The obvious digital detective work: issuing subpoenas to PayPal, Facebook, MySpace and Yahoo to get identifying information and IP addresses for the person who had posted fake profiles, placed ads, and posted videos online.
The complainant sought IP address and other contact details for the poster of the fake profile but again FB-I pointed out that such information could only be provided by legitimate legal means such as a court order or via a relevant law enforcement authority relying upon a relevant legal basis.