prostitution placed by pimps. >> using coy code words like roses or diamonds, these ads show men just what they're buying. >> this is the craigslist operation. >> with help from a federal human trafficking grant, the oakland pd along with the fbi conduct internet sting operations. >> oakland police. open the door so we don't have to use the key. >> on this night, after knerd spotted a pimp with two suspected minors, they enter a hotel room and find a pregnant 17-year-old selling herself and the minors on the internet. >> you're logging on. >> during questioning, the pregnant teen admits to posting internet ads for her pimp while the other minors walked the track for cash. >> were they supposed to work tonight? yes, and i was supposed to. >> though she's been beaten and hospitalized multiple times, the girl who's been sold online