In total 160 court and police files were studied from four different European countries (Romania, The Netherlands, Bulgaria, England), representing areas usually associated with origin, transit and destination of human trafficking. In the 160 files we found information on 233 traffickers. In addition, we interviewed or received information by way of questionnaires from 101 traffickers. Lastly, we consulted a range of professional experts, victims of human trafficking, lawyers and social workers. The total number of conducted and studied questionnaires is 50.