vice lieutenant mary petri is not surprised. >> it is not atypical.here are many of these commercial establishments that you have hiding places, hidden stairwells, mirrors that open. we find that frequently. it's an indicator of potential trafficking victims who are being hidden so it's up to us to determine whether this person is in the situation where they need assistance. we give every woman a card, referral card that's in her language so she knows where she can seek help if she feels she can't come to us for help that the moment. >> officers say unfortunately if a girl is clearly in trouble or working under threat she will rarely leave with them. as frustrating as it is, the task force says they'll continue their efforts because the buying and selling of humans shows no sign of abating. >> with painful stories like minh's many mind, san francisco's human trafficking task force keeps the pressure on the criminals who make a profit out of sexual enslavement. their goal, make it tougher to enslave vulnerable girls and women like minh who are unwillin