The international policy currently adopted to combat the growing phenomenon of trafficking in human beings (THB) is victim centred. The policy intends to fully address this phenomenon, focusing on victim protection as well as preventing and criminalising such conduct. In Spain, efforts are underway to achieve internationally established standards. However, the research we present here shows how much work remains to be done, particularly in trafficking cases that are less well known, such as trafficking for exploiting victims in criminal activities. Our research aimed to better understand the processes of trafficking for criminal exploitation and to determine whether the criminal justice system is prepared to detect and protect victims of such processes. The qualitative study we developed investigates cases of 45 migrant women held in two Spanish prisons and evidences that there are individuals victimised in the highest degree. At least ten respondents had been victims of trafficking, and not only were they not identified as such by legal authorities, they were also imprisoned for a crime that their traffickers forced them to commit.