Depending on how the St. George library is set up, i.e. if they have a wireless network, he might well have taken his laptop there to use the library's internet. Our library here is set up that way and there are often a dozen people in the room with their own laptops or iPods.
That's true of the Washington County Library System as well.
But if he did, those communications would have shown on his laptop --and anything of a "hidden" nature would have been noticed.