Can't believe some of you are sitting around just sending out notices. They're stealing from you, they don't care. Play hardball.
Lot of the girls on the site look real young. They obviously don't have IDs. Make life interesting since they're in the U.S.
https://tips.fbi.gov/
http://www.ic3.gov/complaint/default.aspx
And if you know where they are located.
http://www.fbi.gov/contact/fo/fo.htm
Nothing wrong with reporting a potential crime taking place online. There is no harm in them investigating whether the girls are 18 and over or not.