedia.org/wiki/S%C3%B6dert%C3%A4ljen%C3%A4tverket https://sv.wikipedia.org/wiki/S%C3%B6dert%C3%A4ljen%C3%A4tve... (swedish - Assyrian mafia in Södertälje) http://www.huffingtonpost.com/magnus-norell/the-muslim-brotherhood-in_1_b_10880432.html http://www.huffingtonpost.com/magnus-norell/the-muslim-broth... (Not really related to the crime, but also problematic due to the segregation that follows a muslim society within the society.)