it's making sure that those women understand that the botsvynyuk brothers are in charge. it's keeping every one of those workers in constant fear so that they stay there working every day. >> bergman: four of the five botsvynyuk brothers were charged and convicted. omelyan, the ringleader and rapist, received a life sentence. and oksana? she escaped with the help of a target employee whom she would later marry. >> we think slavery doesn't exist, or if it does exist, it's in some far-off land. slavery is alive and well worldwide, and it is in the united states as well. >> bergman: dave rogers is the head of the human trafficking initiative of the fbi's civil rights unit. i don't see people being led around in chains. >> and that's one of the misconceptions. i can coerce you psychologically, i can coerce you emotionally, i can coerce you financially. >> bergman: how big is this problem? >> we don't know. i'm going to be honest with you, we have no idea the prevalence. but the fbi has more and more cases every year. >> bergman: there are not many studies on the abuse of jani