According to them he did not simply film her once on a lucky chance, he was stalking her across the country and filmed her 8 times, in a number of different hotel trooms and at least two different cities.
Barrett was caught because he tried to sell the tapes to TMZ, the gossip site, and they informed the FBI. How about that eh, a gossip site with a conscience?
There's more on Michael Barrett:
Michael David Barrett was arrested Friday night as he arrived on a flight from Buffalo, N.Y., the FBI said. He faces federal charges of interstate stalking for taking the videos, trying to sell them to celebrity Web site TMZ and posting the videos online, the FBI said in a statement.